CN110508291B - Au-ZnIn2S4Preparation method of nano array electrode photocatalytic nitrogen fixation material - Google Patents

Abstract

A preparation method of Au-ZnIn ₂ S ₄ nano-array electrode photocatalytic nitrogen fixation material belongs to the preparation and modification method of photoelectrochemical catalytic material. Preparation method: Based on ZnIn ₂ S ₄ nano-array electrode, nano-Au particles are photodeposited on its surface to improve the photocatalytic nitrogen fixation performance of ZnIn ₂ S ₄ ; first, a layer of ZnIn ₂ S ₄ nanosheet array is grown on FTO conductive glass by hydrothermal method , Au-ZnIn ₂ S ₄ electrode was prepared by depositing Au particles on its surface by the method of photodeposition; the Au-ZnIn ₂ S ₄ electrode sheet was fixed and placed in methanol aqueous solution, high-purity nitrogen gas was continuously introduced, and N ₂ is converted into NH ₃ , and then into NH ⁴⁺ ; the reaction solution is mixed with Nessler reagent to develop color, the NH ⁴⁺ concentration in the reaction solution is determined, and then the photocatalytic nitrogen fixation performance of the material is determined. Advantages: simple preparation, loose preparation conditions, non-toxic, easy to recycle in the process of material application, and can be recycled; ZnIn ₂ S ₄ has a narrow band gap and can absorb a wider range of visible light, Au also has strong energy in the visible light range The absorption of visible light improves the comprehensive utilization rate of visible light.

Description

A kind of preparation method of Au-ZnIn2S4 nanometer array electrode photocatalytic nitrogen fixation material

technical field

The invention relates to a method for preparing and modifying a photoelectrochemical catalytic material, in particular to a preparation method for an Au-ZnIn ₂ S ₄ nanometer array electrode photocatalytic nitrogen fixation material.

Background technique

Ammonia is an indispensable raw material for chemical industry, medicine, agriculture, etc. At present, the synthesis of ammonia in industrial production is still the traditional Haber method. The reaction temperature is mostly above 300 °C and the pressure is above 100 atm, and the reaction is carried out in the process of iron-based catalyst catalysis. The _H2 required in the synthesis reaction is mainly produced by the evaporative transformation of natural gas, maintaining the entire reaction process consumes 1-2% of the fossil energy on the earth, and causes a large amount of _CO2 emission. From the perspective of reducing the consumption of non-renewable energy and reducing greenhouse gas emissions, the use of light energy to synthesize ammonia is of great scientific value.

Photoelectric catalysis is the process of converting light energy into chemical energy, which is one of the ideas to solve the energy crisis. There are many materials with photocatalytic properties, but there are very few materials that can achieve photocatalytic nitrogen fixation, mainly because the N ₂ molecule is very stable, and it takes at least 941.69kJ energy per mole of N≡N molecule to fully open, of which 410kJmol is required for the dissociation of the first N-N bond. ^-1 energy, so the energy required to convert nitrogen to ammonia is very large.

_TiO2 photocatalytic material is currently the most studied material, and _TiO2 can improve its photocatalytic nitrogen fixation performance through various modification means. The team of Gong Jinlong of Tianjin University has studied nitrogen fixation on TiO ₂ electrodes, growing a layer of TiO ₂ nanorods on FTO conductive glass by hydrothermal method, and then introducing oxygen vacancies and precious metals into TiO ₂ electrodes to achieve an increase in nitrogen fixation performance to 13.4 nmol /cm ² /h (References: Alammar, T.; Hamm, I.; Grasmik, V.; Wark, M.; Mudring, AV, Microwave-Assisted Synthesis of Perovskite SrSnO3 Nanocrystals in IonicLiquids for Photocatalytic Applications. Inorg Chem 2017 , 56(12), 6920-6932.). There are also many modifications based on _TiO2 materials, and their photocatalytic nitrogen fixation is still not ideal. Constrained by the 3.2eV forbidden band width of the TiO ₂ material itself, the band gap is too wide, and it can only absorb ultraviolet light which accounts for 4% of the energy in sunlight. The photocatalytic performance has been improved to some extent by post-modification, but the low utilization rate of visible light of the matrix TiO ₂ itself is the key to restricting its low photocatalytic nitrogen fixation performance.

