阅读说明：本技术 一种NiS/CuInS2/BiOCl电极及其制备方法 (NiS/CuInS2/BiOCl electrode and preparation method thereof ) 是由 董玉明 张煜霞 李激 张萍波 冷炎 王光丽 顾丹 朱永法 蒋平平 于 2020-12-01 设计创作，主要内容包括：本发明公开了一种NiS/CuInS_2/BiOCl电极及其制备方法,属于材料科学技术和化学领域。本发明所述的制备NiS/CuInS_2/BiOCl电极的方法,包括如下步骤：在反应容器中将CuInS_2/BiOCl电极固定,之后在反应容器中加入硫脲、醋酸镍和乙醇的混合水溶液,氮气脱气；脱气完成之后,置于氙灯下光照；光照之后洗涤、干燥,得到NiS/CuInS_2/BiOCl电极。本发明的NiS/CuInS_2/BiOCl电极的光催化活性高,可以用于光催化分解水产氢反应,反应1h后其产氢速率达到0.048μmol/h以上。(The invention discloses a NiS/CuInS 2 A/BiOCl electrode and a preparation method thereof belong to the field of material science and technology and chemistry. The preparation method of NiS/CuInS 2 A method of manufacturing a/BiOCl electrode, comprising the steps of: in a reaction vessel, adding CuInS 2 Fixing a/BiOCl electrode, adding a mixed aqueous solution of thiourea, nickel acetate and ethanol into a reaction container, and degassing by nitrogen; after degassing is finished, placing the mixture under a xenon lamp for illumination; washing and drying after illumination to obtain NiS/CuInS 2 a/BiOCl electrode. NiS/CuInS of the invention 2 the/BiOCl electrode has high photocatalytic activity, can be used for the reaction of decomposing water into hydrogen by photocatalysis, and the hydrogen production rate of the/BiOCl electrode reaches over 0.048 mu mol/h after the reaction is carried out for 1 h.)

1. Preparation of NiS/CuInS₂The method for the BiOCl electrode is characterized by comprising the following steps:

in a reaction vessel, adding CuInS₂Fixing a/BiOCl electrode, adding a mixed aqueous solution of thiourea, nickel acetate and ethanol into a reaction container, and degassing by nitrogen; after degassing is finished, placing the mixture under a xenon lamp for illumination; washing and drying after illumination to obtain NiS/CuInS₂a/BiOCl electrode.

2. The method of claim 1, wherein said CuInS is present₂the/BiOCl electrode is CuInS after calcination₂a/BiOCl electrode; in particular to CuInS₂the/BiOCl electrode is calcined for 20-40min at the temperature of 350-450 ℃ in Ar atmosphere.

3. The method of claim 1 or 2, wherein the CuInS is present₂The preparation method of the/BiOCl electrode comprises the following steps:

(1) sequentially immersing the BiOCl electrode into CuCl₂、Na₂S、InCl₃、Na₂Each time of the adsorption solution of S is 1-2min, the electrode is taken out and washed each time, and then is immersed into the next adsorption solution, and the operation marks are a cycle; the CuInS is prepared by controlling the cycle number to be 1-4 and drying after the adsorption is finished₂a/BiOCl electrode sample; wherein CuCl₂The concentration of the solution is 4-6mM, Na₂The concentration of S solution is 45-55mM, InCl₃The concentration of the solution is 4-6 mM;

(2) drying the CuInS₂Calcining the/BiOCl electrode sample in a tubular furnace with Ar atmosphere at the temperature of 350-450 ℃ for 20-40min to obtain CuInS₂a/BiOCl electrode.

4. According toThe method of claim 3, wherein said CuInS₂The BiOCl electrode is synthesized by a solvothermal method in the preparation method of the/BiOCl electrode.

5. The method according to any one of claims 1 to 4, wherein the concentration of thiourea in the mixed aqueous solution of thiourea, nickel acetate and ethanol is 30 to 40mM, the concentration of nickel acetate is 4 to 6mM, and the volume ratio of ethanol to water is 1: 4-6.

6. A method according to any one of claims 1 to 5, wherein the nitrogen is degassed for a period of 30 to 40 min.

7. The method according to any one of claims 1 to 6, wherein the xenon lamp exposure is in particular at 300W for 5min to 25 min.

