Method of photocatalytic degradation and water splitting using nanocomposite
12508458 ยท 2025-12-30
Assignee
Inventors
- Mohamed Khairy Abdel Fattah Omran (Riyadh, SA)
- Mohamed Mokhtar Mohamed (Benha, EG)
- Gamal Owes El-Sayed Owes (Benha, EG)
- Enas Ebrahim Abdelmonem Mohamed (Benha, EG)
- Babiker Yagoub Elhadi Abdulkhair (Riyadh, SA)
Cpc classification
A62D2203/04
HUMAN NECESSITIES
International classification
Abstract
A nanocomposite material including iron sulfide (FeS.sub.2) nanoparticles, iron oxide (-Fe.sub.2O.sub.3) nanoparticles, titanium dioxide (TiO.sub.2) nanoparticles, and graphitic carbon nitride (C.sub.3N.sub.4) nanosheets and a method of its preparation. The nanocomposite is used in a method of forming oxygen gas from water using an applied voltage and photoirradiation, a method of forming hydrogen gas from water using an applied voltage and photoirradiation, and a method of photodegrading organic pollutants using visible light photoirradiation.
Claims
1. A nanocomposite, comprising FeS.sub.2 nanoparticles; -Fe.sub.2O.sub.3 nanoparticles; TiO.sub.2 nanoparticles; and C.sub.3N.sub.4 nanosheets, wherein the nanocomposite has a ratio of Fe(II) to Fe(III) of 0.50:1 to 1.15:1; and the nanocomposite has a mean particle size of 100 to 400 nm.
2. The nanocomposite of claim 1, wherein the TiO.sub.2 nanoparticles are present in an amount of 1 to 15 wt. %, based on a total weight of nanocomposite; and the C.sub.3N.sub.4 nanosheets are present in an amount of 1 to 15 wt. %, based on a total weight of nanocomposite.
3. The nanocomposite of claim 1, having a band gap of 1.65 to 2.15 eV; and an electrochemical surface area of 13 to 40 mFcm.sup.2.
4. The nanocomposite of claim 1, having a saturation magnetization of 0.001 to 0.1 emu/g; a remnant magnetization of 0.0001 to 0.01 emu/g; and a coercivity of 500 to 2000 G.
5. A method of forming the nanocomposite of claim 1 the method comprising hydrothermally treating an aqueous mixture of an iron precursor and thiourea at 150 to 250 C. for 2 to 28 hours to form an iron-comprising component; calcining a mixture of imidazole, hydrochloric acid, and titanium dioxide at a first temperature of 300 to 375 C. for 2 hours and a second temperature of greater than 375 to 450 C. for 1 hour to form a titanium-comprising component; and ultrasonically treating a suspension comprising the iron-comprising component, the titanium-comprising component, and an alcohol having 1 to 4 carbon atoms to form a precursor mixture; and drying the precursor mixture to form the nanocomposite.
6. The method of claim 5, wherein the iron precursor is iron (III) acetate; and the aqueous mixture has a ratio of iron (III) acetate to thiourea of 1:1 to 1:5.
7. The method of claim 5, wherein the alcohol having 1 to 4 carbon atoms is methanol; the suspension has a ratio of the iron-comprising component to the titanium-comprising component of 0.01 to 0.15; and the ultrasonically treating is performed for 6 to 24 hours.
8. A method of electrochemically forming oxygen gas by an oxygen evolution reaction, the method comprising: contacting the nanocomposite of claim 1 with an aqueous electrolyte solution comprising 1.0 M KCl; and applying a potential of 0.01 to 1.5 V to the nanocomposite and a counter electrode immersed in the aqueous electrolyte solution, and irradiating the nanocomposite with visible light.
9. The method of claim 8, wherein the nanocomposite has an oxygen evolution reaction onset potential of 0.75 to 1.25 V relative to the reversible hydrogen electrode.
10. The method of claim 8, wherein the nanocomposite has a potential required to generate a current density of 10 mAcm.sup.2 (10) of 0.95 to 1.25 V relative to the reversible hydrogen electrode.
11. The method of claim 8, wherein the nanocomposite has a Tafel slope of 37.5 to 65 mV dec.sup.1.
12. A method of electrochemically forming hydrogen gas by a hydrogen evolution reaction, the method comprising: contacting the nanocomposite of claim 1 with an aqueous electrolyte solution comprising 1.0 M KCl; and applying a potential of 1.2 to 0.01 V to the nanocomposite and a counter electrode immersed in the aqueous electrolyte solution, and irradiating the nanocomposite with visible light.
13. The method of claim 12, wherein the nanocomposite has a hydrogen evolution reaction onset potential of 0.25 to 0.01 V relative to the reversible hydrogen electrode.
14. The method of claim 12, wherein the nanocomposite has a potential required to generate a current density of 10 mAcm.sup.2 (10) of 0.75 to 0.25 V relative to the reversible hydrogen electrode.
15. The method of claim 12, wherein the nanocomposite has a Tafel slope of 40 to 10 mV dec.sup.1.
16. The method of claim 12, wherein the nanocomposite has a turnover frequency of 0.20 to 0.40 s.sup.1.
17. A method of photodegrading an organic pollutant, the method comprising: irradiating with visible light a photodegradation mixture comprising the organic pollutant, an oxidant selected from the group consisting of hydrogen peroxide and a persulfate salt; and the nanocomposite of claim 1, wherein the organic pollutant is at least one selected from the group consisting of a dye, a phenol, a polycyclic aromatic hydrocarbon, an herbicide, a pesticide, an antibiotic, and a persistent organic pollutant.
18. The method of claim 17, wherein the nanocomposite is present in the photodegradation mixture in an amount of 0.01 to 0.75 g/100 mL, based on a total volume of the photodegradation mixture.
19. The method of claim 17, wherein the method degrades 70 to 99% of an initial amount of organic pollutant in a reaction time of 180 minutes.
20. The method of claim 17, wherein the oxidant is potassium persulfate; and the organic pollutant is an antibiotic.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more complete appreciation of this disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
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DETAILED DESCRIPTION
(77) In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words a, an and the like generally carry a meaning of one or more, unless stated otherwise.
(78) Furthermore, the terms approximately, approximate, about, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween.
(79) As used herein, the term hydrothermal treatment or hydrothermally treating refers to a process or method involving the use of high-temperature and high-pressure water vapor to induce chemical reactions or transformations in materials. This process typically occurs in a closed system, allowing for the solubilization, crystallization, or synthesis of various compounds, including nanoparticles, ceramics, and composites. Hydrothermal treating is often employed to enhance the structural, thermal, and mechanical properties of materials, facilitating the development of advanced functional materials for applications in catalysis, energy storage, and environmental remediation.
(80) As used herein, the term electrochemical surface area refers to the effective area of an electrode that participates in electrochemical reactions. It is an important parameter in electrochemistry, as it influences the kinetics of electron transfer and the overall performance of electrochemical systems, such as batteries, fuel cells, and sensors. The electrochemical surface area can be determined using techniques such as cyclic voltammetry or impedance spectroscopy, providing insights into the active sites available for reaction and the efficiency of charge transfer processes at the electrode interface. A higher electrochemical surface area generally correlates with improved reaction rates and enhanced performance of the electrochemical device.
(81) As used herein, the term saturation magnetization refers to the maximum magnetization that a magnetic material can achieve in the presence of an external magnetic field. It represents the extent to which the magnetic moments of the material align in response to the applied field. Saturation magnetization is a critical parameter in characterizing magnetic materials, as it indicates their ability to retain magnetization and influence their performance in applications such as magnetic storage, magnetic resonance imaging (MRI), and magnetic separation processes. This value is typically expressed in units of emu/g (electromagnetic units per gram). It is determined through magnetic measurement techniques such as vibrating sample magnetometry (VSM) or superconducting quantum interference device (SQUID) magnetometry.
(82) As used herein, the term remnant magnetization refers to the magnetization that remains in a magnetic material after an external magnetic field has been removed. This phenomenon occurs when the magnetic moments within the material retain a certain degree of alignment due to magnetic interactions, resulting in a non-zero magnetization in the absence of an applied field. Remnant magnetization is an important characteristic in the study of magnetic materials, as it indicates the material's ability to retain magnetic properties, which is important for applications such as permanent magnets, magnetic recording media, and magnetic memory devices. The level of remnant magnetization is typically measured using techniques like hysteresis loop analysis, and it is represented as a specific value that reflects the material's coercivity and overall magnetic stability.
(83) As used herein, the term coercivity refers to the measure of a magnetic material's resistance to becoming demagnetized. Specifically, it quantifies the intensity of the external magnetic field that must be applied to reduce the magnetization of a material to zero after it has been magnetized. Coercivity is a critical parameter in determining the suitability of a material for various applications, such as permanent magnets and magnetic storage devices. High coercivity indicates that a material can maintain its magnetization despite external magnetic influences, making it ideal for applications requiring strong and stable magnetic properties. Conversely, low coercivity materials are more easily demagnetized and are typically used in applications where temporary magnetization is sufficient. Coercivity is often assessed through hysteresis loop measurements, which illustrate the relationship between magnetization and applied magnetic field.
(84) As used herein, the term oxygen evolution reaction (OER) refers to the electrochemical process in which water or hydroxide ions are oxidized to produce oxygen gas, along with protons and electrons. This reaction typically occurs at the anode during water splitting or in various electrochemical cells, such as fuel cells and electrolyzers. OER is an important reaction in energy conversion and storage technologies, particularly in the context of renewable energy applications, as it is often coupled with hydrogen evolution reactions to harness clean energy from water. The efficiency and kinetics of the OER are significantly influenced by the choice of catalyst materials, as well as the reaction conditions, including pH and temperature. Understanding and optimizing OER is vital for enhancing the overall performance of systems designed for sustainable energy production.
(85) As used herein, the term Tafel slope refers to a quantitative measure of the relationship between the overpotential (the additional voltage required beyond the equilibrium potential) and the current density in an electrochemical reaction, particularly in the context of electrode kinetics. It is derived from the Tafel equation, which describes how the rate of an electrochemical reaction varies with the applied potential. The Tafel slope is typically expressed in millivolts per decade (mV/decade) and provides insight into the reaction mechanism and the efficiency of the catalyst used in processes such as the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). A lower Tafel slope indicates faster reaction kinetics and more efficient electrochemical performance, making it an important parameter in the evaluation of electrocatalysts in energy conversion and storage applications.
(86) As used herein, the term hydrogen evolution reaction (HER) refers to an electrochemical process in which hydrogen gas (H.sub.2) is generated from an aqueous solution, typically involving the reduction of protons (H.sup.+) at the cathode of an electrochemical cell. This reaction is important in various applications, including water splitting, electrolysis, and fuel cells, as it provides a means to produce hydrogen, a clean energy carrier. The efficiency of the HER is influenced by factors such as the choice of catalyst, electrode material, and reaction conditions (e.g., pH and temperature). The kinetics of the HER can be evaluated through parameters such as overpotential and Tafel slope, which are important for optimizing catalysts used in hydrogen production.
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(88) At step 52, the method 50 includes hydrothermally treating an aqueous mixture of an iron precursor and thiourea to form an iron-comprising component.
(89) In some embodiments, the hydrothermally treating is performed at 150 to 250 C., preferably 155 to 245 C., preferably 160 to 240 C., preferably 165 to 235 C., preferably 170 to 230 C., preferably 175 to 225 C., preferably 180 to 220 C., preferably 185 to 215 C., preferably 190 to 210 C., preferably 195 to 205 C., preferably 200 C. In some embodiments, the hydrothermally treating is performed for 2 to 48 hours, preferably 4 to 44 hours, preferably 6 to 42 hours, preferably 8 to 40 hours, preferably 10 to 38 hours, preferably 12 to 36 hours, preferably 14 to 34 hours, preferably 16 to 32 hours, preferably 18 to 30 hours, preferably 20 to 28 hours, preferably 22 to 26 hours, preferably 24 hours.