The microscopic appearance of nano-ZnIn ₂ S ₄ is sheet-like, with a large photoactive area, and its forbidden band width is around 2.5eV, which can absorb a wide range of visible light and has good photochemical stability. The conduction band position of ZnIn ₂ S ₄ is around -0.74eV, the valence band position is around +1.66eV, and the reduction potential of N ₂ +6H ⁺ +6e ^- →2NH ₃ is -0.15eV under the standard hydrogen electrode test. . Its reduction potential is within the conduction band of ZnIn ₂ S ₄ , and it is theoretically possible to reduce N ₂ to NH ₃ . Deposition of noble metal nanoparticles on semiconductor surfaces by artificial design is a common method to improve the optoelectronic properties of semiconductors. Noble metals absorb light energy to generate hot carriers. When the hot carrier energy is higher than the Schottky barrier at the metal-semiconductor interface, hot electrons are directly injected into the semiconductor conduction band. The invention greatly improves the utilization of visible light through the nano-Au-modified ZnIn ₂ S ₄ , and has a great research space in the fields of optoelectronics and photocatalysis.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of Au-ZnIn ₂ S ₄ nano-array electrode photocatalytic nitrogen fixation material, so as to solve the problem of low photoactive area, low photoelectric performance and low catalytic performance in the current photocatalysis field. The problem.

The technical scheme adopted to achieve the purpose of the present invention: the preparation method of Au-ZnIn ₂ S ₄ nanometer array is as follows: based on _{ZnIn 2} S4 nanometer array electrode, nano Au particles are photodeposited on its surface to improve the photocatalytic nitrogen fixation performance of _{ZnIn 2} S4; firstly A layer of ZnIn ₂ S ₄ nanosheet array was grown on FTO conductive glass by hydrothermal method, and Au particles were deposited on its surface by photodeposition; Au-ZnIn ₂ S ₄ electrode sheet was fixed in methanol aqueous solution, and the High-purity nitrogen, convert N ₂ into NH ₃ under xenon light, and then into NH ⁴⁺ ; Mix the reaction solution with Nessler reagent to develop color, determine the NH ⁴⁺ concentration in the reaction solution, and then determine the photocatalytic nitrogen fixation performance of the material .

The specific steps for the preparation of the Au-ZnIn ₂ S ₄ nanoarrays are as follows:

Step 1. Use zinc nitrate Zn(NO ₃ ) ₂ ·6H ₂ O, indium trichloride InCl ₃ , sulfide urea CH ₄ N ₂ S to prepare a precursor solution in a molar ratio of 1:2:4, and pass through a step of water Thermally prepared FTO conductive glass electrodes with ZnIn ₂ S ₄ nano-layers, namely ZnIn ₂ S ₄ nano-array electrodes;

Step 2. Take 20-60 μL of 50 mmol/L HAuCl ₄ solution and dilute it to 100 mL with pure water, transfer the solution to a quartz electrolytic cell, and fix the ZnIn ₂ S ₄ electrode sheet on the quartz electrolytic cell with a polytetrafluoroethylene electrode clip In the ZnIn 2 S 4 electrode sheet, Au-ZnIn ₂ S ₄ nano-array electrodes were prepared by simulating sunlight irradiation with a xenon lamp to reduce the Au ³⁺ in the solution to Au elemental substance deposited on the ZnIn ₂ S ₄ electrode surface;

Step 3. Test the performance of the photocatalytic nitrogen fixation material of the Au-ZnIn ₂ S ₄ nano-array electrode. The Au-ZnIn ₂ S ₄ electrode was fixed in the methanol aqueous solution, and high-purity nitrogen was continuously introduced, and the air was pre-vented before simulating sunlight exposure. 20min, using simulated sunlight as the energy source, fixing the Au-ZnIn ₂ S ₄ electrode with a platinum sheet electrode clip to form a photocatalytic reaction cell; converting N ₂ into NH ₃ under xenon lamp illumination, and then into NH ⁴⁺ ; The reaction solution is mixed with Nessler reagent to develop color, the concentration of NH ^{4 +} in the reaction solution is determined, and then the photocatalytic nitrogen fixation performance of the material is determined.

