Method of obtainment of nanomaterials composed of carbonaceous material and metal oxides

Abstract

Method of obtainment of nanomaterials composed of carbonaceous material and metal oxides. The present invention refers to a method of obtainment of nanomaterials composed of two or more components, wherein at least one of these components is a carbonaceous material and at least another of the components is a metal oxide. The method of the present invention permits preparing these nanomaterials in liquid medium at moderate pressures and temperatures, in industrial quantities, and controlling the physicochemical properties of said nanomaterials by means of control of the parameters of synthesis.

Claims

1. A method of obtainment of a nanomaterial, the method comprising the following stages: a) Dissolution of a first metal oxide in a solvent for 1 to 5 hours to provide a first solution; b) Catalysation of the first solution from stage a) by means of ultrasound at a temperature from 30° C. to 60° C. for 1 to 5 hours; c) Addition of a carbonaceous material to the first solution from stage a) and dispersion by means of ultrasound; and d) Addition of an alkaline solution to the first solution from stage c) for the formation of a metal species in the form of nanoparticles.

2. The method-according to claim 1, wherein the first metal oxide is selected from a group consisting of ZnO, Mn.sub.3O.sub.4, Fe.sub.3O.sub.4, CeO.sub.2, MnO.sub.2, FeO, Fe.sub.2O.sub.3, WO.sub.3, SnO.sub.2, RuO.sub.2, Co.sub.3O.sub.4, and combinations thereof.

3. The method according to claim 1, wherein the carbonaceous material is selected from a group consisting of graphene, nanoplatelets of graphene, graphene oxide, reduced graphene oxide, graphite, graphite oxide, nanotubes of carbon, nanofibres of carbon, and activated carbon.

4. The method according to claim 1, wherein the solvent of stage a) is a mixture of water and an organic acid.

5. The method according to claim 4, wherein the mixture of water and organic acid is in a molar proportion of 1:6.

6. The method according to claim 4, wherein the organic acid is malonic, citric or oxalic acid.

7. The method according to claim 1, wherein the solvent of stage a) is a deep eutectic solvent.

8. The method according to claim 7, wherein the deep eutectic solvent is formed by a mixture of at least one hydrogen bond donor and one quaternary ammonium.

9. The method according to claim 8, wherein the hydrogen bond donor is malonic acid and the quaternary ammonium is choline chloride.

10. The method according to claim 1, wherein stages a) and b) are repeated with a second metal oxide to provide a second solution.

11. The method according to claim 10, wherein the second metal oxide is selected from a group consisting of ZnO, Mn.sub.3O.sub.4, Fe.sub.3O.sub.4, CeO.sub.2, MnO.sub.2, FeO, Fe.sub.2O.sub.3, WO.sub.3, SnO.sub.2, RuO.sub.2, Co.sub.3O.sub.4, and combinations thereof.

12. The method according to claim 10, wherein the first and second solutions of the first and second metal oxides are mixed and homogenised for the purpose of subsequently carrying out stages c) and d) according to the method described in claim 1.

13. The method according to claim 1, wherein the alkaline solution includes hydroxide.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Having the objective of facilitating the comprehension of the invention, in an illustrative but not limitative manner, manners of embodiment of the invention shall be described below making reference to a series of figures.

(2) FIG. 1. Electron microscopy image of a nanomaterial composed of graphene and nanoparticles of Mn.sub.3O.sub.4.

(3) FIG. 2. Electron microscopy images of a nanomaterial composed of active carbon and nanoparticles of Mn.sub.3O.sub.4.

(4) FIG. 3. Electron microscopy image of a nanomaterial composed of graphene and nanoparticles of Mn.sub.3O.sub.4 and Fe.sub.3O.sub.4.

(5) FIG. 4. Electron microscopy image of a nanomaterial composed of graphene and nanoparticles of ZnO.

(6) FIG. 5. Electron microscopy image of a nanomaterial composed of graphene and nanoparticles of Mn.sub.3O.sub.4 and ZnO.

(7) FIG. 6. Electron microscopy image of a nanomaterial composed of graphene and nanoparticles of Mn.sub.3O.sub.4 and Ag.

(8) FIG. 7. Electron microscopy image of a nanomaterial composed of activated carbon and nanoparticles of Mn.sub.3O.sub.4 and Fe.sub.3O.sub.4.

(9) FIG. 8. Electron microscopy image of a nanomaterial composed of graphene/nanotubes of carbon/Mn.sub.3O.sub.4/Fe.sub.3O.sub.4.

DESCRIPTION OF METHODS OF EMBODIMENT

Example 1

Preparation of Graphene/Mn.SUB.3.O.SUB.4 .Composite

(10) 60 mg of Mn.sub.3O.sub.4 (Sigma-Aldrich product number 377473) were added to 40 ml of a solvent composed of a mixture of malonic acid and water in a 1:6 molar ratio. The mixture was subjected to ultrasonic treatment for 1 hour in a sonication bath until dissolution.

