NITROGEN-SULFUR CO-DOPED TI3C2-MXENE NANOSHEET AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

The present invention discloses a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet and a preparation method and application thereof. Ti.sub.3C.sub.2-MXene is obtained by etching ternary layered carbides of MAX phase through hydrofluoric acid; and then, the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet is synthesized by a simple one-step method by taking thiourea as a heteroatom source. The nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has a unique two-dimensional layered structure, large specific surface area and abundant heteroatomic catalytic activity sites so that the material presents excellent peroxidase-like activity. The method of the present invention can successfully dope two elements of nitrogen and sulfur in one step on Ti.sub.3C.sub.2-MXene, and can effectively overcome the tedious problem of a step-by-step doping step and the secondary pollution problem of different doping sources to endow peroxidase-like activity for Ti.sub.3C.sub.2-MXene.

Claims

1. A nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet, wherein the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet is prepared by a one-step method with thiourea as a source of heteroatom doping; the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has an organ-shaped layered structure with a thickness of 6-10 μm, and doped elements are evenly distributed on the nanosheet

2. The nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet according to claim 1, wherein the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has peroxidase-like activity.

3. A preparation method of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet of claim 1, the method specifically comprising the following steps: S1 slowly adding MAX phase ceramic powder to hydrofluoric acid, and stirring by magnetic force at room temperature to react after the reaction, washing and centrifuging a corrosion product, washing with absolute ethanol for 3-8 times; and finally, drying the product in a vacuum oven to obtain a Ti.sub.3C.sub.2-MXene nanosheet; S2 grinding and evenly mixing the Ti.sub.3C.sub.2-MXene nanosheet obtained in step 1) and thiourea; then roasting the mixture in an Ar gas atmosphere furnace, and then cooling in the furnace to room temperature; grinding the product again, and centrifugally washing the product with deionized water; and finally drying the product to obtain the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet

4. The preparation method of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet according to claim 3, wherein in step 1), the reaction mass ratio of the MAX phase ceramic powder and the hydrofluoric acid is 1:4 to 1:8, stirring reaction time is 8-24 h, and a stirring rate is 500-1000 r/min.

5. The preparation method of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet according to claim 3, wherein drying temperature in the vacuum oven is 40° C.-80° C., and drying time is 8-16 h.

6. The preparation method of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet according to claim 3, wherein in step 2), the mixing mass ratio of the Ti.sub.3C.sub.2-MXene nanosheet and the thiourea is (¼-½): 1, roasting temperature is 300° C.-700° C., and temperature retention time is 4-8 h.

7. An application of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet of claim 1 in a method for detecting uric acid through simulation of peroxidase activity.

8. The application according to claim 7, wherein the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has peroxidase-like activity, and the method for detecting uric acid is a colorimetric detection method.

9. The application according to claim 8, wherein the colorimetric detection method for uric acid comprises the following steps: successively adding a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet, a uric acid solution, a hydrogen peroxide solution and TMB into disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system and incubating in a water bath; then determining the UV-VIS absorption spectrum of the mixed solution; and recording absorbance, at a wavelength of 652 nm.

10. The application according to claim 9, wherein after mixing, the incubation temperature of the reaction system is 30-50° C., and reaction time is 5-20 min; and the concentration of the uric acid solution in the reaction system is 5 μM, 10 μM, 80 μM, 100 μM, 150 μM, 250 μM, 300 μM, 350 μM or 400 μM.

11. An application of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet prepared by the method of claim 3 in a method for detecting uric acid through simulation of peroxidase activity.

Description

DESCRIPTION OF DRAWINGS

[0035] To more clearly describe the technical solutions in the embodiments of the present invention or in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be simply presented below. Apparently, the drawings in the following description are merely the embodiments of the present invention, and for those ordinary skilled in the art, other drawings can also be obtained according to the provided drawings without contributing creative labor.