(90) In general, the iron precursor can be any suitable source of an iron (II) or iron (III) ion. In some embodiments, the iron precursor dissociates into an iron (II) and/or iron (III) ion and an anion in water. Examples of suitable iron precursors include but are not limited to iron (II) sulfate, iron (III) chloride, iron (II) chloride, iron (III) nitrate, ferrous ammonium sulfate, iron (II) sulfide, iron (III) sulfide, iron (III) oxide, iron (II) oxide, iron (II, III) oxide, iron (III) hydroxide, iron (II) fumarate, iron (III) citrate, iron (II) malate, iron (III) bromide, iron (II) oxalate, iron (III) phosphate, iron (II) carbonate, iron (III) sulfamate, iron (II) tartrate, iron (III) thiocyanate, and iron (II) acetate. In a preferred embodiment, the iron precursor is iron (III) acetate.
(91) In some embodiments, the concentration of the iron precursor may range from 0.01 M to 1.0 M, preferably 0.05 to 0.90 M, preferably 0.1 to 0.75 M, preferably 0.15 to 0.5 M, preferably 0.20 to 0.40 M, preferably 0.225 to 0.30 M, preferably 0.25 M.
(92) In some embodiments, the concentration of thiourea may range from 0.1 M to 1.5 M, preferably 0.25 to 1.25 M, preferably 0.5 to 1.0 M, preferably 0.6 to 0.9 M, preferably 0.7 to 0.8 M, preferably 0.75 M.
(93) In some embodiments, the aqueous mixture of iron (III) acetate to thiourea may have a ratio ranging from 1:1 to 1:5, preferably 1:1.5 to 1:4.5, preferably 1:2 to 1:4, preferably 1:2.25 to 1:3.75, preferably 1:2.5 to 1:3.5, preferably 1:2.75 to 1:3.25, preferably 1:2.9 to 1:3.1, preferably 1:3.
(94) In some embodiments, the iron-comprising component may include an iron oxide. Examples of iron oxide include, but are not limited to, Fe.sub.3O.sub.4, Fe.sub.2O.sub.3, FeO, Fe.sub.4O.sub.5, Fe.sub.5O.sub.6, Fe.sub.5O.sub.7, Fe.sub.25O.sub.32, and Fe.sub.13O.sub.19. In some embodiments, the iron-comprising component comprises Fe.sub.2O.sub.3. In general, the Fe.sub.2O.sub.3 can be any suitable phase of Fe.sub.2O.sub.3. Examples of phases of Fe.sub.2O.sub.3 include, but are not limited to -Fe.sub.2O.sub.3 (also referred to as alpha phase or hematite), -Fe.sub.2O.sub.3 (also referred to as beta phase), -Fe.sub.2O.sub.3 (also referred to as gamma phase or maghemite), and -Fe.sub.2O.sub.3 (also referred to as epsilon phase). In some embodiments, the iron-comprising component comprises -Fe.sub.2O.sub.3.
(95) In some embodiments, the iron-comprising component may include an iron sulfide. Examples of iron sulfides include, but are not limited to, FeS, FeS.sub.2, Fe.sub.3S.sub.4, Fe.sub.1-xS, and Fe.sub.2S.sub.3. In some embodiments, the iron-comprising component comprises FeS.sub.2.
(96) In some embodiments, the iron-comprising component may include an iron carbide. Examples of iron carbides include, but are not limited to, Fe.sub.2C and Fe.sub.3C. In some embodiments, the iron-comprising component is substantially free of an iron carbide. In some embodiments, the iron-comprising component can include iron hydroxide (Fe(OH).sub.3). In some embodiments, the iron-comprising component is substantially free of iron hydroxide (Fe(OH).sub.3). In some embodiments, the iron-comprising component comprises both FeS.sub.2 and -Fe.sub.2O.sub.3. In some embodiments, the iron-comprising component is substantially free of iron-containing materials and/or phases other than FeS.sub.2 and -Fe.sub.2O.sub.3.
(97) At step 54, the method 50 includes calcining a mixture of imidazole, hydrochloric acid, and titanium dioxide to form a titanium-comprising component. In some embodiments, the mixture is calcined at a first temperature of 300 to 375 C., preferably 310 to 370 C., preferably 320 to 365 C., preferably 330 to 360 C., preferably 340 to 355 C., preferably 350 C. for a first time period and a second temperature of greater than 375 to 450 C., preferably 380 to 440 C., preferably 385 to 430 C., preferably 390 to 420 C., preferably 395 to 410 C., preferably 400 C. for a second time period. In some embodiments, the first time period (i.e., the duration of the calcination at the first temperature) is 0.5 to 6 hours, preferably 0.75 to 4 hours, preferably 1 to 3 hours, preferably 1.5 to 2.5 hours, preferably 2 hours. In some embodiments, the second time period (i.e., the duration of the calcination at the second temperature) is 0.25 to 3 hours, preferably 0.5 to 2 hours, preferably 0.75 to 1.5 hours, preferably 1 hour. In some embodiments, the calcination may be conducted with a heating rate ranging from 1 to 10 C./min, preferably 2 to 8 C./min, preferably 3 of 6 C./min, preferably 4 of 5.5 C./min, preferably 5 C./min.
(98) In some embodiments, the titanium-comprising component includes an inorganic titanium phase. Examples of inorganic titanium phases which may be included in the titanium-comprising component include, but are not limited to, Ti.sub.3C.sub.2, TiN, TiC, TiO, Ti.sub.3O.sub.5, TiAl.sub.3, TiB.sub.2, TiSi.sub.2, TiH.sub.2, TiZr, TiP, TiS, TiFe, TiC.sub.2, TiO.sub.2-x, TiNb.sub.2O.sub.5, TiOxNy, TiO.sub.2SnO.sub.2, Ti4O.sub.7, and titanium phosphates. In a preferred embodiment, the titanium-comprising component comprises TiO.sub.2. In some embodiments, the titanium-comprising component further comprises a carbon nitride. In general, the carbon nitride can be any suitable carbon nitride. Examples of suitable carbon nitrides include, but are not limited to -C.sub.3N.sub.4 and g-C.sub.3N.sub.4 (also referred to as graphitic carbon nitride). In some embodiments, the titanium-comprising component comprises g-C.sub.3N.sub.4.
(99) At step 56, the method 50 includes ultrasonically treating a suspension comprising the iron-comprising component, the titanium-comprising component, and an alcohol having 1 to 4 carbon atoms to form a precursor mixture.
(100) In general, the alcohol having 1 to 4 carbon atoms may be any suitable alcohol having 1 to 4 carbon atoms. Examples of alcohols having 1 to 4 carbon atoms include, but are not limited to, methanol, ethanol, n-propanol, isopropanol, tert-butanol, 1-butanol, 2-butanol, cyclopropanol, cyclobutanol, glycerol, propylene glycol, butylene glycol, and 1,2-butanediol. In some embodiments, the alcohol having 1 to 4 carbon atoms is methanol.
(101) In some embodiments, the suspension may have a ratio of the iron-comprising component to the titanium-comprising component ranging from 0.01 to 0.15, preferably 0.02 to 0.12, preferably 0.03 to 0.11, preferably 0.04 to 0.10. In some embodiments, the suspension may have a ratio of the iron-comprising component to the titanium-comprising component of 0.04. In some embodiments, the suspension may have a ratio of the iron-comprising component to the titanium-comprising component of 0.10.
(102) In some embodiments, the ultrasonic treatment may be performed for 2 to 24 hours, preferably 4 to 20 hours, preferably 6 to 18 hours, preferably 8 to 16 hours, preferably 10 to 14 hours, preferably about 12 hours.
(103) At step 58, the method 50 includes drying the precursor mixture to form the nanocomposite. In some embodiments, drying may be performed at 25 to 100 C., preferably 40 to 75 C., preferably 50 to 70 C., preferably 55 to 65 C., preferably 60 C. In some embodiments, the drying is performed overnight in an oven.
(104) In some embodiments, the nanocomposite has a ratio of Fe(II) to Fe(III) of from 0.50:1 to 1.15:1, preferably 0.60:1 to 1.10:1, preferably 0.75:1 to 1.05:1, preferably 0.80:1 to 1:1, preferably 0.85:1 to 0.95:1.
(105) In some embodiments, the nanocomposite comprises FeS.sub.2 nanoparticles. In general, the FeS.sub.2 nanoparticles can be any shape known to one of ordinary skill in the art. Examples of suitable shapes the FeS.sub.2 nanoparticles may take include spheres, spheroids, lentoids, ovoids, solid polyhedra such as tetrahedra, cubes, octahedra, icosahedra, dodecahedra, hollow polyhedra (also known as nanocages), stellated polyhedra (both regular and irregular, also known as nanostars), triangular prisms (also known as nanotriangles), hollow spherical shells (also known as nanoshells), tubes (also known as nanotubes), nanosheets, nanoplatelets, nanodisks, rods (also known as nanorods), and mixtures thereof. In the case of nanorods, the rod shape may be defined by a ratio of a rod length to a rod width, the ratio being known as the aspect ratio. For FeS.sub.2 nanoparticles of the current invention, nanorods should have an aspect ratio less than 1000, preferably less than 750, preferably less than 500, preferably less than 250, preferably less than 100, preferably less than 75, preferably less than 50, preferably less than 25. Nanorods having an aspect ratio greater than 1000 are typically referred to as nanowires and are not a shape that the FeS.sub.2 nanoparticles are envisioned as having in any embodiments.
(106) In some embodiments, the FeS.sub.2 nanoparticles have uniform shape. Alternatively, the shape may be non-uniform. As used herein, the term uniform shape refers to an average consistent shape that differs by no more than 10%, by no more than 5%, by no more than 4%, by no more than 3%, by no more than 2%, by no more than 1% of the distribution of FeS.sub.2 nanoparticles having a different shape. As used herein, the term non-uniform shape refers to an average consistent shape that differs by more than 10% of the distribution of FeS.sub.2 nanoparticles having a different shape. In one embodiment, the shape is uniform and at least 90% of the FeS.sub.2 nanoparticles are spherical or substantially circular, and less than 10% are polygonal. In another embodiment, the shape is non-uniform and less than 90% of the FeS.sub.2 nanoparticles are spherical or substantially circular, and greater than 10% are polygonal.
(107) In some embodiments, the FeS.sub.2 nanoparticles have a mean particle size of 10 to 1000 nm, preferably 25 to 900 nm, preferably 50 to 800 nm, preferably 75 to 700 nm, preferably 100 to 600 nm, preferably 125 to 500 nm, preferably about 150 to 400 nm, preferably 175 to 300 nm, preferably 200 to 250 nm. In embodiments where the FeS.sub.2 nanoparticles are spherical, the particle size may refer to a particle diameter. In embodiments where the FeS.sub.2 nanoparticles are polyhedral, the particle size may refer to the diameter of a circumsphere. In some embodiments, the particle size refers to a mean distance from a particle surface to particle centroid or center of mass. In alternative embodiments, the particle size refers to a maximum distance from a particle surface to a particle centroid or center of mass. In some embodiments where the FeS.sub.2 nanoparticles have an anisotropic shape such as nanorods, the particle size may refer to a length of the nanorod, a width of the nanorod, or an average of the length and width of the nanorod. In some embodiments in which the FeS.sub.2 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent volume as the particle. In some embodiments in which the FeS.sub.2 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent diffusion coefficient as the particle.
(108) In some embodiments, the FeS.sub.2 nanoparticles of the present disclosure are monodisperse, having a coefficient of variation or relative standard deviation, expressed as a percentage and defined as the ratio of the particle size standard deviation (a) to the particle size mean (p) multiplied by 100 of less than 25%, preferably less than 10%, preferably less than 8%, preferably less than 6%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2%. In some embodiments, the FeS.sub.2 nanoparticles of the present disclosure are monodisperse having a particle size distribution ranging from 80% of the average particle size to 120% of the average particle size, preferably 90-110%, preferably 95-105% of the average particle size. In some embodiments, the FeS.sub.2 nanoparticles are not monodisperse.