In the described step 1, the specific steps for the growth and preparation of ZnIn ₂ S ₄ nanoarrays are as follows:

Step (1-1), cleaning: cut the FTO conductive glass sputtered with SnO ₂ into small pieces of 2×3 cm and number them, and sequentially use pure aqueous solution mixed with glass cleaning agent, pure water, isopropanol, and ethanol 95wt% , ethanol 99wt% ultrasonic for 30min, then air-dry naturally, for use;

Step (1-2), modification: put the cleaned FTO conductive glass in step (1-1) into a 5:1:1 solution of pure water: hydrogen peroxide: ammonia water, let stand for 10 minutes, and take out the tweezers , rinse with plenty of pure water, dry naturally, spare;

Step (1-3), prepare a precursor solution: prepare an aqueous solution with a pH of 1.8 with hydrochloric acid, dissolve 0.75mmol Zn(NO ₃ ) ₂ ·6H ₂ O, 1.50mmol InCl ₃ , 3mmol CH ₄ N ₂ S in 30mL pH = 1.8 in water, magnetic stirring for 20min to completely dissolve the drug to obtain a precursor solution;

Step (1-4), the conductive surface of the modified FTO conductive glass is tilted downward and put into the 50ml hydrothermal reactor lining, and the precursor solution in step (1-3) is transferred to the reactor;

In step (1-5), the reaction kettle is sealed, placed in an oven, kept at 180° C. for 3 hours, and cooled to room temperature naturally to obtain a light yellow film uniformly covered on the conductive surface of the FTO conductive glass, and the light yellow film is ZnIn ₂ S ₄ Nano film; FTO conductive glass was rinsed with slow water and vacuum dried for 6h to obtain ZnIn ₂ S ₄ nanometer array electrodes.

In the step 2, gold is deposited on the surface of the ZnIn ₂ S ₄ nanoarray electrode; the specific steps are as follows:

In step (2-1), 40 μl of 50 mmol/L AuHCl ₄ was diluted to 100 mL with pure water to obtain a solution containing 0.394 mg of Au, and the solution was transferred into a quartz electrolytic cell;

In step (2-2), the ZnIn ₂ S ₄ electrode was fixed with a polytetrafluoroethylene electrode clip, and all of it was immersed in the solution in step (2-1), and the surface with the ZnIn ₂ S ₄ nano-film was facing the xenon lamp light source, and the magnetic stirring was carried out. The ZnIn ₂ S ₄ electrode was subjected to photodeposition under medium illumination for 30 min;

In step (2-3), the photodeposited electrode was rinsed three times with deionized water, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn ₂ S ₄ nanoarray electrode with Au deposited on the surface.

In the step 2, the illumination intensity of the simulated sunlight is 100 mW/cm ² , and the illumination is performed at room temperature for 20-40 minutes.

In the step 3, the flow rate of the high-purity nitrogen N2 introduced is 20 ml/min, and the ventilation is preliminarily ventilated for 20 minutes before simulating sunlight irradiation; in the methanol aqueous solution, the volume ratio of 99% methanol to water is 1:4.

Special equipment for photodepositing gold particles on the surface of ZnIn ₂ S ₄ nanoarrays: including xenon lamp to simulate sunlight, electrode clips, ZnIn ₂ S ₄ nanoarray electrodes, magnetic stirrer, magneton and electrochemical reaction cell; installed on the magnetic stirrer Electrochemical reaction cell, there are magnetons in the electrochemical reaction cell, electrode clips at the upper end of the electrochemical reaction cell, electrode clips clamp ZnIn ₂ S ₄ nano-array electrodes, and a xenon lamp simulates sunlight to illuminate ZnIn ₂ outside the electrochemical reaction cell S4 _nanoarray electrode ₃ , _ZnIn2S4 nanoarray electrode is placed in the electrolyte.

Beneficial effects, due to the adoption of the above scheme, a one-step hydrothermal method is used to grow _{ZnIn 2} ^S ₄ nanometer arrays _on FTO conductive glass _; ⁺ is reduced to produce gold particles, irradiated for 30 min under stirring conditions, washed and dried to obtain a ZnIn ₂ S ₄ nanoarray electrode with nano Au particles deposited on the surface.

The Au-ZnIn ₂ S ₄ electrode sheet was prepared by the method of photodeposition, and the Au-ZnIn ₂ S ₄ electrode sheet was used in the field of photocatalytic nitrogen fixation to develop a new photocatalytic nitrogen fixation material. The deposition of Au particles is beneficial to improve the absorption of light by _{ZnIn 2} S ₄ , and the photodeposition method is beneficial to the selective deposition of Au on the highly active surface _. The high optoelectronic properties further promote the photoreduction deposition of Au particles on the edges of ZnIn ₂ S ₄ sheets. The deposition of Au particles is beneficial to improve the absorption of light by ZnIn ₂ S ₄ , and the photoelectrons absorbed by the Au particles at the edge are transferred to ZnIn ₂ S ₄ , which in turn promotes the activation of N ₂ adsorbed on ZnIn ₂ S ₄ , and realizes photocatalytic nitrogen fixation.