(11) 60 mg of nanoplatelets of graphene (GrapheneTech product number GP500 801282-5) were then added and the resulting mixture was again homogenised in an ultrasonic bath for a further 1 hour.

(12) 500 ml of NaOH (VWR product number 28240.361) 1M was then added at a rate of 6.4 ml/minute whilst the suspension was stirred upon a stirrer plate. The mixture was stirred for a further 30 minutes and was filtered under vacuum through a nylon membrane (0.45 micrometers). The residue was washed with 100 ml of distilled water and then with 100 ml of absolute ethanol and was dried in an oven at 100° C. for 12 hours, there being obtained 120 mg of a dark grey powder. For the analysis of the sample, one milligram of said powder was taken and was dispersed in 5 ml of absolute ethanol during 15 minutes of sonication. Some drops of said dispersion were taken and were added upon a grid of copper coated with carbon and were observed by means of transmission electron microscopy (TEM). The image is shown in FIG. 1.

Example 2

Preparation of Graphene/Mn.SUB.3.O.SUB.4./Fe.SUB.3.O.SUB.4 .Composite

(13) 20 mg of Fe.sub.3O.sub.4 (Sigma-Aldrich 637106) were added to a previously prepared mixture composed of choline chloride and malonic acid in a 1:6 molar ratio. The whole was submitted to ultrasound for 20 hours in a sonication bath until dissolution.

(14) In addition, a mixture was prepared composed of malonic acid and water in a 1:6 molar ratio, whereto 30 mg of Mn.sub.3O.sub.4 (Sigma-Aldrich 377473) were added and were dissolved following 1 hour of ultrasonic treatment in a sonication bath.

(15) Both solutions were mixed by means of sonication for a further 1 hour in an ultrasonic bath and following this period 50 mg of graphene nanoplatelets (Graphene-Tech product number GP500 801282-5) were added and the resultant mixture was again homogenised in an ultrasonic bath for a further 1 hour.

(16) 40 ml of an aqueous solution of NaOH (VWR product number 28240.361) 1M were then added, whereafter an additional 400 ml of an aqueous solution of NaOH 5M were added. Following stirring the mixture, the resultant solid was filtered under vacuum, washed with distilled water and then with 100 ml of absolute ethanol and it was dried in an oven at 100° C. for 12 hours, there being obtained 100 mg of a dark grey powder. The sample was analysed by scanning electron microscopy (SEM), utilising therefore 5 mg of material without modification. The image is shown in FIG. 3.

Example 3

Preparation of Graphene/ZnO Composite

(17) Firstly, a solution was prepared composed by a mixture of malonic acid and water in a 1:6 molar proportion. Subsequently 60 mg of ZnO (Aldrich 14439) were added to 30 ml of said solution and the mixture was submitted to ultrasound for 90 minutes in an ultrasonic bath. 60 mg of graphene nanoplatelets (Graphene-Tech product number GP500 801282-5) were then added and the resulting mixture was again homogenised in an ultrasonic bath for a further 90 minutes.

(18) 400 ml of a solution of NaOH 1M were added until pH 12, under constant stirring, followed by 1 hour of sonication in an ultrasonic bath. Finally, the mixture was filtered, washed with distilled water and ethanol and dried in an oven for 12 hours at 100° C., there being obtained 99.5 mg of a black material.

(19) For the analysis of the sample, one milligram of said powder was taken and was dispersed in 5 ml of absolute ethanol by means of 15 minutes sonication. A few drops of said dispersion were taken and were added upon a grid of copper coated with carbon and were observed by means of transmission electron microscopy (TEM). The image is shown in FIG. 4.

Example 4

Preparation of Graphene/Mn.SUB.3.O.SUB.4./ZnO Composite

(20) 50 mg of ZnO were added to 20 ml of a solvent formed by a mixture of malonic acid and water in a 1:6 molar proportion. In a similar and independent manner, 30 mg of Mn.sub.3O.sub.4 were added to 20 ml of a solvent identical to the foregoing one. Both mixtures were sonicated in an independent manner in an ultrasonic bath for 1 h until completion of dissolution of the metal oxides.

(21) Both solutions were then mixed and 80 mg of graphene nanoplatelets were added. The new mixture was sonicated for a further 1 hour and 100 ml of a solution of NaOH 5M were then added under mechanical stirring with a magnetic rod.

(22) When the pH of the mixture attained a value of 12, the solid present in the medium was separated by filtration under vacuum, it was washed with distilled water, ethanol. Finally, it was dried in an oven at 100° C. for 12 hours, there being obtained 157 mg of a dark material.

(23) For the analysis of the sample, one milligram of said powder was taken and was dispersed in 5 ml of absolute ethanol by means of 15 minutes sonication. A few drops of said dispersion were taken and were added upon a grid of copper coated with carbon and were observed by means of transmission electron microscopy (TEM). The image is shown in FIG. 5.

Example 5

Preparation of Graphene/Mn.SUB.3.O.SUB.4./Ag Composite

(24) 30 mg of Mn.sub.3O.sub.4 were added to a 30 ml of a solution composed of a mixture of malonic acid and water in a 1:6 molar proportion and the mixture was sonicated in an ultrasonic bath for 2 hours. 15.75 mg of AgNO.sub.3 were then added to the mixture and were dissolved whilst ultrasound was applied for a further 30 minutes.