(109) In some embodiments, the nanocomposite comprises -Fe.sub.2O.sub.3 nanoparticles. In general, the -Fe.sub.2O.sub.3 nanoparticles can be any shape known to one of ordinary skill in the art. Examples of suitable shapes the -Fe.sub.2O.sub.3 nanoparticles may take include spheres, spheroids, lentoids, ovoids, solid polyhedra such as tetrahedra, cubes, octahedra, icosahedra, dodecahedra, hollow polyhedra (also known as nanocages), stellated polyhedra (both regular and irregular, also known as nanostars), triangular prisms (also known as nanotriangles), hollow spherical shells (also known as nanoshells), tubes (also known as nanotubes), nanosheets, nanoplatelets, nanodisks, rods (also known as nanorods), and mixtures thereof. In the case of nanorods, the rod shape may be defined by a ratio of a rod length to a rod width, the ratio being known as the aspect ratio. For -Fe.sub.2O.sub.3 nanoparticles of the current invention, nanorods should have an aspect ratio less than 1000, preferably less than 750, preferably less than 500, preferably less than 250, preferably less than 100, preferably less than 75, preferably less than 50, preferably less than 25. Nanorods having an aspect ratio greater than 1000 are typically referred to as nanowires and are not a shape that the -Fe.sub.2O.sub.3 nanoparticles are envisioned as having in any embodiments.
(110) In some embodiments, the -Fe.sub.2O.sub.3 nanoparticles have uniform shape. Alternatively, the shape may be non-uniform. As used herein, the term uniform shape refers to an average consistent shape that differs by no more than 10%, by no more than 5%, by no more than 4%, by no more than 3%, by no more than 2%, by no more than 1% of the distribution of -Fe.sub.2O.sub.3 nanoparticles having a different shape. As used herein, the term non-uniform shape refers to an average consistent shape that differs by more than 10% of the distribution of -Fe.sub.2O.sub.3 nanoparticles having a different shape. In one embodiment, the shape is uniform and at least 90% of the -Fe.sub.2O.sub.3 nanoparticles are spherical or substantially circular, and less than 10% are polygonal. In another embodiment, the shape is non-uniform and less than 90% of the -Fe.sub.2O.sub.3 nanoparticles are spherical or substantially circular, and greater than 10% are polygonal.
(111) In some embodiments, the -Fe.sub.2O.sub.3 nanoparticles have a mean particle size of 10 to 1000 nm, preferably 25 to 900 nm, preferably 50 to 800 nm, preferably 75 to 700 nm, preferably 100 to 600 nm, preferably 125 to 500 nm, preferably about 150 to 400 nm, preferably 175 to 300 nm, preferably 200 to 250 nm. In embodiments where the -Fe.sub.2O.sub.3 nanoparticles are spherical, the particle size may refer to a particle diameter. In embodiments where the -Fe.sub.2O.sub.3 nanoparticles are polyhedral, the particle size may refer to the diameter of a circumsphere. In some embodiments, the particle size refers to a mean distance from a particle surface to particle centroid or center of mass. In alternative embodiments, the particle size refers to a maximum distance from a particle surface to a particle centroid or center of mass. In some embodiments where the -Fe.sub.2O.sub.3 nanoparticles have an anisotropic shape such as nanorods, the particle size may refer to a length of the nanorod, a width of the nanorod, or an average of the length and width of the nanorod. In some embodiments in which the -Fe.sub.2O.sub.3 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent volume as the particle. In some embodiments in which the -Fe.sub.2O.sub.3 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent diffusion coefficient as the particle.
(112) In some embodiments, the -Fe.sub.2O.sub.3 nanoparticles of the present disclosure are monodisperse, having a coefficient of variation or relative standard deviation, expressed as a percentage and defined as the ratio of the particle size standard deviation (a) to the particle size mean (p) multiplied by 100 of less than 25%, preferably less than 10%, preferably less than 8%, preferably less than 6%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2%. In some embodiments, the -Fe.sub.2O.sub.3 nanoparticles of the present disclosure are monodisperse having a particle size distribution ranging from 80% of the average particle size to 120% of the average particle size, preferably 90-110%, preferably 95-105% of the average particle size. In some embodiments, the -Fe.sub.2O.sub.3 nanoparticles are not monodisperse.
(113) In some embodiments, the nanocomposite comprises TiO.sub.2 nanoparticles. In general, the TiO.sub.2 nanoparticles can be any shape known to one of ordinary skill in the art. Examples of suitable shapes the TiO.sub.2 nanoparticles may take include spheres, spheroids, lentoids, ovoids, solid polyhedra such as tetrahedra, cubes, octahedra, icosahedra, dodecahedra, hollow polyhedra (also known as nanocages), stellated polyhedra (both regular and irregular, also known as nanostars), triangular prisms (also known as nanotriangles), hollow spherical shells (also known as nanoshells), tubes (also known as nanotubes), nanosheets, nanoplatelets, nanodisks, rods (also known as nanorods), and mixtures thereof. In the case of nanorods, the rod shape may be defined by a ratio of a rod length to a rod width, the ratio being known as the aspect ratio. For TiO.sub.2 nanoparticles of the current invention, nanorods should have an aspect ratio less than 1000, preferably less than 750, preferably less than 500, preferably less than 250, preferably less than 100, preferably less than 75, preferably less than 50, preferably less than 25. Nanorods having an aspect ratio greater than 1000 are typically referred to as nanowires and are not a shape that the TiO.sub.2 nanoparticles are envisioned as having in any embodiments. In some embodiments, the TiO.sub.2 nanoparticles are in the form of two-dimensional (2D) nanosheets. The TiO.sub.2 nanosheets may be shaped like blocks, flakes, ribbons, discs, granules, platelets, angular chunks, rectangular prisms, or some other shape.
(114) In some embodiments, the TiO.sub.2 nanoparticles have uniform shape. Alternatively, the shape may be non-uniform. As used herein, the term uniform shape refers to an average consistent shape that differs by no more than 10%, by no more than 5%, by no more than 4%, by no more than 3%, by no more than 2%, by no more than 1% of the distribution of TiO.sub.2 nanoparticles having a different shape. As used herein, the term non-uniform shape refers to an average consistent shape that differs by more than 10% of the distribution of TiO.sub.2 nanoparticles having a different shape. In one embodiment, the shape is uniform and at least 90% of the TiO.sub.2 nanoparticles are spherical or substantially circular, and less than 10% are polygonal. In another embodiment, the shape is non-uniform and less than 90% of the TiO.sub.2 nanoparticles are spherical or substantially circular, and greater than 10% are polygonal.
(115) In some embodiments, the TiO.sub.2 nanoparticles have a mean particle size of 10 to 1000 nm, preferably 25 to 900 nm, preferably 50 to 800 nm, preferably 75 to 700 nm, preferably 100 to 600 nm, preferably 125 to 500 nm, preferably about 150 to 400 nm, preferably 175 to 300 nm, preferably 200 to 250 nm. In embodiments where the TiO.sub.2 nanoparticles are spherical, the particle size may refer to a particle diameter. In embodiments where the TiO.sub.2 nanoparticles are polyhedral, the particle size may refer to the diameter of a circumsphere. In some embodiments, the particle size refers to a mean distance from a particle surface to particle centroid or center of mass. In alternative embodiments, the particle size refers to a maximum distance from a particle surface to a particle centroid or center of mass. In some embodiments where the TiO.sub.2 nanoparticles have an anisotropic shape such as nanorods, the particle size may refer to a length of the nanorod, a width of the nanorod, or an average of the length and width of the nanorod. In some embodiments in which the TiO.sub.2 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent volume as the particle. In some embodiments where the TiO.sub.2 nanoparticles have an anisotropic shape such as nanosheets, the particle size may refer to a length of the nanosheet, a width of the nanosheet, an average of the length and width of the nanosheet, a thickness of the nanosheet, or an average of the length, width, and thickness of the nanosheet. In some embodiments in which the TiO.sub.2 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent volume as the particle. In some embodiments in which the TiO.sub.2 nanoparticles have non-spherical shapes, the particle size refers to the diameter of a sphere having an equivalent diffusion coefficient as the particle.
(116) In some embodiments, the TiO.sub.2 nanoparticles of the present disclosure are monodisperse, having a coefficient of variation or relative standard deviation, expressed as a percentage and defined as the ratio of the particle size standard deviation (a) to the particle size mean (p) multiplied by 100 of less than 25%, preferably less than 10%, preferably less than 8%, preferably less than 6%, preferably less than 5%, preferably less than 4%, preferably less than 3%, preferably less than 2%. In some embodiments, the TiO.sub.2 nanoparticles of the present disclosure are monodisperse having a particle size distribution ranging from 80% of the average particle size to 120% of the average particle size, preferably 90-110%, preferably 95-105% of the average particle size. In some embodiments, the TiO.sub.2 nanoparticles are not monodisperse.
(117) In some embodiments, the TiO.sub.2 nanoparticles may be present in an amount ranging from 1 to 15 wt. %, 1.25 to 14.5 wt. %, preferably 1.5 to 14 wt. %, preferably 1.75 to 13.5 wt. %, preferably 2 to 13 wt. %, preferably 2.25 to 12.5 wt. %, preferably 2.5 to 12 wt. %, preferably 2.75 to 11.5 wt. %, preferably 3 to 11 wt. % preferably 3.25 to 10.75 wt. %, preferably 3.5 to 10.5 wt. %, preferably 3.75 to 10.25 wt. %, preferably 4 to 10 wt. %, based on the total weight of nanocomposite. In some embodiments, the TiO.sub.2 nanoparticles are present in an amount of 10 wt. %, based on the total weight of nanocomposite. In some embodiments, the TiO.sub.2 nanoparticles are present in an amount of 4 wt. %, based on the total weight of nanocomposite.
(118) In some embodiments, the nanocomposite comprises C.sub.3N.sub.4 nanosheets. In some embodiments, the C.sub.3N.sub.4 nanosheets may consist of stacks of C.sub.3N.sub.4 sheets, the stacks having an average thickness and a diameter. In some embodiments, the stacks comprise 1 to 60 sheets of C.sub.3N.sub.4, preferably 2 to 55 sheets of C.sub.3N.sub.4, preferably 3 to 50 sheets of C.sub.3N.sub.4.
(119) In some embodiments, the C.sub.3N.sub.4 is in the form of C.sub.3N.sub.4 nanosheets. The C.sub.3N.sub.4 nanosheets may be shaped like blocks, flakes, ribbons, discs, granules, platelets, angular chunks, rectangular prisms, or some other shape. For the C.sub.3N.sub.4 nanosheets, a particle size may refer to a length of the nanosheet, a width of the nanosheet, an average of the length and width of the nanosheet, a thickness of the nanosheet, or an average of the length, width, and thickness of the nanosheet.
(120) In some embodiments, the C.sub.3N.sub.4 nanosheets may be present in an amount of from 1 to 15 wt. %, 1.25 to 14.5 wt. %, preferably 1.5 to 14 wt. %, preferably 1.75 to 13.5 wt. %, preferably 2 to 13 wt. %, preferably 2.25 to 12.5 wt. %, preferably 2.5 to 12 wt. %, preferably 2.75 to 11.5 wt. %, preferably 3 to 11 wt. % preferably 3.25 to 10.75 wt. %, preferably 3.5 to 10.5 wt. %, preferably 3.75 to 10.25 wt. %, preferably 4 to 10 wt. %, based on the total weight of nanocomposite. In some embodiments, the C.sub.3N.sub.4 nanosheets are present in an amount of 4 wt. %, based on the total weight of nanocomposite. In some embodiments, the C.sub.3N.sub.4 nanosheets are present in an amount of 10 wt. %, based on the total weight of nanocomposite.
(121) In some embodiments, the nanocomposite is substantially free of C.sub.3N.sub.4 nanosheets.