Gold particles are deposited on the surface of _{ZnIn 2} S ₄ nanoarrays. The surface plasmon effect of gold can effectively improve the light absorption of ZnIn ₂ S ₄ in the visible light region _. The ability of the array to photoreduce _N2 to produce _NH3 . Experiments show that the absorption of visible light by the ZnIn ₂ S ₄ nanoarrays of gold nanoparticles by simple photodeposition is obviously improved, and the optoelectronic properties are also improved. At the same time, this material is an array material, which can be easily recycled and reused. The preparation and processing process is non-toxic and relatively simple, and has great potential in photocatalytic nitrogen fixation.

The problems of low photoactive area, low photoelectric performance and low catalytic performance in the current photocatalysis field are solved, and the purpose of the present invention is achieved.

The present invention has the following advantages:

1. The material has the advantages of simple preparation, loose preparation conditions, non-toxicity, easy recovery in the process of material application, and can be recycled.

2. With the narrow band gap of ZnIn ₂ S ₄ , it can absorb a wider range of visible light, and Au can also have a strong absorption in the visible light range, thereby improving the comprehensive utilization rate of the material for visible light.

Description of drawings

FIG. 1 is a schematic structural diagram of an apparatus for optically depositing gold particles on the surface of a ZnIn ₂ S ₄ nanoarray according to the present invention.

FIG. 2 is a typical XRD pattern of ZnIn ₂ S ₄ nanoarrays grown on FTO conductive glass in Example 1 of the present invention.

Figure 3-a is a typical scanning electron microscope topography of the ZnIn ₂ S ₄ nanoarrays grown on FTO conductive glass in Example 1 of the present invention.

FIG. 3-b is a scanning electron microscope image of surface photodeposited gold of ZnIn ₂ S ₄ nanoarrays grown on FTO conductive glass in Example 2 of the present invention.

3-c is a large-scale scanning electron microscope image of the surface photodeposited gold of ZnIn ₂ S ₄ nanoarrays grown on FTO conductive glass in Example 2 of the present invention.

FIG. 4 is the UV-Vis diffuse reflection absorption spectrum after growing ZnIn ₂ S ₄ nanoarrays on FTO conductive glass and photodepositing Au of different qualities according to the present invention.

FIG. 5 is the corresponding characteristic diagram of photocurrent under visible light irradiation after growing ZnIn ₂ S ₄ nanoarrays on FTO conductive glass and photodepositing Au of different qualities according to the present invention.

FIG. 6 is a Nyquist diagram of AC impedance under visible light irradiation after growing ZnIn ₂ S ₄ nanoarrays on FTO conductive glass and photodepositing Au of different qualities according to the present invention.

FIG. 7 is a graph showing the photocatalytic nitrogen fixation performance after growing ZnIn ₂ S ₄ nanoarrays on FTO conductive glass and photo-depositing Au of different qualities according to the present invention.

In Fig. 1, 1. Xenon lamp simulates sunlight; 2. Electrode clip; 3. ZnIn ₂ S ₄ nanoarray electrode; 4. Magnetic stirrer; 5. Magneton; 6. Electrochemical reaction cell.

Detailed ways

The preparation method of Au-ZnIn ₂ S ₄ nanoarray is as follows: based on ZnIn ₂ S ₄ nano-array electrode, nano-Au particles are photodeposited on its surface to improve the photocatalytic nitrogen fixation performance of ZnIn ₂ S ₄ ; firstly, the hydrothermal method is used on FTO conductive glass. A layer of ZnIn ₂ S ₄ nanosheet array was grown, and Au particles were deposited on its surface by photodeposition; the Au-ZnIn ₂ S ₄ electrode sheet was fixed and placed in methanol aqueous solution, and high-purity nitrogen gas was continuously passed in, and under the illumination of xenon lamp, the N ₂ is converted into NH ₃ , and then into NH ⁴⁺ ; the reaction solution is mixed with Nessler reagent for color development, the NH ⁴⁺ concentration in the reaction solution is determined, and the photocatalytic nitrogen fixation performance of the material is determined.