8. A method according to any one of claims 1 to 7, wherein the washing is 2 to 5 times with water.

9. NiS/CuInS prepared by the method of any one of claims 1 to 8₂a/BiOCl electrode.

10. The NiS/CuInS of claim 9₂The application of the/BiOCl electrode in catalytic hydrogen production.

Technical Field

The invention relates to a NiS/CuInS₂A/BiOCl electrode and a preparation method thereof belong to the field of material science and technology and chemistry.

Background

Solar energy converts water into clean fuel (H)₂) Is one of the important strategies and Photoelectrochemical (PEC) water splitting is an ideal method. The photoelectric series system consists of a photoelectric cathode, a photoelectric anode and an electrolytic cell, and water molecules are subjected to reduction and oxidation reactions on the electrodes. Electrons and holes are photo-excited in the bandgap of the semiconductor photocatalyst and transferred to surface active sites, which are then consumed by surface redox reactions. In many cases, recombination is the main process that photoexcited carriers undergo. In order to promote charge separation and increase surface reaction, a proper hole conduction layer is required to be additionally arranged in the electrode structure to transfer holes in time so as to inhibit the recombination of photo-generated electron-hole pairs, thereby improving the performance of the photocathode. For example, the photo-generated holes may be consumed by the valence band transfer of NiO to external circuitry. However, NiO is only suitable for a portion of photocathodes according to the energy level matching requirement, because the types of light-absorbing materials are very abundant, and the development of hole-conducting layer materials is relatively slow. Many semiconductor materials are not suitable as hole conducting layers, nor do they provide a hole transport channel for the photoactive material, since they do not perfectly match the energy level of the photocatalytic material. In addition, good stability, high mass transfer efficiency, simple and convenient preparation method and the like are all the precondition for the existence of the hole conduction layer, which leads to the scarcity of the hole conduction layer. Therefore, the development of a novel hole conducting layer is of great significance for the development of a novel photocathode.

BiOCl is a stable p-type semiconductor material, has a band gap of about 3.4-3.8eV, can effectively absorb ultraviolet light, and has a good application prospect in the aspects of photocatalytic degradation of harmful pollutants and hydrogen production by water photolysis. BiOCl also has significant water splitting potential from PEC, but its wide band gap inhibits absorption of visible light.

Therefore, the development of BiOCl as a potential hole-conducting layer material is very promising.

Disclosure of Invention

In order to solve at least one of the problems described above, the present invention provides a NiS/CuInS₂The invention relates to a/BiOCl electrode and a preparation method thereof, and CuInS in the electrode₂The valence band is close to the position of the conduction band of BiOCl, which is beneficial to timely leading CuInS₂The internal holes are transferred to the conduction band of BiOCl. And CuInS₂Can almost absorb light in the full spectrum, and has excellent light absorption performance. In addition, the invention adopts a mild photochemical deposition method in CuInS₂NiS is deposited on the surface as a cocatalyst, and NiS/CuInS is used for simulating the sunlight condition₂The density of photocurrent generated by the/BiOCl photocathode is about-1.2 mA-cm^-2(0V vs.RHE)。

The first purpose of the invention is to provide a method for preparing NiS/CuInS₂A method of manufacturing a/BiOCl electrode, comprising the steps of:

in a reaction vessel, adding CuInS₂Fixing a/BiOCl electrode, adding a mixed aqueous solution of thiourea, nickel acetate and ethanol into a reaction container, and degassing by nitrogen; after degassing is finished, placing the mixture under a xenon lamp for illumination; washing and drying after illumination to obtain NiS/CuInS₂a/BiOCl electrode.

In one embodiment of the present invention, the CuInS is₂the/BiOCl electrode is CuInS after calcination₂a/BiOCl electrode; in particular to CuInS₂Calcining the/BiOCl electrode in Ar atmosphere at 350-450 ℃ for 20-40 min; more preferably: mixing CuInS₂the/BiOCl electrode is calcined for 30min at 400 ℃ in Ar atmosphere.

In one embodiment of the present invention, the CuInS is₂The preparation method of the/BiOCl electrode comprises the following steps:

(1) sequentially immersing the BiOCl electrode into CuCl₂、Na₂S、InCl₃、Na₂In adsorption solution of SEach time for 1-2min, taking out the electrode each time, washing, and then immersing into the next adsorption solution, wherein the operation marks are a cycle; the CuInS is prepared by controlling the cycle number to be 1-4 and drying after the adsorption is finished₂a/BiOCl electrode sample; wherein CuCl₂The concentration of the solution is 4-6mM, Na₂The concentration of S solution is 45-55mM, InCl₃The concentration of the solution is 4-6 mM;

(2) drying the CuInS₂Calcining the/BiOCl electrode sample in a tubular furnace with Ar atmosphere at the temperature of 350-450 ℃ for 20-40min to obtain CuInS₂a/BiOCl electrode.