(122) In general, the particle size may be determined by any suitable method known to one of ordinary skill in the art. In some embodiments, the particle size is determined by powder X-ray diffraction (PXRD). Using PXRD, the particle size may be determined using the Scherrer equation, which relates the full-width at half-maximum (FWHM) of diffraction peaks to the size of regions comprised of a single crystalline domain (known as crystallites) in the sample. In some embodiments, the crystallite size is the same as the particle size. For accurate particle size measurement by PXRD, the particles should be crystalline, comprise only a single crystal, and lack non-crystalline portions. Typically, the crystallite size underestimates particle size compared to other measures due to factors such as amorphous regions of particles, the inclusion of non-crystalline material on the surface of particles such as bulky surface ligands, and particles which may be composed of multiple crystalline domains. In some embodiments, the particle size is determined by dynamic light scattering (DLS). DLS is a technique which uses the time-dependent fluctuations in light scattered by particles in suspension or solution in a solvent, typically water to measure a size distribution of the particles. Due to the details of the DLS setup, the technique measures a hydrodynamic diameter of the particles, which is the diameter of a sphere with an equivalent diffusion coefficient as the particles. The hydrodynamic diameter may include factors not accounted for by other methods such as non-crystalline material on the surface of particles such as bulky surface ligands, amorphous regions of particles, and surface ligand-solvent interactions. Further, the hydrodynamic diameter may not accurately account for non-spherical particle shapes. DLS does have an advantage of being able to account for or more accurately model solution or suspension behavior of the particles compared to other techniques. In some embodiments, the particle size is determined by electron microscopy techniques such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM).
(123) In some embodiments, the nanocomposite has a band gap of from 1.25 to 2.55 eV, preferably 1.30 to 2.50 eV, preferably 1.35 to 2.45 eV, preferably 1.40 to 2.40 eV, preferably 1.45 to 2.35 eV, preferably 1.50 to 2.30 eV, preferably 1.55 to 2.25 eV, preferably 1.60 to 2.20 eV, preferably 1.65 to 2.15 eV.
(124) In some embodiments, the nanocomposite may have an electrochemical surface area (ECSA) of from 13 to 35 mFcm.sup.2, 15 to 33 mFcm.sup.2, preferably 17 to 32 mFcm.sup.2, preferably 19 to 31 mFcm.sup.2, preferably 21 to 30 mFcm.sup.2, preferably 22 to 29 mFcm.sup.2, preferably 23 to 28 mFcm.sup.2, preferably 24 to 27 mFcm.sup.2, preferably 25.0 to 26.5 mFcm.sup.2, preferably 25.5 to 26.0 mFcm.sup.2. In some embodiments, the electrochemical surface area is measured in an aqueous electrolyte solution as described below. In some embodiments, the electrochemical surface area is measured in 1 M KCl.
(125) In some embodiments, the nanocomposite may have a charge transfer resistance (.sub.CT) of 10 to 200, preferably 25 to 175, preferably 50 to 150, preferably 75 to 125, preferably 90 to 110, preferably about 100. In some embodiments, the charge transfer resistance is measured in an aqueous electrolyte solution as described below. In some embodiments, the charge transfer resistance is measured in 1 M KCl. In some embodiments, the nanocomposite may have a
(126) In some embodiments, the nanocomposite may have a saturation magnetization (M.sub.S) ranging from 0.001 to 0.1 emu/g, preferably 0.003 to 0.08 emu/g preferably 0.005 to 0.06 emu/g, preferably 0.007 to 0.04 emu/g, preferably 0.01 to 0.025 emu/g, preferably 0.012 to 0.017 emu/g, preferably 0.014 to 0.015 emu/g. In some embodiments, the nanocomposite may have a remnant magnetization (M.sub.R) ranging from 0.0001 to 0.01 emu/g, preferably 0.0005 to 0.0075 emu/g, preferably 0.001 to 0.005 emu/g, preferably 0.002 to 0.003 emu/g, preferably 0.00225 to 0.00250 emu/g. In some embodiments, the nanocomposite may have a coercivity (H.sub.C) ranging from 500 to 2000 G, preferably 750 to 1750 G, preferably 1000 to 1500 G, preferably 1050 to 1450 G, preferably 1100 to 1400 G, preferably 1150 to 1350 G, preferably 1200 to 1300 G, preferably 1225 to 1250 G. In some embodiments, the nanocomposite may have a ratio of remnant magnetization to saturation magnetization (M.sub.R/M.sub.S) of 0.5 to 3.0, preferably 0.75 to 2.75, preferably 1.0 to 2.5, preferably 1.25 to 2.25, preferably 1.50 to 2.0, preferably 1.75 to 1.90.
(127)
(128) At step 72, the method 70 includes contacting the nanocomposite with an aqueous electrolyte solution. In some embodiments, the aqueous electrolyte solution includes an electrolyte. Examples of electrolytes include, but are not limited to NaCl, KCl, LiCl, MgSO.sub.4, Na.sub.2SO.sub.4, CaCl.sub.2, NH.sub.4NO.sub.3, NaHCO.sub.3, K.sub.2SO.sub.4, H.sub.3PO.sub.4, BaCl.sub.2, NaAc (sodium acetate), KNO.sub.3, MgCl.sub.2, Ca(NO.sub.3).sub.2, Li.sub.2SO.sub.4, Na.sub.3PO.sub.4, (NH.sub.4).sub.2SO.sub.4, NaF, CsCl, and RbCl. In some embodiments, the electrolyte is KCl. In some embodiments, the concentration of KCl ranges from 0.1 to 2 M, preferably 0.25 to 1.75 M, preferably 0.5 to 1.5 M, preferably 0.6 to 1.4 M, preferably 0.75 to 1.25 M, preferably 0.8 to 1.2 M, preferably 0.9 to 1.1 M, preferably about 1 M.
(129) At step 74, the method 70 includes applying a potential of 0.01 to 1.5 V to the nanocomposite and a counter electrode immersed in the aqueous electrolyte solution. In some embodiments, the potential applied to the nanocomposite may range from 0.01 to 1.5 V, preferably 0.25 to 1.45 V, preferably 0.40 to 1.40 V, preferably 0.50 to 1.35 V, preferably 0.60 to 1.30 V, preferably 0.75 to 1.25 V, preferably 0.80 to 1.20 V, preferably 0.85 to 1.15 V, preferably 0.90 to 1.10 V, preferably about 0.93 to 1.09 V.
(130) At step 76, the method 70 includes irradiating the nanocomposite with visible light. In some embodiments, the irradiating source may include but not limited to, mercury vapor lamps, UV-C lamps, metal halide lamps, LED light sources, low-pressure mercury lamps, high-pressure mercury lamps, arc lamps, fluorescent lamps, halogen lamps, carbon arc lamps, incandescent bulbs, near-infrared lasers, UV-LEDs, titanium-dioxide (TiO2) activated lamps, pulsed light sources, microwave plasma sources, solar simulators, cold cathode lamps, sunlight or a xenon and ultraviolet excimer lamps. In a preferred embodiment, the irradiating source is visible lamp.
(131) In some embodiments, the nanocomposite may have an oxygen evolution reaction onset potential ranging from 0.75 to 1.25 V, preferably 0.80 to 1.10 V, preferably 0.85 to 1.00 V, preferably 0.90 to 0.95 V, preferably about 0.93 V, relative to the reversible hydrogen electrode. In some embodiments, the nanocomposite may have a potential required to generate a current density of 10 mAcm.sup.2 (10) ranges from 0.95 to 1.25 V, preferably 1.00 to 1.15 V, preferably 1.05 to 1.10 V, preferably about 1.09 V, relative to the reversible hydrogen electrode.
(132) In some embodiments, the nanocomposite may have a Tafel slope ranging from 37.5 to 65 mV dec.sup.1, 40 to 62.5 mV dec.sup.1, preferably 42.5 to 60 mV dec.sup.1, preferably 45 to 57.5 mV dec.sup.1, preferably 47.5 to 55 mV dec.sup.1, preferably 50 to 52.5 mV dec.sup.1, preferably 51.5 to 51.6 mV dec.sup.1.
(133)
(134) At step 92, the method 90 includes contacting the nanocomposite of with an aqueous electrolyte solution. In some embodiments, the aqueous electrolyte solution includes an electrolyte. Examples of electrolytes include, but are not limited to NaCl, KCl, LiCl, MgSO.sub.4, Na.sub.2SO.sub.4, CaCl.sub.2, NH.sub.4NO.sub.3, NaHCO.sub.3, K.sub.2SO.sub.4, H.sub.3PO.sub.4, BaCl.sub.2, NaAc (sodium acetate), KNO.sub.3, MgCl.sub.2, Ca(NO.sub.3).sub.2, Li.sub.2SO.sub.4, Na.sub.3PO.sub.4, (NH.sub.4).sub.2SO.sub.4, NaF, CsCl, and RbCl. In some embodiments, the electrolyte is KCl. In some embodiments, the concentration of KCl ranges from 0.1 to 2 M, preferably 0.25 to 1.75 M, preferably 0.5 to 1.5 M, preferably 0.6 to 1.4 M, preferably 0.75 to 1.25 M, preferably 0.8 to 1.2 M, preferably 0.9 to 1.1 M, preferably about 1 M.
(135) At step 94, the method 90 includes applying a potential of 1.2 to 0.01 V to the nanocomposite and a counter electrode immersed in the aqueous electrolyte solution. In some embodiments, a potential applied to the nanocomposite may range from 1.2 to 0.01 V, preferably 1.1 to 0.02 V, preferably 1.0 to 0.03 V, preferably 0.9 to 0.04 V, preferably 0.8 to 0.05 V, preferably 0.7 to 0.07 V, preferably 0.6 to 0.08 V, preferably 0.55 to 0.09 V, preferably 0.54 to 0.1 V.
(136) At step 96, the method 90 includes irradiating the nanocomposite with visible light. In some embodiments, the irradiating source may include but not limited to, mercury vapor lamps, UV-C lamps, metal halide lamps, LED light sources, low-pressure mercury lamps, high-pressure mercury lamps, arc lamps, fluorescent lamps, halogen lamps, carbon arc lamps, incandescent bulbs, near-infrared lasers, UV-LEDs, titanium-dioxide (TiO.sub.2) activated lamps, pulsed light sources, microwave plasma sources, solar simulators, cold cathode lamps, sunlight or xenon and ultraviolet excimer lamps. In preferred embodiment, the irradiating source is visible lamp.
(137) In some embodiments, the nanocomposite may have a hydrogen evolution reaction onset potential range from 0.25 to 0.01 V, preferably 0.20 to 0.025 V, preferably 0.175 to 0.05 V, preferably 0.15 to 0.075 V, preferably 0.125 to 0.09 V, preferably 0.1 V relative to the reversible hydrogen electrode.
(138) In some embodiments, the nanocomposite may have a potential required to generate a current density of 10 mAcm.sup.2 (10) ranges from 0.75 to 0.25 V, preferably 0.70 to 0.30 V, preferably 0.65 to 0.40 V, preferably 0.60 to 0.45 V, preferably 0.55 to 0.50 V, preferably 0.54 V relative to the reversible hydrogen electrode.
(139) In some embodiments, the nanocomposite may have a Tafel slope ranging from 40 to 10 mV dec.sup.1, preferably 35.0 to 12.5 mV dec.sup.1, preferably 32.5 to 15.0 mV dec.sup.1, preferably 30.0 to 17.5 mV dec.sup.1, preferably 27.5 to 20.0 mV dec.sup.1, preferably 25.0 to 22.0 mV dec.sup.1, preferably 24.5 to 23.0 mV dec.sup.1, preferably 24.0 to 23.5 mV dec.sup.1, preferably 23.75 to 23.70 mV dec.sup.1, preferably 23.72 mV dec.sup.1.
(140) In some embodiments, the nanocomposite may have a turnover frequency for HER in a range of from 0.20 to 0.40 s.sup.1, preferably 0.21 to 0.38 s.sup.1, 0.22 to 0.36 s.sup.1, preferably 0.23 to 0.35 s.sup.1, preferably 0.24 to 0.34 s.sup.1, preferably 0.25 to 0.33 s.sup.1, preferably 0.26 to 0.32 s.sup.1, preferably 0.27 to 0.31 s.sup.1, preferably 0.28 to 0.30 s.sup.1, preferably 0.29 s.sup.1.