The specific steps for the preparation of the Au-ZnIn ₂ S ₄ nanoarrays are as follows:

Step 1. Use zinc nitrate Zn(NO ₃ ) ₂ ·6H ₂ O, indium trichloride InCl ₃ , sulfide urea CH ₄ N ₂ S to prepare a precursor solution in a molar ratio of 1:2:4, and pass through a step of water FTO conductive glass electrodes with ZnIn ₂ S ₄ nano-layers, namely ZnIn ₂ S ₄ electrode sheets, are prepared by thermal method;

Step 2. Take 20-60 μL of 50 mmol/L HAuCl ₄ solution and dilute it to 100 mL with pure water, transfer the solution to a quartz electrolytic cell, and fix the ZnIn ₂ S ₄ electrode sheet on the quartz electrolytic cell with a polytetrafluoroethylene electrode clip In the ZnIn 2 S 4 electrode sheet, Au-ZnIn ₂ S ₄ nano-array electrodes were prepared by simulating sunlight irradiation with a xenon lamp to reduce the Au ³⁺ in the solution to Au elemental substance deposited on the ZnIn ₂ S ₄ electrode surface;

Step 3. The Au-ZnIn ₂ S ₄ nanoarray electrode is fixed and placed in an aqueous methanol solution, and high-purity nitrogen gas is continuously introduced to convert N ₂ into NH ₃ and then into NH ⁴⁺ under the illumination of xenon lamp; The NH ⁴⁺ concentration in the reaction solution was determined by mixing and developing the color of the reaction solution, and then the photocatalytic nitrogen fixation performance of the material was determined.

In the described step 1, the specific steps for the growth and preparation of ZnIn ₂ S ₄ nanoarrays are as follows:

Step (1-1), cleaning: cut the FTO conductive glass sputtered with SnO ₂ into small pieces of 2×3 cm and number them, and sequentially use pure aqueous solution mixed with glass cleaning agent, pure water, isopropanol, and ethanol 95wt% , ethanol 99wt% ultrasonic for 30min, then air-dry naturally, for use;

Step (1-2), modification: put the cleaned FTO conductive glass in step (1-1) into a 5:1:1 solution of pure water: hydrogen peroxide: ammonia water, let stand for 10 minutes, and take out the tweezers , rinse with plenty of pure water, dry naturally, spare;

Step (1-3), prepare a precursor solution: prepare an aqueous solution with a pH of 1.8 with hydrochloric acid, dissolve 0.75mmol Zn(NO ₃ ) ₂ ·6H ₂ O, 1.50mmol InCl ₃ , 3mmol CH ₄ N ₂ S in 30mL pH = 1.8 in water, magnetic stirring for 20min to completely dissolve the drug to obtain a precursor solution;

Step (1-4), the conductive surface of the modified FTO conductive glass is tilted downward and put into the 50ml hydrothermal reactor lining, and the precursor solution in step (1-3) is transferred to the reactor;

In step (1-5), the reaction kettle is sealed, placed in an oven, kept at 180° C. for 3 hours, and cooled to room temperature naturally to obtain a light yellow film uniformly covered on the conductive surface of the FTO conductive glass, and the light yellow film is ZnIn ₂ S ₄ Nano film; FTO conductive glass was rinsed with slow water and vacuum dried for 6h to obtain ZnIn ₂ S ₄ nanometer array electrodes.

In the step 2, gold is deposited on the surface of the ZnIn ₂ S ₄ nanoarray electrode; the specific steps are as follows:

In step (2-1), 40 μl of 50 mmol/L AuHCl ₄ was diluted to 100 mL with pure water to obtain a solution containing 0.394 mg of Au, and the solution was transferred into a quartz electrolytic cell;

In step (2-2), the ZnIn ₂ S ₄ electrode was fixed with a polytetrafluoroethylene electrode clip, and all of it was immersed in the solution in step (2-1), and the surface with the ZnIn ₂ S ₄ nano-film was facing the xenon lamp light source, and the magnetic stirring was carried out. The ZnIn ₂ S ₄ nano-array electrode was subjected to photodeposition under medium illumination for 30 min;

In step (2-3), the photo-deposited electrode was rinsed three times with deionized water, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn ₂ S ₄ electrode sheet with Au deposited on the surface;

In the step 2, the illumination intensity of the simulated sunlight is 100 mW/cm ² , and the illumination is performed at room temperature for 20-40 minutes.

A special device for photo-depositing gold particles on the surface of ZnIn ₂ S ₄ nano-array: including xenon lamp simulating sunlight 1, electrode clip 2, ZnIn ₂ S ₄ nano-array electrode 3, magnetic stirrer 4, magneton 5 and electrochemical reaction cell 6;

An electrochemical reaction cell 6 is arranged on the magnetic stirrer 4, and there is a magnet 5 in the electrochemical reaction cell 6, and an electrode clip 2 is arranged on the upper end of the electrochemical reaction cell 6, and the electrode clip 2 clamps the ZnIn ₂ S ₄ nanometer array electrode 3 , outside the electrochemical reaction cell 6, a xenon lamp simulates sunlight 1 to illuminate the ZnIn ₂ S ₄ nanometer array electrode ₃ , and the ZnIn ₂ S4 nanometer array electrode 3 is placed in the electrolyte.