In one embodiment of the present invention, the CuInS is₂CuCl in preparation method of/BiOCl electrode₂The concentration of the solution was 5mM, Na₂The concentration of the S solution was 50mM, InCl₃The concentration of the solution was 5 mM.

In one embodiment of the present invention, the CuInS is₂In the preparation method of the/BiOCl electrode, dried CuInS is used₂the/BiOCl electrode is calcined in a tube furnace with Ar atmosphere at 400 ℃ for 30 min.

In one embodiment of the present invention, the CuInS is₂In the preparation method of the/BiOCl electrode, the BiOCl electrode is synthesized by a solvothermal method, and the preparation method comprises the following specific steps:

taking 10mmol of Bi (NO)₃)·5H₂O in 20.0mL Ethylene Glycol (EG), while 10mmol NaCl in 20.0mL methanol; mixing and stirring the two solutions for 2 hours to obtain a transparent solution; placing FTO conductive glass in the solution to form a certain angle with the inner wall of the 80.0mL Teflon substrate, wherein the conductive surface faces downwards; after reacting for 8h at 180 ℃, taking out the electrode, washing the electrode for 2-3 times by water, and drying the electrode in ambient air; then calcining the electrode in Ar atmosphere in a tube furnace at 350 ℃ for 2 hours; thus obtaining the BiOCl electrode.

In one embodiment of the invention, the concentration of thiourea in the mixed aqueous solution of thiourea, nickel acetate and ethanol is 30-40mM, the concentration of nickel acetate is 4-6mM, and the volume ratio of ethanol to water is 1: 4-6, more preferably: the concentration of thiourea is 35mM, the concentration of nickel acetate is 5mM, and the volume ratio of ethanol to water is 1: 5.

in one embodiment of the present invention, the ethanol is absolute ethanol.

In one embodiment of the present invention, the time for degassing the nitrogen is 30-40 min.

In one embodiment of the invention, the xenon lamp is placed under a 300W xenon lamp for illumination for 5min to 25 min.

In one embodiment of the invention, the washing is 2-5 times with water.

The second purpose of the invention is to prepare the NiS/CuInS prepared by the method of the invention₂a/BiOCl electrode.

The third purpose of the invention is to provide the NiS/CuInS₂The application of the/BiOCl electrode in catalytic hydrogen production.

The invention has the beneficial effects that:

(1) the invention relates to NiS/CuInS₂the/BiOCl electrode is prepared by adopting cheap raw materials and a simple method under the room temperature condition, and essentially, under the illumination condition, the metal is anchored and loaded on a light absorption carrier in a sulfide form.

(2) The invention is in CuInS₂The process of depositing the transition metal sulfide on the surface of the/BiOCl electrode is mild and controllable, and the previous electrode layer can be kept from being damaged.

(3) NiS/CuInS of the invention₂the/BiOCl electrode has high photocatalytic activity, can be used for the reaction of decomposing water into hydrogen by photocatalysis, and the hydrogen production rate of the/BiOCl electrode reaches over 0.048 mu mol/h after the reaction is carried out for 1 h.

Drawings

FIG. 1 is the NiS/CuInS of example 1₂XRD pattern of/BiOCl electrode.

FIG. 2 is the NiS/CuInS of example 1₂XPS spectra of/BiOCl electrodes; wherein (a) NiS/CuInS₂XPS full scan spectrum of/BiOCl photocathode; (b) high resolution XPS spectra of Bi 4f, (c) O1S, (d) Cl 2p, (e) Cu 2p, (f) In 3d, (g) S2S, (h) Ni 2 p.

FIG. 3 is the NiS/CuInS of example 1₂A photoelectric reaction schematic diagram of a/BiOCl electrode.

FIG. 4 is the NiS/CuInS in example 3₂The timing current and the linear sweep voltammetry curve of the/BiOCl electrode; wherein (a) BiOCl, CuInS₂BiOCl and NiS/CuInS₂Comparison graph of chronoamperometry of a/BiOCl optimal electrode; (b) NiS/CuInS₂Current-voltage curves of/BiOCl under light and dark conditions.