(141) The present disclosure also relates to a method of photodegrading an organic pollutant. In some embodiments, the method includes irradiating with visible light a photodegradation mixture including the nanocomposite, an organic pollutant and an oxidant. In some embodiments, the oxidant may be selected from hydrogen peroxide and a persulfate salt. Examples of persulfate salts include, but are not limited to sodium persulfate, ammonium persulfate, calcium persulfate, magnesium persulfate, lithium persulfate, barium persulfate, strontium persulfate, potassium peroxymonosulfate, sodium peroxymonosulfate, peracetic acid, perpropionic acid, perbenzoic acid, peracetic acid, potassium peroxydisulfate, sodium peroxydisulfate, ammonium peroxydisulfate, lithium peroxydisulfate, calcium peroxydisulfate, and aluminum peroxydisulfate. In some embodiments the persulfate salt is potassium persulfate.
(142) In some embodiments, the organic pollutant is at least one selected from the group consisting of a dye, a phenol, a polycyclic aromatic hydrocarbon, an herbicide, a pesticide, an antibiotic, and a persistent organic pollutant.
(143) In some embodiments, the organic pollutant is a dye. A dye is a colored substance that chemically binds to a material it may be intended to color. Generally, a dye is applied in solution, typically aqueous solution. Examples of dyes include, but are not limited to: acridine dyes, which are acridine and its derivatives such as acridine orange, acridine yellow, acriflavine, and gelgreen; anthraquinone dyes, which are anthroaquinone and its derivatives such as acid blue 25, alizarin, anthrapurpurin, carminic acid, 1,4-diamno-2,3-dihydroanthraquinone, 7,14-dibenzypyrenequinone, dibromoanthrone, 1,3-dihydroxyanthraquinone, 1,4-dihydroxyanthraquinone, disperse red 9, disperse red 11, indanthrone blue, morindone, oil blue 35, parietin, quinizarine green SS, remazol brilliant blue R, solvent violet 13, 1,2,4-trihydroxyanthraquinone, vat orange 1, and vat yellow 1; diaryl methane dyes such as auramine O, triarylmethane dyes such as acid fuchsin, aluminon, aniline blue WS, aurin, aurintricarboxylic acid, brilliant blue FCF, brilliant green, bromocresol green, bromocresol purple, bromocresol blue, bromophenol blue, bromopyrogallol red, chlorophenol red, coomassie brilliant blue, cresol red, O-cresolphthalein, crystal violet, dichlorofluorescein, ethyl green, fast green FCT, FIAsH-EDT2, fluoran, fuchsine, green S, light green SF, malachite green, merbromin, metacresol purple, methyl blue, methyl violet, naphtholphthalein, new fuchsine, pararosaniline, patent blue V, phenol red, phenolphthalein, phthalein dye, pittacal, spirit blue, thymol blue, thymolphthalein, Victoria blue BO, Victoria blue R, water blue, xylene cyanol, and xylenol orange; azo dyes such as acid orange 5, acid red 13, alican yellow, alizarine yellow R, allura red AC, amaranth, amido black 10B, aniline yellow, arylide yellow, azo violet, azorubine, basic red 18, biebrich scarlet, Bismarck brown Y, black 7984, brilliant black BN, brown FK, chrysoine resorcinol, citrus red 2, congo red, D&C red 33, direct blue 1, disperse orange 1, eriochrome black T, evans blue, fast yellow AB, orange 1, hydroxynaphthol blue, janus green B, lithol rubine BK, metanil yellow, methyl orange, methyl red, methyl yellow, mordant brown 33, mordant red 19, naphthol AS, oil red 0, oil yellow DE, orange B, orange G, orange GGN, para red, pigment yellow 10, ponceau 2R, prontosil, red 2G, scarlet GN, Sirius red, solvent red 26, solvent yellow 124, sudan black B, sudan I, sudan red 7B, sudan stain, tartrazine, tropaeolin, trypan blue, and yellow 2G; phthalocyanine dyes such as phthalocyanine blue BN, phthalocyanine Green G, Alcian blue, and naphthalocyanine, azin dyes such as basic black 2, mauveine, neutral red, Perkin's mauve, phenazine, and safranin; indophenol dyes such as indophenol and dichlorophenolindophenol; oxazin dyes; oxazone dyes; thiazine dyes such as azure A, methylene blue, methylene green, new methylene blue, and toluidine blue; thiazole dyes such as primuline, stains-all, and thioflavin; xanthene dyes such as 6-carboxyfluorescein, eosin B, eosin Y, erythosine, fluorescein, rhodamine B, rose bengal, and Texas red; fluorone dyes such as calcein, carboxyfluorescein diacetate succinimidyl ester, fluo-3, fluo-4, indian yellow, merbromin, pacific blue, phloxine, and seminaphtharhodafluor; or rhodamine dyes such as rhodamine, rhodamine 6G, rhodamine 123, rhodamine B, sulforhodamine 101, and sulforhodamine B.
(144) In some embodiments, the organic pollutant is a phenol. A phenol is a compound consisting of a hydroxyl group (OH) bonded directly to an aromatic hydrocarbon group. Examples of phenols include, but are not limited to, phenol (the namesake of the group of compounds), bisphenols (including bisphenol A), butylated hydroxytoluene (BHT), 4-nonylphenol, orthophenyl phenol, picric acid, phenolphthalein and its derivatives mentioned above, xylenol, diethylstilbestrol, L-DOPA, propofol, butylated hydroxyanisole, 4-tert-butylcatechol, tert-butylhydroquinone, carvacrol, chloroxyleol, cresol (including M-, O-, and P-cresol), 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-ethyl-4,5-dimethylphenol, 4-ethylguaiacol, 3-ethylphenol, 4-ethylphenol, flexirubin, mesitol, 1-nonyl-4-phenol, thymol, 2,4,6-tri-tert-butylphenol, chlorophenol (including 2-, 3-, and 4-chlorophenol), dichlorophenol (including 2,4- and 2,6-dichlorophenol), bromophenol, dibromophenol (including 2,4-dibromophenol), nitrophenol, norstictic acid, oxybenzone, and paracetamol (also known as acetoaminophen).
(145) In some embodiments, the organic pollutant is a polycyclic aromatic hydrocarbon. A polycyclic aromatic hydrocarbon (PAH) is an aromatic hydrocarbon composed of multiple aromatic rings. Examples of polycyclic aromatic hydrocarbons include naphthalene, anthracene, phenanthrene, phenalene, tetracene, chrysene, triphenylene, pyrene, pentacene, benzo[a]pyrene, corannulene, benzo[g,h,i]perylene, coronene, ovalene, benzo[c]fluorine, acenaphthene, acenaphthylene, benz[a]anthracene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene, cyclopenta[c,d]pyrene, dibenz[a,h]anthracene, dibenzo[a,e]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, dibenzo[a,l]pyrene, fluoranthene, fluorine, indeno[1,2,3-c,d]pyrene, 5-methylchrysene, naphthacene, pentaphene, picene, and biphenylene.
(146) In some embodiments, the organic pollutant is an herbicide. An herbicide (also known as weedkiller) is a substance that is toxic to plants and may kill, inhibit the growth of, or prevent the germination of plants. Herbicides are typically used to control the growth of or remove unwanted plants from an area of land, particularly in an agricultural context. Examples of herbicides include, but are not limited to, 2,4-D, aminopyralid, chlorsulfuron, clopyralid, dicamba, diuron, glyphosate, hexazinone, imazapic, imazapyr, methsulfuron methyl, picloram, sulfometuron methyl, triclopyr, fenoxaprop, fluazifop, quizalofop, clethodim, sethoxydim, chlorimuron, foramsulfuron, halosulfuron, nicosulfuron, primisulfuron, prosulfuron, rimsulfuron, thofensulfuron, tribenuron, imazamox, imazaquin, flumetsulam, cloransulam, thiencarbazone, fluoxpyr, diflufenzopyr, atrazine, simazine, metribuzin, bromoxynil, bentazon, linuron, glufosinate, clomazone, isoxaflutole, topramezone, mesotrione, tembotrione, acifluorfen, formesafen, lactofen, flumiclorac, flumioxazin, fulfentrazone, carfentrazone, fluthiacet-ethyl, falufenacil, paraquat, ethalfluralin, pendimethalin, trifluralin, butylate, EPTC, ecetochlor, alachlor, metolachlor, dimethenamid, flufenacet, and pyroxasulfone.
(147) In some embodiments, the organic pollutant is a pesticide. A pesticide is a substance meant to prevent, destroy, or control pests including, but not limited to algae, bacteria, fungi, plants, insects, mites, snails, rodents, and viruses.
(148) A pesticide intended for use against algae is known as an algicide. Examples of algicides include benzalkonium chloride, bethoxazin, cybutryne, dichlone, dichlorophen, diuron, endothal, fentin, isoproturon, methabenthiazuron, nabam, oxyfluorfen, pentachlorophenyl laurate, quinoclamine, quinonamid, simazine, terbutryn, and tiodonium.
(149) A pesticide intended for use against bacteria is known as a bactericide. Examples of bactericides include antibiotics such as: aminoglycosides such as amikacin, gentamicin, kanamycin, neomycin, netilmicin, tobramycin, paromomycin, streptomycin, and spectinomycin; ansamycins such as geldanamycin, herbimycin, and rifaximin; carbacephems such as loracarbef; carbapenems such as ertapenem, doripenem, imipenem, and meropenem; cephalosporins such as cefadroxil, cefazolin, cephradine, cephapirin, cephalothin, cephalexin, cefaclor, cefoxitin, cefotetan, cefamandole, cefmetazole, cefonicid, cefprozil, cefuroxime, cefixime, cefdinir, cefditoren, cefoperazone, cefotaxime, cefpodoxime, cefazidime, ceftibuten, ceftizoxime, moxalactam, ceftriaxone, cefepime, cefaroline fosamil, and ceftobiprole; glycopeptides such as teicoplanin, vancomycin, telavancin, dalbavancin, and oritavancin; lincosamides such as clindamycin and lincomycin; lipopeptides such as daptomycin; macrolides such as azithromycin, clarithromycin, erythromycin, roxithromycin, telithromycin, spiramycin, and fidoxamicin; monobactams such as aztreonam; nitrofurans such as furazolidone and nitrofurantoin; oxazolidinones such as linezolid, posizolid, radezolid, and torezolid; penicillins such as amoxicillin, ampicillin, azlocillin, dicloxacillin, flucloxacillin, mezlocillin, methicillin, nafcillin, oxacillin, penicillins (including penicillin G and V), piperacillin, temocillin, and ticarcillin; polypeptides such as bacitracin, colistin, and polymyxin B; quinolones such as ciproflaxacin, enoxacin, gatifloxacin, gemifloxacin, levofloxacin, lomefloxacin, moxifloxacin, nadifloxacin, nalidixic acid, norfloxacin, ofloxacin, trovafloxacin, gepafloxacin, sparfloxacin, and temafloxacin; sulfonamides such as mafenide, sulfacetamide, sulfadiazine, sulfadithoxine, sulfamethizole, sulfamethoxazole, sulfanilamide, sulfasalazine, sulfisoxazole, and sulfonamidochrysoidine; tetracyclines such as demeclocycline, doxycycline, metacycline, minocycline, oxytetracycline, and tetracycline.