The present invention will be further described in detail with reference to the experimental specific embodiments of the accompanying drawings.

1. The present invention adopts a one-step hydrothermal method to prepare ZnIn ₂ S ₄ nanometer array, and improves its photoelectrochemical performance by surface photodeposition of nanometer Au particles, and at the same time improves its photocatalytic nitrogen fixation ability.

2. Various experimental drugs in the following examples are all analytically pure.

3. The ZnIn ₂ S ₄ nanoarray is a single crystal structure, hexagonal phase crystal type, and the thickness is about 100nm.

4. To prepare ZnIn ₂ S ₄ nanoarrays, the specific steps are as follows:

(4-1). Cut the FTO glass sputtered with SnO ₂ into small pieces of 2 × 3 cm and number them on the non-conductive surface. Then use pure aqueous solution mixed with glass cleaning agent, pure water, isopropanol, and ethanol 95wt% , ethanol 99wt% ultrasonic for 30min. After drying naturally, spare;

(4-2). Put the glass in (4-1) into a 5:1:1 solution of V _{pure water} : V _{hydrogen peroxide} : V _{ammonia water} , let it stand for 10 minutes, take it out with tweezers, rinse with plenty of pure water, Natural dry, spare;

(4-3). Weigh 0.2231g Zn(NO ₃ ) ₂ ·6H ₂ O, 0.2284g CH ₄ N ₂ S, 0.3318g InCl ₃ into a 50mL beaker with an analytical balance, add 30mL pH=1.8 aqueous hydrochloric acid solution to it, The drug is completely dissolved under the action of magnetic stirring;

(4-4). The conductive surface of the modified FTO conductive glass is tilted downward and put into the lining of the 50ml hydrothermal reactor, and the solution in 4-3) is transferred to the lining;

(4-5). The reaction kettle was sealed, placed in an oven, kept at 180°C for 3 hours, and cooled to room temperature naturally to obtain a light yellow film evenly covered on the conductive surface of the FTO. After the FTO was rinsed with slow water and vacuum dried, ZnIn ₂ was obtained. S ₄ nanometer array electrodes.

Example 1: Deposition of 0.2 mg Au on the surface of ZnIn ₂ S ₄ nanoarrays.

1. Dissolve 20 μl of 50 mmol/L AuHCl ₄ in 100 mL of pure water to obtain a solution containing 0.2 mg of Au, and transfer the solution into a quartz electrolytic cell.

2. Fix the electrode sheet with a polytetrafluoroethylene electrode clip, immerse the whole in the medium solution, face the xenon lamp light source on the side with the ZnIn ₂ S ₄ nano-film, and illuminate for 30 minutes in the magnetic stirring.

3. The electrode sheet was taken out, slowly rinsed with pure water for 3 min, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn2S4 electrode sheet with 0.2 mg of Au photo-deposited.

Example 2: Deposition of 0.4 mg Au on the surface of ZnIn ₂ S ₄ nanoarrays.

1. Dissolve 40 μl of 50 mmol/L AuHCl ₄ in 100 mL of pure water to obtain a solution containing 0.4 mg of Au, and transfer the solution into a quartz electrolytic cell.

2. Fix the electrode sheet with a polytetrafluoroethylene electrode clip, immerse the whole in the medium solution, face the xenon lamp light source on the side with the ZnIn ₂ S ₄ nano-film, and illuminate for 30 minutes in the magnetic stirring.

3. The electrode sheet was taken out, slowly rinsed with pure water for 3 min, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn ₂ S ₄ electrode sheet with 0.4 mg of Au photo-deposited.

Example 3: Deposition of 0.6 mg Au on the surface of ZnIn ₂ S ₄ nanoarrays.

1. Dissolve 60 μl of 50 mmol/L AuHCl ₄ in 100 mL of pure water to obtain a solution containing 0.6 mg of Au, and transfer the solution into a quartz electrolytic cell.

2. Fix the electrode sheet with a polytetrafluoroethylene electrode clip, immerse it all in the solution, face the xenon light source on the side with the ZnIn ₂ S ₄ nano-film, and illuminate for 30 min in magnetic stirring.