FIG. 5 shows NiS/CuInS in example 4₂Stability analysis chart of/BiOCl electrode; wherein (a) NiS/CuInS₂a/BiOCl photocathode in a buffer solution saturated in air (pH 6) under visible light irradiation with cyclic voltammogram (50 cycles); (b) NiS/CuInS₂a/BiOCl photocathode in a buffer solution saturated with air and nitrogen (pH 6), -an applied voltage of 0.5V vs. ag/AgCl, current-time curve under visible light irradiation.

FIG. 6 shows the uncalcined BiOCl electrode obtained in comparative example 1, the calcined BiOCl and CuInS obtained in example 1₂Comparative XRD patterns of/BiOCl electrodes.

Figure 7 is a chronoamperometric graph of an uncalcined BiOCl electrode of control example 1 and a calcined BiOCl electrode of example 1.

FIG. 8 shows the different CuInS in example 1 and example 5₂Adsorption cycle times (0-4) CuInS₂a/BiOCl electrode and chronoamperometry.

FIG. 9 is the NiS/CuInS for different NiS illumination times in examples 1 and 6₂a/BiOCl electrode and chronoamperometry.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the invention and is not intended to limit the invention thereto.

Example 1

Preparation of NiS/CuInS₂A method of manufacturing a/BiOCl electrode, comprising the steps of:

(1) pretreating the FTO glass of the conductive substrate:

first, KOH was added to heated boiling isopropanol until it was completely dissolved to form a 2M KOH isopropanol solution. Pieces of FTO conductive glass (2 cm. times.1 cm) were then transferred to the solution and heated again to boil for 20 min. Because the boiling point of the isopropanol is low, a condensing tube reflux device is arranged in the whole heating process. And taking out the treated FTO conductive glass, and then respectively putting the treated FTO conductive glass into acetone, deionized water and absolute ethyl alcohol for ultrasonic cleaning twice, wherein the cleaning time is 15min each time, so as to ensure that residues such as potassium hydroxide on the surface of the FTO conductive glass are completely cleaned. And finally, putting the cleaned FTO glass into an oven, drying for 10min at the temperature of 110 ℃, and taking out for later use.

(2) Preparation of BiOCl electrode:

the BiOCl electrode is synthesized by adopting a solvothermal method, and specifically comprises the following steps: firstly, 10mmol of Bi (NO) is taken₃)·5H₂O in 20.0mL Ethylene Glycol (EG), while 10mmol NaCl in 20.0mL methanol; mixing and stirring the two solutions for 2 hours to obtain a transparent solution; placing the FTO conductive glass in the step (1) in a transparent solution to form a certain angle with the inner wall of an 80.0mL Teflon substrate, wherein the conductive surface faces downwards; reacting at 180 deg.C for 8h, taking out electrode, washing with ultrapure water for 2-3 times, and drying in ambient air; then calcining the electrode in Ar atmosphere in a tube furnace at 350 ℃ for 2 hours; thus obtaining the BiOCl electrode.

(3)CuInS₂Preparation of a/BiOCl electrode:

sequentially immersing the BiOCl electrode in the step (2) into CuCl₂、Na₂S、InCl₃、Na₂Each time for 1min in the adsorption solution of S, taking out the electrode and washing each time, and then immersing the electrode into the next adsorption solution, wherein the operation marks are a cycle; by controlling the cycle number to be 3, drying after adsorption is finished, and preparing the CuInS₂a/BiOCl electrode sample; wherein CuCl₂The concentration of the solution was 5mM, Na₂The concentration of the S solution was 50mM, InCl₃The concentration of the solution is 5 mM; drying the CuInS₂Calcining the/BiOCl electrode sample in a tubular furnace with Ar atmosphere at 400 ℃ for 30min to obtain CuInS₂a/BiOCl electrode.

(4)NiS/CuInS₂Preparation of/BiOCl electrode

Putting nickel acetate (final concentration of 35mM), thiourea (final concentration of 5mM), 4mL of absolute ethanol and 20mL of water into a 25mL round-bottom flask, and addingCuInS of step (3)₂the/BiOCl electrode is fixed in a round-bottom flask by a metal clamp and sealed; the system was degassed with nitrogen for 40min to remove air. At room temperature, adding CuInS₂The front surface of the/BiOCl electrode is aligned with a 300W xenon lamp for illumination for 20min, and the obtained NiS/CuInS is obtained after the illumination reaction is finished₂Taking out the/BiOCl electrode, repeatedly washing with water and drying to obtain NiS/CuInS₂a/BiOCl electrode.