(150) A pesticide intended for use against fungi is known as a fungicide. Examples of fungicides include acibenzolar, acypetacs, aldimorph, anilazine, aureofungin, azaconazole, azithiram, azoxystrobin, benalaxyl, benodanil, benomyl, benquinox, benthiavalicarb, binapacryl, biphenyl, bitertanol, bixafen, blasticidin-S, boscalid, bromuconazole, captafol, captan, carbendazim, carboxin, carpropamid, chloroneb, chlorothalonil, chlozolinate, cyazofamid, cymoxanil, cyprodinil, dichlofluanid, diclocymet, dicloran, diethofencarb, difenoconazole, diflumetorim, dimethachlone, dimethomorph, diniconazole, dinocap, dodemorph, edifenphos, enoxastrobin, epoxiconazole, etaconazole, ethaboxam, ethirimol, etridiazole, famoxadone, fenamidone, fenarimol, fenbuconazole, fenfuram, fenhexamid, fenoxanil, fenpropidin, fenpropimorph, ferbam, fluazinam, fludioxonil, flumorph, fluopicolide, fluopyram, fluoroimide, fluoxastrobin, flusilazole, flutianil, flutolain, flopet, fthalide, furalaxyl, guazatine, hexaconazole, hymexazole, imazalil, imibenconazole, iminoctadine, iodocarb, ipconazole, iprobenfos, iprodione, iprovalicarb, siofetamid, isoprothiolane, isotianil, kasugamycin, laminarin, mancozeb, mandestrobin, mandipropamid, maneb, mepanypyrim, mepronil, meptyldinocap, mealaxyl, metominostrobin, metconazole, methafulfocarb, metiram, metrafenone, myclobutanil, naftifine, nuarimol, octhilinone, ofurace, orysastrobin, oxadixyl, oxathiapiprolin, oxolinic acid, oxpoconazole, oxycarboxin, oxytetracycline, pefurazate, penconazole, pencycuron, penflufen, penthiopyrad, phenamacril, picarbutrazox, picoxystrobin, piperalin, polyoxin, probenzole, prochloraz, procymidone, propamocarb, propiconazole, propineb, proquinazid, prothiocarb, prothioconazole, pydiflumetofen, pyraclostrobin, pyrametostrobin, pyraoxystrobin, pyrazophos, pyribencarb, pyributicarb, pyrifenox, pyrimethanil, pyrimorph, pyriofenone, pyroquilon, quinoxyfen, quintozene, sedaxane, silthiofam, simeconazole, spiroxamine, streptomycin, tebuconazole, tebufloquin, teclofthalam, teenazene, terbinafine, tetraconazole, thiabendazole, thifluzamide, thiphanate, thiram, tiadinil, tolclosfos-methyl, folfenpyrid, tolprocarb, tolylfluanid, triadimefon, triadimenol, triazoxide, triclopyricarb, tricyclazole, tridemorph, trifloxystrobin, triflumizole, triforine, validamycin, and vinclozolin.
(151) A pesticide intended for use against plants is known as an herbicide as described above. A pesticide intended for use against insects is known as an insecticide. Examples of insecticides are: organochlorides such as Aldrin, chlordane, chlordecone, DDT, dieldrin, endofulfan, endrin, heptachlor, hexachlorobenzene, lindane, methoxychlor, mirex, pentachlorophenol, and TDE; organophosphates such as acephate, azinphos-methyl, bensulide, chlorethoxyfos, chlorpyrifos, diazinon, chlorvos, dicrotophos, dimethoate, disulfoton, ethoprop, fenamiphos, fenitrothion, fenthion, malathion, methamdophos, methidathion, mevinphos, monocrotophos, naled, omethoate, oxydemeton-methyl, parathion, phorate, phosalone, phosmet, phostebupirim, phoxim, pirimiphos-methyl, profenofos, terbufos, and trichlorfon; carbamates such as aldicarb, bendiocarb, carbofuran, carbaryl, dioxacarb, fenobucarb, fenoxycarb, isoprocarb, methomyl; pyrethroids such as allethrin, bifenthrin, cyhalothrin, cypermethrin, cyfluthrin, deltamethrin, etofenprox, fenvalerate, permethrin, phenothrin, prallethrin, resmethrin, tetramethrin, tralomethrin, and transfluthrin; neonicotinoids such as acetamiprid, clothiandin, imidacloprid, nithiazine, thiacloprid, and thiamethoxam; ryanoids such as chlorantraniliprole, cyanthaniliprole, and flubendiamide.
(152) A pesticide intended for use against mites is known as a miticide. Examples of miticides are permethrin, ivermectin, carbamate insecticides as described above, organophosphate insecticides as described above, dicofol, abamectin, chlorfenapyr, cypermethrin, etoxazole, hexythiazox, imidacloprid, propargite, and spirotetramat.
(153) A pesticide intended for use against snails and other mollusks is known as a molluscicide. Examples of molluscicides are metaldehyde and methiocarb.
(154) A pesticide intended for use against rodents is known as a rodenticide. Examples of rodenticides are warfarin, coumatetralyl, difenacoum, brodifacoum, flocoumafen, bromadiolone, diphacinone, chlorophacinone, pindone, difethialone, cholecalciferol, ergocalciferol, ANTU, chloralose, crimidine, 1,3-difluoro-2-propanol, endrin, fluroacetamide, phosacetim, pyrinuron, scilliroside, strychnine, tetramethylenedisulfotetramine, bromethalin, 2,4-dinitrophenol, and uragan D2.
(155) A pesticide intended for use against viruses is known as a virucide. Examples of virucides are cyanovirin-N, griffithsin, interferon, NVC-422, scytovirin, urumin, virkon, zonroz, and V-bind viricie.
(156) In some embodiments, the organic pollutant is a persistent organic pollutant. A persistent organic pollutant is a toxic chemical that adversely affects human and environmental health, can be transported by wind and water, and can persist for years, decades, or centuries owing to resistance to environmental degradation by natural chemical, biological, or photolytic processes. Persistent organic pollutants are regulated by the United Nations Environment Programme 2001 Stockholm Convention on Persistent Pollutants. Examples of persistent organic pollutants are Aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene, polychlorinated biphenyl (PCBs), dichlorodiphenyltrichloroethane (DDT), dioxins, polychlorinated dibenzofurans, chlordecone, hexachlorocyclohexane (- and -), hexabromodiphenyl ether, lindane, pentachlorobenzene, tetrabromodiphenyl ether, perfluorooctanesulfonic acid, endosulfans, and hexabromocyclododecane.
(157) In some embodiments, the organic pollutant is an antibiotic. In some embodiments, the organic pollutant is ciprofloxacin.
(158) In some embodiments, the nanocomposite may be free flowing or supported on or within a substrate, for example, a column. Examples of supported nanocomposite include materials and geometries where the nanocomposite is supported within a fixed bed, a static packed bed, a fluidized bed, embedded in a porous support (such as a porous polymer matrix or porous inorganic matrix), in or on a ceramic support, in or on a polymer support, or in or on a silica support.
(159) In some embodiments, the nanocomposite is present in the photodegradation mixture in an amount of 0.01 to 0.75 g/100 mL, preferably 0.02 to 0.5 g/100 mL, preferably 0.025 to 0.40 g/100 mL preferably 0.05 to 0.25 g/100 mL preferably 0.075 to 0.125 g/mL, preferably 0.09 to 0.11 g/100 mL, preferably 0.1 g/100 mL, based on a total volume of photodegradation mixture. In some embodiments, the photodegradation mixture comprises water.
(160) In some embodiments, the initial concentration of ciprofloxacin may range from 5 ppm to 100 m, preferably 10 ppm to 50 ppm, preferably 15 ppm to 30 ppm, preferably 20 ppm.
(161) In some embodiments, the nanocomposite may achieve degradation rates ranging from 70% to 99%, preferably 75% to 99%, preferably 80% to 98%, preferably 85% to 97%, preferably 87.5% to 96.5%, preferably 90% to 96%, preferably 92.5 to 95% of an initial amount of organic pollutant within a reaction time of 180 minutes.
EXAMPLES
(162) The following examples demonstrate the material and method of forming nanocomposite using nanoparticles. The examples are provided solely for illustration and are not to be construed as limitations of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure.
Example 1: Fabrication of the Nanocomposite FeS.SUB.2./-Fe.SUB.2.O.SUB.3
(163) A three-hour time for incubation was given to a 0.25 M ferric acetate solution, and a 0.75 M thiourea solution. The reaction was started by combining 25 ml of the ferric acetate solution and 25 ml of the thiourea solution. The reaction mixture was then stirred for thirty minutes. The mixture was then placed in a furnace with a Teflon-coated lid and heated up to 200 C. for 24 hours. The combined FeS.sub.2/-Fe.sub.2O.sub.3 (FeS.sub.2/FeO) mixture was then given time to cool naturally. Further, deionized water was used to thoroughly wash the resulting black, amorphous product before it was given an acetone treatment. Finally, the mixture was put in an airtight container after drying for 12 hours at 100 C.
Example 2: Synthesis of g-C.SUB.3.N.SUB.4 .Nanosheets
(164) g-C.sub.3N.sub.4 nanosheets were synthesized from urea using high temperature heating. In a standard synthesis, 8 g of urea was placed in a crucible using a lid and heated in a muffle oven at 550 C. for a period of two hours at a temperature rise of 4 C. min.sup.1.
Example 3: Sol-Gel Synthesis of 2D TiO.SUB.2 .Nanoparticles
(165) The TiO.sub.2 nanoparticles were synthesized using a sol-gel preparation method. In a typical synthesis, 30 ml of ethanol and 10 ml of titanium isopropoxide (TTIP>98%) were combined and swirled for 60 minutes at 50-60 C. Next, 150 ml of ionized water (DI) and 3 ml of the nitric acid (HNO.sub.3) were combined, and the resulting mixture served as a hydrolysis catalyst that was introduced dropwise to the TTIP and ethanol. This process typically required four hours or more. Following the addition, the liquid was stirred for vigorously for a two-hour period at 60 C., forming a suspension with a high degree of viscosity. The suspension was then annealed at 600 C. for 4 hours and obtained crystalline TiO.sub.2 nanoparticles.
Example 4: Synthesis of Modified Black TiO.SUB.2./C.SUB.3.N.SUB.4
(166) Approximately 4 g of imidazole and titanium dioxide (TiO.sub.2) nanoparticles were mixed and placed in a crucible with three milliliters (mL) of HCl (37%). This mixture was heated for two hours at 350 C. and for one hour at 400 C., each with a rate of heating of 5 C./min.
Example 5: Preparation of FeS.SUB.2./-Fe.SUB.2.O.SUB.3.@2D Materials
(167) Approximately 0.04 g of each g-C.sub.3N.sub.4, TiO.sub.2 and/or TiO.sub.2 black/C.sub.3N.sub.4 were ground to fine powder and then added to 50 mL methanol. After ultrasonic treatment for 2 h, the materials were found to be exfoliated into thin sheets that formed a homogeneous suspension. Then, 0.96 g of FeS.sub.2/-Fe.sub.2O.sub.3 was dispersed in the suspension and stirred for 12 hours. The products were obtained by sedimentation, washed with deionized water, and then dried at 60 C. overnight in an oven. The samples were named, for example, as FeS.sub.2/FeO@10 TiO.sub.2 and FeS.sub.2/FeO@4TiO.sub.2b-C.sub.3N.sub.4, where TiO.sub.2b is designated for black titania.
Example 6: X-Ray Diffraction and Infrared Analyses
(168) The XRD patterns of fabricated FeS.sub.2/FeO and their nanocomposites with the 2D nanomaterials are shown in
(169) The FTIR spectra of fabricated FeS.sub.2/FeO and their nanocomposites with various 2D nanomaterials (TiO.sub.2, C.sub.3N.sub.4, and TiO.sub.2b/C.sub.3N.sub.4), which were captured in the region of 380-3380 cm.sup.1, are displayed in
Example 7. Electron Microscopy Characterization
(170) The TEM images show that the FeS.sub.2/FeO loaded with 4% TiO.sub.2 (
Example 8. Optical Characterization
(171) The UV-Vis spectra (between 200 and 800 nm) of all the manufactured nanocomposites are shown in
(172) Photochemical applications can benefit from a lower band gap since they require less energy for charge transport. On the other hand, excessively small band gap energy may accelerate recombination or unwanted transitions of electrons to sink sites. The -Fe.sub.2O.sub.3 catalyst's narrow band gap of 2.05 eV is comparable to FeS.sub.2/FeO's (2.13 eV), indicating that FeO makes up most of the binary compound. This result leads to an electronic excitation from Fe to Ti, which results in a decrease in the narrowing of the band gap of Fe-doped TiO.sub.2. This may provide a clue about promoting migration and separation of carriers caused by photons, in addition to aiding in the formation of a conduction band at an elevated location. The expansion of the absorption spectra may also be caused by defects associated with transition energy levels. Through the creation of trapped sites and the promotion of a higher exciton recombination velocity, these defects may facilitate the migration of the carrier.