[0036] FIG. 1 shows an SEM diagram of a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet in embodiment 1 of the present invention;

[0037] FIG. 2 shows XPS spectrograms of a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet in embodiment 1 of the present invention, wherein (a) XPS full spectrum; (b) C is fine spectrum; (c) N Is fine spectrum; (d) S 2p fine spectrum;

[0038] FIG. 3 shows UV-VIS absorption spectra of different reaction systems in embodiment 1 of the present invention;

[0039] FIG. 4 shows the steady-state kinetic determination of a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet with TMB as substrate in embodiment 1 of the present invention;

[0040] FIG. 5 shows the steady-state kinetic determination of a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet with H.sub.2O.sub.2 as substrate in embodiment 1 of the present invention;

[0041] FIG. 6 shows (a) uric acid concentration-absorbance UV spectrum and (b) uric acid concentration-absorbance standard curve diagram in embodiment 2 of the present invention; and

[0042] FIG. 7 shows a selective experimental diagram of a sensing platform for uric acid in embodiment 2 of the present invention.

DETAILED DESCRIPTION

[0043] The technical solution in the embodiments of the present invention will be clearly and fully described below in combination with the drawings in the embodiments of the present invention. Apparently, the described embodiments are merely part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those ordinary skilled in the art without contributing creative labor will belong to the protection scope of the present invention.

[0044] Embodiments of the present invention disclose a method for detecting uric acid through simulation of peroxidase activity based on a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet. The method not only can successfully dope two elements of nitrogen and sulfur in one step on Ti.sub.3C.sub.2-MXene and can effectively overcome the tedious problem of a step-by-step doping step and the secondary pollution problem of different doping sources to endow peroxidase-like activity for Ti.sub.3C.sub.2-MXene, but also can solve the problems of high cost, long cycle and high operation difficulty of traditional uric acid detection methods and has the advantages of convenience, rapidness, accuracy, high efficiency and low cost. The detection range of uric acid is 5-400 μM. The method can realize accurate quantitative detection in actual samples, and has wide application prospects.

[0045] To better understand the present invention, the present invention is further described in detail below by the following embodiments, but shall not be interpreted as a limitation to the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the contents of the present invention shall also be deemed to fall within the protection scope of the present invention,

[0046] The technical solution of the present invention is further described below in combination with specific embodiments.

Embodiment 1

[0047] A method for detecting uric acid through simulation of peroxidase activity based on, a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet comprises the following steps:

1) Preparation of Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0048] slowly adding 5 g of MAX phase ceramic powder into 50 mL of hydrofluoric acid with mass fraction of 40%, and carrying out a reaction for 24 h at room temperature by magnetic stirring at a stirring speed of 800 r/min; after the reaction, washing and centrifuging a corrosion product till pH of supernate is greater than 6; washing with absolute ethanol for 5 times; and finally, placing the product in a vacuum oven of 60° C. for 12 h to obtain a Ti.sub.3C.sub.2-MXene nanosheet.

2) Preparation of Nitrogen-Sulfur Co-Doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0049] grinding and evenly mixing the Ti.sub.3C.sub.2-MXene nanosheet obtained in step 1) and thiourea according to a mass ratio of 1: 3; then, heating the mixture in an Ar gas atmosphere furnace to 500° C.; after heat preservation for 4 h, cooling in the furnace to room temperature; grinding the product again, and centrifuging with deionized water till the pH value of the supernate is close to 7; and finally drying the product to obtain the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet.

3) Peroxidase-like Activity of Nitrogen-Sulfur Co-Doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0050] successively adding 100 μL of TMB solution (20 mM), 100 μL of hydrogen peroxide solution (50 mM) and 100 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.2 mg/mL) into 1700 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system; after reaction for 10 min, determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording an absorbance value at a wavelength of 652 nm.

4) Colorimetric Detection for Uric Acid

[0051] successively adding 100 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.2 mg/mL), 100 μL of uric acid solution (100 μM), 50 μL of hydrogen peroxide solution (50 mM) and 100 μL of TMB (20 mM) into 1600 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system and incubating in a water bath of 40° C. for 10 min; determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording the absorbance at a wavelength of 652 nm.

Embodiment 2

[0052] A method for detecting uric acid through simulation of peroxidase activity based on a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet comprises the following steps:

1) Preparation of Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0053] slowly adding 8g of MAX phase ceramic powder into 80mL of hydrofluoric acid with mass fraction of 50%, and carrying out a reaction for 12h at room temperature by magnetic stirring at a stirring speed of 1000 r/min; after the reaction, washing and centrifuging a corrosion product till pH of supernate is greater than 6; washing with absolute ethanol for 5 times; and finally, placing the product in a vacuum oven of 80° C. for 15h to obtain a Ti.sub.3C.sub.2-MXene nanosheet.