3. The electrode sheet was taken out, slowly rinsed with pure water for 3 min, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn ₂ S ₄ electrode sheet with photodeposited 0.6 mg Au.

Example 4: Photoelectrochemical performance test of ZnIn ₂ S ₄ electrode sheet and Au-ZnIn ₂ S ₄ electrode sheet.

1. Equipped with 150mL 0.1mol/L Na ₂ SO ₄ solution, fix the electrode piece with a platinum piece electrode clip, the platinum piece electrode is the counter electrode, and the Hg/HgCl saturated potassium chloride electrode is the reference electrode to form a three-electrode system. The photoelectrochemical properties of the electrode sheets were tested by an electrochemical workstation.

2. In Figure 5, the applied bias voltage is 0V to test the photocurrent response characteristics of different electrode sheets.

3. In Figure 6, 0.2V bias is applied when testing the AC impedance of different electrode sheets under illumination conditions, the high frequency is 50000Hz, and the low frequency is 0.1Hz.

Example 5: Photocatalytic nitrogen fixation performance test of ZnIn ₂ S ₄ electrode sheet and Au-ZnIn ₂ S ₄ electrode sheet.

1. Configure 30mL methanol aqueous solution (V _{methanol 95wt%} : V _{pure water} =1:4), fix the electrode sheet with platinum electrode clips, place it in a special reactor, and pass high-purity nitrogen gas into it from the bottom of the reactor, The ventilation rate was 20 mL/min.

2. Irradiate the ZnIn ₂ S ₄ electrode sheet in the reactor with a 300W xenon lamp light source, and collect 2 mL of the reaction solution every 25 min.

3. Mix 1 mL of the collection solution with 1 mL of Nessler's solution, react in the dark for 10 min, transfer it into a 2 mL cuvette, and test the absorbance of the reaction solution with a UV-Vis spectrophotometer at 420 nm.

4. Test the absorbance of the reaction solution Find the corresponding ammonia concentration in the standard ammonia solution absorbance curve, perform unit conversion, and compare the photoelectric nitrogen fixation of ZnIn ₂ S ₄ nanoarrays before and after gold loading, as shown in Figure 7.

Claims (2)