The obtained NiS/CuInS₂The structure of the/BiOCl electrode is characterized, an XRD pattern is shown in figure 1, an XPS pattern is shown in figure 2, and the XRD pattern and the XPS pattern can be seen from figures 1 and 2: example 1 preparation of NiS/CuInS₂a/BiOCl electrode.

Example 1 preparation of the resulting NiS/CuInS₂The photochemical reaction principle diagram of the/BiOCl electrode is shown in figure 3, NiS/CuInS₂The good photoelectrochemical performance of the/BiOCl photocathode is mainly benefited by the fact that BiOCl and NiS simultaneously inhibit carrier recombination and accelerate the transfer of electrons and holes, and the specific characteristics are as follows. According to the interfacial electron transfer theory of Gerischeris, effective charge transfer between semiconductors depends largely on the overlap of the distribution function of excited states with the density of semiconductor states (DOS). The position of the conduction band of BiOCl is-1.1V vs. NHE, CuInS₂The valence band position of (a) is-2V vs. CuInS electrode surface₂Absorption of light gains energy that is excited to generate electron-hole pairs. Electron in CuInS₂The conduction band of (a) undergoes a transition and then is transferred to water by the action of the NiS promoter. Hole through CuInS₂Into the conduction band of BiOCl. CuInS₂Is much smaller than the conduction band position of BiOCl. Thus, there is an energy barrier in preventing conduction of electrons to the conduction band of BiOCl. Under the action of external voltage, electrons in the circuit consume holes conducted to a BiOCl conduction band, so that recombination of electron-hole pairs is reduced, and the electrons are promoted to be transferred to electrolyte to reduce hydrogen protons.

Example 2 NiS/CuInS₂Catalytic activity of/BiOCl electrode

The prepared NiS/CuInS₂the/BiOCl electrode is placed in a 100mL photocatalytic reactor and is used as a working electrode, a silver chloride electrode is used as a reference electrode, and a platinum electrode is usedA three-electrode system was constructed as a counter electrode, followed by the addition of 50mL of sodium sulfate solution as an electrolyte solution. Degassing with nitrogen gas for 1h before hydrogen production to remove oxygen in the system, placing the reaction cell under 300W xenon light (equipped with AM 1.5G optical filter) for irradiation, detecting hydrogen gas generated in the reaction by using thermal conductivity-gas chromatography after the reaction is finished, wherein the hydrogen production rate is 0.048 mu mol/h after the reaction is carried out for 1 h.

Example 3 NiS/CuInS₂Chronoamperometric and linear sweep voltammetric curve analysis of/BiOCl electrodes

Mixing BiOCl and CuInS₂BiOCl and NiS/CuInS₂the/BiOCl electrodes were tested for their chronoamperometry and linear sweep voltammograms at an applied voltage of 0V vs. ag/AgCl in an air saturated electrolyte solution (pH 7).

The results are shown in FIG. 4, where (a) is BiOCl, CuInS₂BiOCl and NiS/CuInS₂Comparison graph of chronoamperometry of a/BiOCl optimal electrode; and (3) testing conditions are as follows: the electrolyte solution is a buffer solution (pH is 6) of saturated air, the applied voltage is 0V vs. NHE, and the light source is a 300W xenon lamp for intermittent illumination; (b) is NiS/CuInS₂The current-voltage curve of BiOCl under light and dark conditions; and (3) testing conditions are as follows: the electrolyte solution was a buffer solution (pH 6) of saturated air, and the light source was a 300W xenon lamp. As can be seen from fig. 4: BiOCl electrodes produced little current, whether in the dark or light conditions, however due to CuInS₂The light absorption performance is excellent, and BiOCl quickly transfers holes, so that CuInS is reduced₂Recombination of internal charges, CuInS₂the/BiOCl photocathode generates nearly-90 mu A cm^-2Has good stability. After NiS is introduced, the electron transfer from the electrode surface to the electrolyte is further accelerated, and NiS/CuInS₂The photocurrent density generated by the/BiOCl photocathode almost reaches CuInS₂Twice of/BiOCl photocathode, -150 mu A cm^-2. As shown in FIG. 4(b), NiS/CuInS₂The current-voltage curve of the/BiOCl photocathode shows that the photocurrent of the electrode under the illumination condition is obviously higher than that of the electrode under the dark condition in the voltage range of-0.1 to-0.6V (vs. Ag/AgCl), and NiS/CuInS₂/BiOCl electrodeCurrent at 0V vs. RHE-1.2 mA cm^-2. Combining the above experimental results, NiS/CuInS₂the/BiOCl electrode is a high-efficiency photocathode.