(25) 50 mg of graphene nanoplatelets (Graphene-Tech product number GP500 801282-5) were added to the foregoing mixture and the entire system was sonicated for a further hour.

(26) A magnetic rod was incorporated into the mixture and it was stirred whilst 25 mg of NaBH.sub.4 were slowly added. After 30 minutes, 300 ml of an NaOH solution 1M were added until an alkaline pH. Finally, the solid present in the mixture was filtered under vacuum, it was washed with distilled water and ethanol and was dried in an oven at 100° C. for 12 hours.

(27) The resulting mixture was filtered under vacuum and the solid obtained was washed with distilled water and ethanol and was finally dried at 100° C. for 12 h. For the analysis of the sample, one milligram of said powder was taken and was dispersed in 5 ml of absolute ethanol by means of 15 minutes sonication. A few drops of said dispersion were taken and were added upon a grid of copper coated with carbon and were observed by means of transmission electron microscopy (TEM). The image is shown in FIG. 6.

Example 6

Preparation of Active Carbon/Mn.SUB.3.O.SUB.4./Fe.SUB.3.O.SUB.4 .Composite

(28) 30 mg of Mn.sub.3O.sub.4 and 20 mg of Fe.sub.3O.sub.4 were added to an aqueous solution of oxalic acid 0.1 M and the mixture was subjected to sonication in an ultrasonic bath for approximately one hour until all the solid material was completely dissolved. 50 mg of activated carbon (Haycarb HCE 202) were then added to the foregoing mixture and the whole was sonicated for a further 30 minutes. Subsequently, 10 ml of an aqueous solution of NaOH 5M were then added slowly to the mixture whilst the whole was vigorously stirred with a magnetic rod.

(29) Finally, the mixture was filtered under vacuum, there being obtained a dark material which was washed with distilled water, ethanol and was dried in an oven at 100° C.

(30) The sample was analysed by scanning electron microscopy (SEM), utilising for the purpose 5 mg of material without modification. The image is shown in FIG. 7.

Example 7

Preparation of Graphene/Nanotubes of Carbon/Mn.SUB.3.O.SUB.4./Fe.SUB.3.O.SUB.4 .Composite

(31) 30 mg of Mn.sub.3O.sub.4 and 20 mg of Fe.sub.3O.sub.4 were added to an aqueous solution of oxalic acid 0.1 M and the mixture was subjected to sonication in an ultrasonic bath, for approximately one hour, until all the solid material was completely dissolved. 30 mg of nanoplatelets of graphene (GrapheneTech product number GP500 801282-5) and 20 mg of nanotubes of carbon (Carbon Solutions, Inc. AP-SWNT) were then added to the foregoing mixture and the whole was sonicated for a further 30 minutes. Subsequently, 10 ml of an aqueous solution of NaOH 5M were then added slowly to the mixture whilst the whole was vigorously stirred with a magnetic rod.

(32) Finally, the mixture was filtered under vacuum, there being obtained a dark material which was washed with distilled water, ethanol and was dried in an oven at 100° C.

(33) The sample was analysed by scanning electron microscopy (SEM), utilising for the purpose 5 mg of material without modification. The image is shown in FIG. 8.

Example 8

Preparation of Graphene Oxide/Mn.SUB.3.O.SUB.4 .Composite

(34) 40 mg of Mn.sub.3O.sub.4 were added to a solution composed of a mixture of malonic acid and water in a 1:6 molar proportion and the mixture was submitted to sonication in an ultrasonic bath for approximately one hour until complete dissolution of the solid. 10 ml of a suspension of graphene oxide having a concentration of 4 g/l (Graphenea Graphene Oxide GO) were then added to said mixture and the whole was subjected to sonication for a further hour in an ultrasonic bath. In the following stage 150 ml of an aqueous solution of NaOH 5 M were added and the mixture was again sonicated for a further 1 hour. Finally, the solid present in the medium was separated by filtration under vacuum, it was washed with distilled water and ethanol and it was dried in an oven at 100° C., there being obtained 79 mg of a solid black material.

Example 9

Preparation of Reduced Graphene Oxide/Mn.SUB.3.O.SUB.4 .Composite

(35) 75 mg of Mn.sub.3O.sub.4 were added to a solution composed of a mixture of malonic acid and water in a 1:6 molar proportion and the mixture was sonicated in an ultrasonic bath for approximately one hour until complete dissolution of the oxide. 70 mg of reduced graphene oxide (Graphenea Reduced Graphene Oxide rGO) were then added and the mixture was sonicated for a further hour. 150 ml of an aqueous solution of NaOH 5 M were then added and entire mixture was stirred with a magnetic rod for a further hour. The resultant solid was separated by filtration under vacuum, it was washed with distilled water and ethanol and it was dried in an oven at 100° C., there being obtained 149.5 mg of a dark solid material.