(173) Furthermore, PL spectroscopy is a useful technique to observe the separation efficacy of the photogenerated charges. As seen in
Example 9. X-Ray Photoelectron Spectroscopy Characterization
(174)
(175) As illustrated in
Example 10. Magnetic Characterization
(176) The magnetic properties of the investigated nanophotocatalysts are shown in
(177) TABLE-US-00001 TABLE 1 The magnetic properties of different photocatalysts obtained by vibrating sample magnetometry (VSM). Composite HC MR (0.05 MS (0.05 Name (0.05 G) emu/g) emu/g MR/Ms FeS.sub.2/FeO 387 0.299 1.729 0.173 FeS.sub.2/FeO@ 10TiO.sub.2 406.10 0.577 2.33 0.248 FeS.sub.2/FeO@.sub.4TiO.sub.2 1070 88.46 10.sup.3 0.452 0.0195 FeS.sub.2/FeO@.sub.4TiO.sub.2b-C.sub.3N.sub.4 1227.6 2.49 10.sup.3 14.19 10.sup.3 1.754 FeS.sub.2/FeO@.sub.4C.sub.3N.sub.4 1512 0.1201 0.4632 0.259
Example 11: Photocatalysis Approach to Ciprofloxacin Degradation Using H.SUB.2.O.SUB.2
(178) The photocatalytic degradation action of FeS.sub.2/FeO supported on the 2D TiO.sub.2 at both 4 and 10% loading alongside 4% C.sub.3N.sub.4 and 4% TiO.sub.2b-C.sub.3N.sub.4 towards ciprofloxacin (20 ppm) using H.sub.2O.sub.2 (1.710.sup.4 M) as an oxidizing agent is shown in
(179) A scavenging study (
h.sup.++H.sub.2O.sub.2.fwdarw.O.sub.2.sup.+2H.sup.+(4)
(180) After 5 consecutive runs, the recyclability of the photocatalyst FeS.sub.2/FeO@10TiO.sub.2 was assessed and found to be extremely stable, reaching 98% (
(181) TABLE-US-00002 TABLE 2 The kinetic data of all the synthesized photocatalysts in the presence of H.sub.2O.sub.2 Sample k 10.sup.3 (min.sup.1) R.sup.2 FeS.sub.2/FeO@4% TiO.sub.2 7.5 0.9334 FeS.sub.2/FeO@4% C.sub.3N.sub.4 6.9 0.9384 FeS.sub.2/FeO@4% TiO.sub.2 b/C.sub.3N.sub.4 7.2 0.9262 FeS.sub.2/FeO@10% TiO.sub.2 17.6 0.911
Example 12: Ciprofloxacin Photocatalytic Degradation with Potassium Persulfate
(182) The photocatalytic performance of FeS.sub.2/FeO doped 2D of C.sub.3N.sub.4, TiO.sub.2 and TiO.sub.2b-C.sub.3N.sub.4 at the 4% loading in comparison of 10% 2DTiO.sub.2 toward Ciprofloxacin (20 ppm) degradation is shown in
(183) As temperature rises, S.sub.2O.sub.8 and the FeS.sub.2/FeO@4% TiO.sub.2 catalyst react more quickly, which speeds up the production of oxidizing species like sulfate and hydroxyl free radicals, which are effective at destroying the pharmaceutical. The photocatalytic efficiency increased when the reaction temperatures were raised from 30 to 40 C. because the higher temperatures enhanced the mobility of charge carriers and interface charge transport. As the temperature was raised to 50 C. (
(184) TABLE-US-00003 TABLE 3 The kinetic data of all the synthesized photocatalysts in presence of persulfate Sample k 10.sup.3 (min.sup.1) R.sup.2 (FeS.sub.2/Fe.sub.2O.sub.3)@4% TiO.sub.2 0.8 0.9132 (FeS.sub.2/Fe.sub.2O.sub.3)@4% C.sub.3N.sub.4 5.5 0.9685 (FeS.sub.2/Fe.sub.2O.sub.3)@4% TiO.sub.2 b/C.sub.3N.sub.4 6.7 0.9671 (FeS.sub.2/Fe.sub.2O.sub.3)@10% TiO.sub.2 12.1 0.9187
(185) The energy consumption in kilowatt hours needed for CIP degradation using PPS or H.sub.2O.sub.2 is an essential factor to consider. This parameter is important from an economic standpoint because it has to do with the expenses involved throughout the reaction process. The following formula was used to determine the amount of energy consumed:
E.sub.EO=Pelt1000/V60log C.sub.o/C(5)
(186) Here V is the amount of water (1) in the reactor; t is the duration of the irradiation period (min); C.sub.o is the original pollutant concentration; and C is the final polluting concentration. Pel is the sum of the input power (kW) both stirring and the visible light lamp. For FeS.sub.2/FeO@1 TiO.sub.2, the computed values with H.sub.2O.sub.2 and PPS were 3.2 and 3.5 kWh m.sup.3 oder.sup.1, respectively. This demonstrates that it became more cost-effective to use H.sub.2O.sub.2 rather than PPS.
(187) When examining possible wastewater treatment applications, the catalyst's reliability and reusability are also important to consider. To assess this, stability experiments were conducted on the FeS.sub.2/FeO@10TiO.sub.2 nanocomposite. The outcomes of these stability experiments are shown in
(188) The enhanced degradation efficiency of CIP on FeS.sub.2/FeO@10TiO.sub.2 when using H.sub.2O.sub.2 as an oxidant rather than PPS may be attributed to the nanocomposite, which exposes more active sites to activate the former oxidant and generates more efficacious radicals than the latter. Further, extra OH groups or acidic conditions may provide H.sup.+ ions, which scavenge the sulphate radical and facilitate generating hydrogen sulphate, therefore influencing the degradation activity as shown in formula 6:
(SO.sub.4.sup.+H.sup.++e.sup..fwdarw.HSO.sub.4.sup.(6)
(189) Based on these experimental results, the impressive photoactivity observed for FeS.sub.2/FeO@10TiO.sub.2 may be attributed to several factors. First, the presence of defect Ti.sup.3+ (19%) is higher than any of the nanocomposites, and this exposes higher active sites via, in addition, the exposure of TiOFe bonds released from Fe substitution. Both e.sup./h.sup.+ separation and visible light absorption are improved by this increase in the Ti.sup.3+ ratio. The existence of a phase not observed in the binary with d spacing of 0.56 nm exhibits higher activity than that at 0.64 nm dedicated to the TiO.sub.2b-C.sub.3N.sub.4 nanocomposite. Second, the percentage of Fe.sup.3+ that constituted the highest amount in 10% TiO.sub.2 presented the lowest crystallite diameter and rather advocated the lowest energy gap value (1.68 eV). It also presented the least charges recombination. Third, this nanocomposite shows one of the highest amounts of OH and sulfate groups, as well as the ability to facilitate electron transmission and permeability as deduced from the magnetic properties. The 10TiO.sub.2 catalyst has a larger proportion of Fe.sup.2+ than the 4TiO.sub.2 catalyst, as estimated from XPS results. The impact of solution pH on CIP degradation by the FeS.sub.2/FeO@C.sub.3N.sub.4 nanocomposite in the presence of H.sub.2O.sub.2 is shown in
(190) Using persulfate as an oxidizing agent, FeS.sub.2/FeO@10TiO.sub.2 produced a comparable result, obtaining 88% at pH 3.5 and 78% at pH 9.5 and 6.5. This illustrates how photocatalytic activity increases in acidic environments for both oxidants. Although the experiments presented here were performed in an acidic environment, the generated hydrogen ions did not inhibit the formation of free radicals. Accordingly, the measured ZPC via potentiometric titration route were 2.5 and 2.16 for TiO.sub.2 and C.sub.3N.sub.4 containing photocatalysts, implying that their surfaces contain negative charges. This is likely because the solution pH is less acidic than the ZPC. Since CIP exists at least partially in cationic form (carry positive charges) up to pH 6, an electrostatic interaction may occur between the pharmaceutical CIP with the photocatalyst surface carrying negative charges. This may result in higher photocatalytic degradation at pH 3.5. On the other hand, basic conditions favour the production of the anionic CIP at a pH of 9, causing repulsion and reducing CIP adsorption on the catalyst surface, both of which may have an impact on CIP's photocatalytic degradation.
(191) The ZPC of FeO was 8.2 and decreased to 2.5 upon the incorporation of FeS, indicating that the latter had adsorption and interaction with the former. It is probable that the highest Fe.sup.2+ availability for H.sub.2O.sub.2 breakdown and the consequently high rate of OOH production at pH 3.5 account for the high removal effectiveness of CIP. Accordingly, the improved removal capability of the photocatalyst containing 10% TiO.sub.2 are attributed to the following: (i) OH possesses a significant potential for oxidation-reduction in acidic environments; (ii) the establishment of a significant amount of Fe.sup.2+ in acidic environments can further enhance the efficiency of the Fenton system as shown in formula 7 below; (iii) acidic circumstances can alleviate the passivity formation of film (Fe(OH).sub.3) on the outside surface of TiO.sub.2 and decrease the removal of active sites.
Fe.sup.2++H.sub.2O.sub.2.fwdarw.Fe.sup.3++OH+OH.sup.(7)
(192) The low removal efficacy of CIP at alkaline pH levels may also be because the redox potential of OH has been shown to decrease with rising pH and also excess OH.sup. will react with H.sub.2O.sub.2 to generate O.sub.2 as shown in formula 8 below, influencing the CIP degradation.
OH.sup.+H.sub.2O.sub.2.fwdarw.O.sub.2+H.sub.2O(8)
(193) A mineralization examination was conducted, which was based on the variance of total organic carbon (TOC), in order to further investigate the photocatalytic efficiency of the FeS.sub.2/FeO@10TiO.sub.2 nanocomposite (
(194) As shown in Table 4, the FeS.sub.2/FeO@2D10TiO2 catalyst was found to be superior in degrading CIP under visible light illumination compared to other catalysts like TiO.sub.2/MMT, CuS/Fe.sub.2O.sub.3/Mn.sub.2O.sub.3, CuS/BiVO.sub.4 (0-4), 3D T-Fe.sub.2O.sub.3@ZnO, and g-C.sub.3N.sub.4/RGO/WO.sub.3. The CIP decontamination of the photocatalyst of the present disclosure was accomplished using either PPS or H.sub.2O.sub.2 oxidants. The latter shows the highest removal rate, which is close to 100% at a concentration of 20 ppm. This level of activity surpasses all the identified references, which were limited to concentrations of 10 ppm. Based on this relatively high CIP concentration, the photocatalyst of the present disclosure presented moderate rate constants compared to the reference catalysts. The rate constant of the photocatalyst of the present disclosure was comparable to that of the TiO2/-Fe.sub.2O.sub.3/GO catalyst. However, the photocatalyst of the present disclosure has other distinct advantages over these catalysts. It is more magnetically recyclable, is prepared in a shorter time, was compatible with a higher CIP concentration, and was compatible with a more acidic environment.
(195) TABLE-US-00004 TABLE 4 Comparison of the CIP photodegradation efficiency of the FeS.sub.2/FeO@2D10TiO.sub.2 catalyst with others in the literature. pH and type of Reaction time Rate constant, min.sup.1 light (min), CIP Degradation and (Oxidant Catalyst source conc. efficiency name) Ref. TiO.sub.2/MMT 5, UV 120, 10 ppm 61.70% 0.0069 (H.sub.2O.sub.2) 1 CuS/Fe.sub.2O.sub.3/Mn.sub.2O.sub.3 5.84, - - - 120, 10 ppm 88% 0.10083 (PMS) 2 CuS/BiVO.sub.4 (0 4 0) - - - , 300 W 90, 10 ppm 86.7% 0.02151 3 Xe lamp 3D -Fe.sub.2O.sub.3@ZnO 5.8, 300 W 60, 10 ppm 92.5% 0.0419 4 Xe lamp g-C.sub.3N.sub.4/RGO/WO.sub.3 - - - , 500 W 180, 10 ppm 85% 5 Xe lamp TiO.sub.2/-Fe.sub.2O.sub.3/GO 6.3, Vis 140, 10 ppm 99% 0.019 (H.sub.2O.sub.2) 6 FeS.sub.2/FeO@2D10TiO.sub.2-x 3.5, Vis 120, 20 ppm 100% 0.0176 (H.sub.2O.sub.2) This lamp 90% 0.0121 (PPS) work References: (1) Hassani A, et. al., J Mol Catal A Chem 2015; 409:149-61; (2) Huang Y, et. al., Chem Eng J 2020; 388:124274; (3) Lai C, et. al., Chem Eng J 2019; 358:891-9; (4) Li N, et. al., Chem Eng J January 2017; 308(15):377-85; (5) Deng Y, et. al., J Hazard Mater 2018; 344:758-69; and (6) Wang F, et. al., Chem Eng J March 2020; 384(15):123381, each of which is incorporated herein by reference in its entirety.