2) Preparation of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0054] grinding and evenly mixing the Ti.sub.3C.sub.2-MXene nanosheet obtained in step 1) and thiourea according to a mass ratio of 1: 2 then heating the mixture in an Ar gas atmosphere furnace to 600° C.; after heat preservation for 5 h, cooling in the furnace to room temperature; grinding the product again, and centrifuging with deionized water till the pH value of the supernate is close to 7; and finally drying the product to obtain the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet

3) Peroxidase-like Activity of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0055] successively adding 50 μL of TMB solution (10 mM), 50 μL of hydrogen peroxide solution (50 mM) and 100 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.5 mg/mL) into 1850 μL, of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system; after reaction for 15 min, determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording an absorbance value at a wavelength of 652 nm.

4) Colorimetric Detection for Uric Acid

[0056] successively adding 50 μL, of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.5 mg/mL), 50 μL, of uric acid solution (200 μM), 50 μL of hydrogen peroxide solution (40 mM) and 50 μL of TMB (10mM) into 1800 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system and incubating in a water bath of 50° C. for 15 min; determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording the absorbance at a wavelength of 652 nm.

Embodiment 3

[0057] A method for detecting uric acid through simulation of peroxidase activity based on a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet comprises the following steps:

1) Preparation of Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0058] slowly adding 6 g of MAX phase ceramic powder into 70 mL of hydrofluoric acid with mass fraction of 50%, and carrying out a reaction for 12 h at room temperature by magnetic stirring at a stirring speed of 1000 r/min; after the reaction, washing and centrifuging a corrosion product till pH of supernate is greater than 6; washing with absolute ethanol for 7 times; and finally, placing the product in a vacuum oven of 80° C. for 15 h to, obtain a Ti.sub.3C.sub.2-MXene nanosheet

2) Preparation of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0059] grinding and evenly mixing the Ti.sub.3C.sub.2-MXene nanosheet obtained in step 1) and thiourea according to a mass ratio of 1: 4; then heating the mixture in an Ar gas atmosphere furnace to 550° C.; after heat preservation for 8 h, cooling in the furnace to room temperature; grinding the product again, and centrifuging with deionized water till the pH value of the supernate is close to 7; and finally drying the product to obtain the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet.

3) Peroxidase-like Activity of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0060] successively adding 50 of TMB solution (10 mM), 50 μL, of hydrogen peroxide solution (50 mM) and 100 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.4 mg/mL) into 1850 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system; after reaction for 20 min. determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording an absorbance value at a wavelength of 652 nm.

4) Colorimetric Detection for Uric Acid

[0061] successively adding 50 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.5 mg/mL), 50 μL of uric acid solution (200 μM), 50 of hydrogen peroxide solution (40 mM) and 50 μL of TMB (10 mM) into 1800 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system and incubating in a water bath of 50° C. for 15 min; determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording the absorbance at a wavelength of 652 nm.

Embodiment 4

[0062] A method for detecting uric acid through simulation of peroxidase activity based on a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet comprises the following steps:

1) Preparation of Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0063] slowly adding 4g of MAX phase ceramic powder into 50 mL of hydrofluoric acid with mass fraction of 50%, and carrying out a reaction for 8h at room temperature by magnetic stirring at a stirring speed of 1000 r/min; after the reaction, washing and centrifuging a corrosion product till pH of supernate is greater than 6; washing with absolute ethanol for 7 times; and finally, placing the product in a vacuum oven of 60° C. for 10 h to obtain a Ti.sub.3C.sub.2-MXene nanosheet.

2) Preparation of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0064] grinding and evenly mixing the Ti.sub.3C.sub.2-MXene nanosheet obtained in step 1) and thiourea according to a mass ratio of 1: 4; then heating the mixture in an Ar gas atmosphere furnace to 600° C.; after heat preservation for 8 h, cooling in the furnace to room temperature; grinding the product again, and centrifuging with deionized water till the pH value of the supernate is close to 7; and finally drying the product to obtain the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet.