1. a preparation method of Au-ZnIn ₂ S ₄ nanometer array electrode photocatalytic nitrogen-fixing material, it is characterized in that: the preparation method of Au-ZnIn ₂ S ₄ nanometer array is: based on ZnIn ₂ S ₄ nanometer array electrode photodeposition on its surface Nano Au particles can improve the photocatalytic nitrogen fixation performance of ZnIn ₂ S ₄ ; first, a layer of ZnIn ₂ S ₄ nanosheet arrays are grown on FTO conductive glass by hydrothermal method, and Au particles are deposited on the surface by photodeposition; Au- The ZnIn ₂ S ₄ electrode sheet was fixed into methanol aqueous solution, and high-purity nitrogen gas was continuously introduced into it. Under the illumination of xenon lamp, N ₂ was converted into NH ₃ , and then into NH ₄ ⁺ ; the reaction solution was mixed with Nessler reagent to develop color, Determine the concentration of NH ₄ ⁺ in the reaction solution, and then determine the photocatalytic nitrogen fixation performance of the material; The preparation method of the described Au-ZnIn ₂ S ₄ nanometer array, the specific steps are as follows: Step 1. Use zinc nitrate Zn(NO ₃ ) ₂ ·6H ₂ O, indium trichloride InCl ₃ , sulfide urea CH ₄ N ₂ S to prepare a precursor solution in a molar ratio of 1:2:4, and pass through a step of water Thermally prepared FTO conductive glass electrodes with ZnIn ₂ S ₄ nano-layers, namely ZnIn ₂ S ₄ nano-array electrodes; Step 2. Take 20-60 μL of 50 mmol/L HAuCl ₄ solution and dilute it to 100 mL with pure water, transfer the solution to a quartz electrolytic cell, and fix the ZnIn ₂ S ₄ electrode sheet on the quartz electrolytic cell with a polytetrafluoroethylene electrode clip In the ZnIn ₂ S ₄ electrode sheet, Au-ZnIn ₂ S ₄ nano-array electrodes were prepared by simulating sunlight irradiation with a xenon lamp to reduce the Au ³⁺ in the solution to Au element; Step 3. Test the performance of Au-ZnIn ₂ S ₄ nano-array electrode photocatalytic nitrogen fixation material. The Au-ZnIn ₂ S ₄ electrode sheet is fixed in methanol aqueous solution, and high-purity nitrogen gas is continuously injected. Ventilation for 20min, using simulated sunlight as the energy source, fixing the Au-ZnIn ₂ S ₄ nano-array electrode with platinum sheet electrode clips to form a photocatalytic reaction cell; under the illumination of xenon lamp, N ₂ was converted into NH ₃ , and then into NH ₄ ⁺ ; get the reaction solution mixed with Nessler reagent to develop color, determine the NH ₄ ⁺ concentration in the reaction solution, and then determine the photocatalytic nitrogen fixation performance of the material; In the step 2, the illumination intensity of the simulated sunlight is 100mW/cm ² , and the illumination is irradiated at room temperature for 20-40min; In the described step 3, the flow rate of the high-purity nitrogen N ₂ introduced was 20 mL/min, and the ventilation was performed for 20 min before the simulated sunlight irradiation; in the methanol aqueous solution, the volume ratio of 99wt% methanol to water was 1:4 ; In the described step 1, the specific steps for the growth and preparation of ZnIn ₂ S ₄ nanoarrays are as follows: Step (1-1), cleaning: cut the FTO conductive glass sputtered with SnO ₂ into small pieces of 2×3 cm and number them, and sequentially use pure aqueous solution mixed with glass cleaning agent, pure water, isopropanol, and ethanol 95wt% , ethanol 99wt% ultrasonic for 30min, then air-dry naturally, for use; Step (1-2), modification: put the cleaned FTO conductive glass in step (1-1) into a 5:1:1 solution of pure water: hydrogen peroxide: ammonia water, let stand for 10 minutes, and take out the tweezers , rinse with plenty of pure water, dry naturally, spare; Step (1-3), prepare a precursor solution: prepare an aqueous solution with a pH of 1.8 with hydrochloric acid, dissolve 0.75 mmol Zn(NO ₃ ) ₂ ·6H ₂ O, 1.50 mmol InCl ₃ and 3 mmol CH ₄ N ₂ S in 30 mL of pH=1.8 In water, magnetic stirring for 20min completely dissolves the drug to obtain the precursor solution; In step (1-4), the conductive surface of the modified FTO conductive glass is tilted downward and placed into the lining of a 50mL hydrothermal reactor, and the precursor solution in step (1-3) is transferred to the reactor; In step (1-5), the reaction kettle is sealed, placed in an oven, kept at 180° C. for 3 hours, and cooled to room temperature naturally, to obtain a light yellow film evenly covered on the conductive surface of the FTO conductive glass, and the light yellow film is ZnIn ₂ S ₄ Nano film; FTO conductive glass was rinsed with slow water and vacuum dried for 6h to obtain ZnIn ₂ S ₄ nanoarray electrodes; In the described step 2, gold is deposited on the surface of the ZnIn ₂ S ₄ nanoarray; the specific steps are as follows: Step (2-1), dilute 20-60 μL 50mmol/L of _HAuCl to 100 mL with pure water, and transfer the solution into a quartz electrolytic cell; In step (2-2), the ZnIn ₂ S ₄ electrode was fixed with a polytetrafluoroethylene electrode clip, and all of it was immersed in the solution in step (2-1), and the surface with the ZnIn ₂ S ₄ nano-film was facing the xenon lamp light source, and the magnetic stirring was carried out. The ZnIn ₂ S ₄ electrode is subjected to photodeposition under medium illumination for 20-40min; In step (2-3), the photodeposited electrode was rinsed three times with deionized water, and vacuum-dried at 60° C. for 6 h to obtain an Au-ZnIn ₂ S ₄ nanoarray electrode with Au deposited on the surface. 2. the special device of the preparation method of a kind of Au-ZnIn ₂ S ₄ nanometer array electrode photocatalytic nitrogen-fixing material according to claim 1, it is characterized in that: the special device of photo-depositing gold particles on the ZnIn ₂ S ₄ nanometer array surface: Including xenon lamp to simulate sunlight, electrode clips, ZnIn ₂ S ₄ nano-array electrodes, magnetic stirrer, magneton and electrochemical reaction cell; the electrochemical reaction cell is arranged on the magnetic stirrer, and there is a magneton in the electrochemical reaction cell, and there are magnetons in the electrochemical reaction cell. There is an electrode clip on the upper end of the electrochemical reaction cell, and the electrode clip clamps the ZnIn ₂ S ₄ nanometer array electrode. Outside the electrochemical reaction cell, a xenon lamp simulates sunlight to illuminate the _{ZnIn 2} S ₄ nanometer array electrode _. in the electrolyte.

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