(196) The toxicology of CIP at a concentration of 20 ppm as well as when combined with the catalyst FeS.sub.2/FeO@10TiO.sub.2 exposed to light irradiation for 180 min in the presence of both oxidants was assessed for a variety of strands of bacteria and fungi, including E. coli and P. aeruginosa (gram negative), B. subtilis and S. aureus (gram positive), and C. albicans (fungal). It is clear from Table 5 and
(197) TABLE-US-00005 TABLE 5 Toxicity and microbial activity Inhibition Sample E. coli Pseudomonas B. subtilis S. aureus Candida Zone Ciprofloxacin 20 3.4 1.9 3.1 1.8 2.5 Diameter mg/l (Cm) After degradation 0 0 0 0 0 by K.sub.2S.sub.2O.sub.8 After degradation 0 0 0 0 0 by H.sub.2O.sub.2
Example 13: CIP Photodegradation Proposed Mechanism
(198)
E.sub.VB=XE.sub.e+0.5E.sub.g(9)
E.sub.CB=E.sub.VBE.sub.g(10).
(199) The CB and VB of FeS.sub.2/FeO are respectively equal 0.065 eV and +2.19 eV. The 10% TiO.sub.2 catalyst with higher levels of lattice distortion exhibits a higher fraction of Ti.sup.3+ defects, which were previously identified based on XPS data. This increases the nanocomposite's photocatalytic activity and improve photocurrent generation under visible light. Both TiO.sub.2-x and FeS.sub.2/FeO are stimulated to produce electrons and holes on their respective CB and VB when exposed to light. Once on the CB of TiO.sub.2-x, electrons that are photoexcited move to the VB of FeS.sub.2/FeO, and then the light energy that was received gets released as heat during recombination. With an energy gap of 2.13 eV, the latter nanocomposite's CB electrons may react with PPS on its surface to produce SO.sub.4.sup. and .sup.OH (
(200) These experiments demonstrated that .sup.OH and SO.sub.4.sup. were the most active species in the process using both oxidants, according to the reactive species quenching analyses. Molecules of water cannot be directly oxidized to .sup.OH by holes in the VB of TiO.sub.2-x because the potential energy of .sup.OH/H.sub.2O (+2.4 V) is more positive than that of TiO.sub.2-x(+0.15 eV). Due to the higher positive potentials than SO.sub.4.sup.2/SO.sub.4.sup. (2.5-3.1 V), the electrons on the CB of FeS.sub.2/FeO (0.065 V) were incapable of reducing SO.sub.4 to its radical. This precludes the creation of type II mechanisms and supports a conclusion of the Z scheme. As illustrated,
Ti.sup.3++H.sub.2O.sub.2.fwdarw.Ti.sup.4++.sup.OH+OH.sup.(11)
(201) A detectable amount of SO.sub.4.sup.2 has also been found on FeS.sub.2/FeO@10TiO.sub.2, as evidenced by the XPS results, which can be activated by light irradiation or transition metal (Fe.sup.2+) activation to produce SO.sub.4.sup. radicals that, in turn, can be tuned to .sup.OH.
(202) The probable .sup.OH amount produced can follow the following routes:
Fe.sup.2++H.sub.2O.sub.2.fwdarw.Fe.sup.3++2.sup.OH(12)
SO.sub.4.sup.2+H.sub.2O.fwdarw..sup.OH+SO.sub.4.sup.2+H.sup.+(13)
SO.sub.4.sup.2+Fe.sup.2+.fwdarw.SO.sub.4.sup.+H.sub.2O.fwdarw..sup.OH+SO.sub.4.sup.2+H.sup.+(14)
(203)
Example 14: Water Splitting
(204) The Tafel slope and linear sweep voltammetry techniques were used to determine the kinetic parameters of OER and HER for each photocatalyst under visible light illumination. Linear sweep voltammograms (LSVs) were recorded in the potential ranges 0-3.0 V and 1.2-0.0 V for OER and HER, respectively, versus the reversible hydrogen electrode (RHE).
(205) The existence of two oxidation peaks during photoirradiation may be attributable to the transition of Fe sulfides/oxides into metal (oxy)hydroxide during the OER test under oxidizing potentials, while its absence in the dark may indicate the relevance of (oxy)hydroxide moieties to OER. The OER overpotentials for rest of the photocatalysts at a current density of 10 mAcm.sup.2 were in the order; FeS.sub.2/FeO@10% TiO.sub.2 (1.14 V)<FeS.sub.2/FeO@4% C.sub.3N.sub.4 (1.30 V)<FeS.sub.2/FeO@4% TiO.sub.2 (1.33 V)<FeS.sub.2/FeO (1.57 V).
(206) The energetic kinetics of charge transfer across the electrode-electrolyte boundary during OER was examined using the Tafel slope technique (
(207) The highest recorded photocurrent density was 52 mA cm.sup.2 at 0.75 V from the same photoelectrocatalyst (FeS.sub.2/FeO@4% TiO.sub.2b/C.sub.3N.sub.4) towards HER. This photoelectrocatalyst also showed strong activity with an onset potential of 0.1 V against 0.4 V in the dark. It achieved a current density of 10 mA cm.sup.2 with an overpotential of 0.54 V (
(208) It was also noted that TiO.sub.2-x at the 10% loading opens more active sites for accelerating OER and HER than those at the 4% ratio. The constraints on catalytic active sites and effective surface area appear to prevent the binary component of bulk FeS.sub.2/FeO from meeting the necessary conditions for high-efficiency water splitting. Additionally, techniques for enhancing their activity have been created, such as the engineering of morphology, structure, composition, and interface by incorporating 2D.
(209) TABLE-US-00006 TABLE 6 Electrochemical kinetic parameters, EIS and TOF data of all photoelectrocatalysts towards water splitting in 1.0M KCl. FeS.sub.2/ FeS.sub.2/ FeS.sub.2/ FeS.sub.2/ FeS.sub.2/ Fe.sub.2O.sub.3@4% Fe.sub.2O.sub.3@4% black Fe.sub.2O.sub.3@4% Fe.sub.2O.sub.3@ 10% Parameters Fe.sub.2O.sub.3 TiO.sub.2 TiO.sub.2/C.sub.3N.sub.4 C.sub.3N.sub.4 TiO.sub.2 Rs () 34.9 22.8 50 26.45 34.9 Rct () 1068 532 100 473.5 152 Cathodic tafel 25.36 30.83 23.72 28.07 33.15 slope (mv/decade) Anodic tafel slope 62.52 67.18 51.56 63.97 68.5 (mv/decade) (v)@10 mAcm .sup.2 0.719 0.76 0.546 0.626 0.702 (v)@10 mAcm .sup.2 1.57 1.33 1.09 1.30 1.14 Electrochemical 2 11.5 25.9 12.9 16 surface area (mF/cm.sup.2) TOF for HER (s.sup.1) 0.12 0.15 0.29 0.18 0.23
(210) To evaluate the charge transport at the electrode interface, EIS experiments were conducted. Because of the narrow arc radius of the fitted model, which is directly connected to lower charge transfer resistance, the Nyquist plots (
(211) The FeS.sub.2/FeO@4% TiO.sub.2b/C.sub.3N.sub.4 nanocatalyst is estimated to have a charge transfer resistance of 100, significantly lower than that of FeS.sub.2/FeO@10% TiO.sub.2 (150), FeS.sub.2/FeO@4% C.sub.3N.sub.4 (473.5), FeS.sub.2/FeO@4% TiO.sub.2 (532), and FeS.sub.2/FeO (1068). This indicates the structure of the electrocatalyst FeS.sub.2/FeO@4% TiO.sub.2b/C.sub.3N.sub.4 exhibits rapid interfacial electron transfer kinetics, which may potentially account for an increase in the electrocatalytic activity. These findings verify that the interfacial electron-transfer dynamics are significantly increased by the successful bridging of the bimetallic nanoparticle (FeS.sub.2/FeO) and their strong interaction with the TiO.sub.2b-C.sub.3N.sub.4 support. Although the electrode containing C.sub.3N.sub.4 presented lower charge transfer values than the 4% TiO.sub.2 containing electrode as well as FeS.sub.2/FeO, it presented lower OER-HER activity because of the strong e.sup.-h.sup.+ recombination during the visible light illumination, as shown in the PL results.
(212) The difference between the anodic and cathodic currents (ja-jc) obtained at various scan speeds is used to determine the current density change (|j|) (
(213) By employing the turnover frequency (TOF) value for HER in internal activity computations, an expressive analysis of electrochemical activity was accomplished. FeS.sub.2/FeO@4% TiO.sub.2b/C.sub.3N.sub.4 outperformed all other photocatalysts with a TOF of 0.29 s.sup.1, as shown in Table 6. The TOF values decrease in the following order: FeS.sub.2/FeO@4% TiO.sub.2b/C.sub.3N.sub.4>FeS.sub.2/FeO@10% TiO.sub.2>FeS.sub.2/FeO@4% C.sub.3N.sub.4>FeS.sub.2/FeO@4% TiO.sub.2>FeS.sub.2/FeO. By improving electron nanostructures with morphological changes from flat and symmetrical to anisotropic in nature, the electronic configuration is changed, as evidenced magnetism and TEM results. This results in a boosting of the activities of the electrophotocatalyst containing 2D-layered TiO.sub.2b-C.sub.3N.sub.4 and FeS.sub.2/FeO.
(214) The FeS.sub.2/FeO@TiO.sub.2b-C.sub.3N.sub.4 and FeS.sub.2/FeO@10% TiO.sub.2 electrodes have been shown to exhibit significant activity for both OER and HER, indicating that they may be used as effective bi-functional electrodes for overall water splitting in neutral medium. The total water splitting performance of a two-electrode system using the electrocatalysts FeS.sub.2/FeO@TiO.sub.2b-C.sub.3N.sub.4FeS.sub.2/FeO@TiO.sub.2b-C.sub.3N.sub.4 and FeS.sub.2/FeO@10% TiO.sub.2FeS.sub.2/FeO@10% TiO.sub.2 as both cathode and anode in a 1.0 M KCl solution is depicted in
(215) The heterojunction interface of 2D TiO.sub.2-x sheets including FeS.sub.2/FeO showed 100% and 90% photocatalytic efficacies towards CIP degradation with H.sub.2O.sub.2 and PPS, respectively. The increased ability to absorb visible light, the existence of Ti.sup.3+ (19%) defects, electron transport through TiOFe bridges, a smaller band gap (1.68 eV), and the appropriate number of OH groups were found to be contributing factors to this improved performance. According to the Z-scheme mechanism, this synergistic improvement may be a result of successful separation of the photon-generated charge carrier. Furthermore, the FeS.sub.2/FeO@4% TiO.sub.2black-C.sub.3N.sub.4 nanocomposite electrode showed better PEC capabilities than the other nanocomposite materials, according to the PEC water splitting parameters assessment. Its apparent visible light absorption, high electrochemical surface area, rapid charge kinetics, and efficient charge separation at the heterojunction interface are all possible contributing factors to the PEC performance of the nanocomposite. The nanocomposite achieved overpotentials of 0.546 V at 10 mA cm.sup.2 for HER and 1.09 V mV at 10 mA cm.sup.2 for OER. At 10 mA cm.sup.2, the nanocomposite displayed a cell voltage of 1.65 V while retaining 80% stability after 7-8 h. The enhanced PEC activity of the nanocomposite can be attributed to the close interaction between the two different morphologies of FeS.sub.2 and FeO in 2D.
(216) Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.