3) Peroxidase-like Activity of Nitrogen-Sulfur Co-doped Ti.SUB.3.C.SUB.2.-MXene Nanosheet

[0065] successively adding 50 μL of TMB solution (10 mM), 50 μL of hydrogen peroxide solution (50 mM) and 100 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.3 mg/mL) into 1850 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system; after reaction for 10 min, determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording an absorbance value at a wavelength of 652 nm.

4) Colorimetric Detection for Uric Acid

[0066] successively adding 50 μL of nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet (0.5 mg/mL), 50 μL of uric acid solution (200 μM), 50 μL of hydrogen peroxide solution (40 mM) and 50 μL of TMB (10 mM) into 1800 μL of disodium hydrogen phosphate-citrate buffer; evenly mixing a reaction system and incubating in a water bath of 50° C. for 15 min; determining the UV-VIS absorption spectrum of the mixed solution with an ultraviolet-visible spectrophotometer; and recording the absorbance at a wavelength of 652 nm.

[0067] The contents of the present invention are not limited to the contents of the above embodiments, and a combination of one or more embodiments can also achieve the purposes of the present invention.

[0068] In order to further verify the excellent effects of the present invention, the inventors also conduct the following experiment.

[0069] FIG. 1 shows an SEM diagram of a Ti.sub.3C.sub.2-MXene nanosheet prepared in embodiment 1. It can be seen that the Ti.sub.3C.sub.2-MXene nanosheet has an organ-shaped layered structure with a thickness of about 8 μm, and layer spacings are evenly distributed.

[0070] FIG. 2 shows XPS spectrograms of a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet prepared in embodiment 1, wherein (a) XPS full spectrum indicates successful doping of elements N and S; (b) C is fine spectrum indicates the covalent bond structure of elements N and S and element C; (c) N is fine spectrum indicates that element N has the forms of pyrrole nitrogen, pyridine nitrogen, graphite nitrogen and nitrogen oxide; and (d) S 2p fine spectrum indicates the formation, of C-S-C covalent bond. It can be seen from FIG. 2 that elements Ti 2p, C1s, O1s, N1s and S2p exist in the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene.

[0071] As shown in FIG. 3, the illustration represents the color change of solutions in different reaction systems after 10 min. Illustration a is TMB+H.sub.2O.sub.2+NS-Ti.sub.3C.sub.2 system, illustration b is TMB +NS-Ti.sub.3C.sub.2 system, illustration c is TMB+H.sub.2O.sub.2 system, and illustration d is TMB system. It can be seen from FIG. 3 that when H.sub.2O.sub.2 exists, the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet can catalyze H.sub.2O.sub.2 to oxidize colorless TMB into a blue product, and the maximum absorption peak is located at 652 nm. It indicates that the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet of the present invention has peroxidase-like activity.

[0072] FIG. 4 and FIG. 5 show the steady-state kinetic experiments of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet with TMB and H.sub.2O.sub.2 as substrates in embodiment 1. According to Lineweaver-Burk diagram (illustration), Km values of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet, with TMB and H.sub.2O.sub.2 as substrates can be calculated as 0.132 mM and 5.46 mM respectively, indicating that the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has strong affinity for the substrates.

[0073] FIG. 6 shows the absorbance of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet in embodiment 2 after incubation with uric acid of different concentrations. It can be seen from the figure that the absorbance at 652 nm is gradually decreased with the increase of uric acid concentrations. In the range of 5-400 μM, there is a good linear correlation between a colorimetric signal and the uric acid concentration, and a detection limit of uric acid is 1 μM according to a 3-time signal-to-noise ratio method. These results indicate that a uric acid colorimetric sensor based on the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has a wide detection range and a low detection limit.

[0074] FIG. 7 shows the selectivity of the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet for uric acid detection in embodiment 2. Δ.sub.A=-A.sub.1−A.sub.2. A.sub.1 represents the absorbance value of the reaction system after adding TMB, and A.sub.2 represents the absorbance value of the reaction system before adding TMB. The illustrations indicate the influence of different interferents on the color change of the solutions in the reaction system. As shown in FIG. 7, the sensing platform shows excellent selectivity for uric acid.

[0075] The above description of the disclosed embodiments enables those skilled in the art to realize or use the present invention. Many modifications to these embodiments will be apparent to those skilled in the art. The general principle defined herein can be realized in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principle and novel features disclosed herein.