Example 4 NiS/CuInS₂Stability analysis of/BiOCl electrodes

In an air-saturated buffer solution (pH 6) under AM 1.5G at 10mv s^-1The sweep rate of (A) was tested for NiS/CuInS₂The current density-potential curve of the cyclic voltammetry of the/BiOCl electrode. The curves measured for 50 cycles were highly coincident, indicating that NiS/CuInS was produced₂the/BiOCl electrode had excellent stability (FIG. 5 (a)).

Test NiS/CuInS₂0.5M Na saturated in air for/BiOCl electrode₂SO₄The photocurrent density at 0V vs. nhe in the solution was plotted against time (fig. 5 (b)). As can be seen from the figure: NiS/CuInS when tested up to 20000s (5.5h)₂The photocurrent density of the/BiOCl electrode is only slightly reduced from the initial value.

Comparative example 1

Omitting the calcination of the BiOCl electrode of step (2) in example 1 (and then calcining the electrode in Ar atmosphere in a tube furnace at 350 ℃ for 2 hours), the other steps were identical to those of example 1 to obtain an electrode having an XRD pattern as shown in FIG. 6

FIG. 7 is a chronoamperometric graph of an uncalcined BiOCl electrode of control example 1 and a calcined BiOCl electrode of example 1; and (3) testing conditions are as follows: the electrolyte solution is Na of saturated air₂SO₄The solution (pH 7) was applied with a voltage of 0V vs. nhe and the light source was an interrupted 300W xenon lamp. As can be seen from fig. 7: when the light source was turned off, the current density of the uncalcined BiOCl electrode of comparative example 1 was unstable, whereas the current density-time curve of the electrode became smooth and the dark current decreased after annealing the BiOCl electrode of example 1 at 350 ℃ for 2 hours; when the light source was turned on, the photocurrent density of the non-calcined BiOCl electrode of comparative example 1 hardly changed with respect to the dark current density, while the photocurrent density of the calcined BiOCl electrode of example 1 rapidly increased to-9. mu.A cm^-2. Therefore, the photoelectrochemical performance of the calcined BiOCl electrode is improved.

Example 5

Adjusting the cycle times in the step (3) in the example 1 to be 0, 1, 2 and 4, and keeping the rest consistent with the example 1 to obtain the NiS/CuInS₂a/BiOCl electrode.

FIG. 8 shows the different CuInS in example 1 and example 5₂Adsorption cycle times (0-4) CuInS₂a/BiOCl electrode and chronoamperogram; and (3) testing conditions are as follows: the electrolyte solution is Na of saturated air₂SO₄The solution (pH 7) was applied with a voltage of 0V vs. nhe and the light source was an interrupted 300W xenon lamp. As can be seen from fig. 8: CuInS₂And the electrode and BiOCl gain mutually, so that the photocurrent density of the electrode is improved. When the adsorption cycle number is 3, CuInS₂The amount adsorbed is optimized, when the measured CuInS₂The photocurrent value of the/BiOCl electrode was also maximized, and the optimum photocurrent value increased to-92. mu.A-cm^-2. However, when CuInS₂When the amount is excessive, the electron transport distance between the electrode and the interface of the electrolyte solution is increased to decrease the photocurrent density of the electrode.

Example 6

Adjusting the illumination time of the step (4) in the example 1 to be 0, 5, 10, 15 and 25min, and keeping the rest consistent with the example 1 to obtain NiS/CuInS₂a/BiOCl electrode.

FIG. 9 is the NiS/CuInS for different NiS illumination times in examples 1 and 6₂a/BiOCl electrode and chronoamperogram; and (3) testing conditions are as follows: the electrolyte solution is Na of saturated air₂SO₄The solution (pH 7) was applied with a voltage of 0V vs. nhe and the light source was an interrupted 300W xenon lamp. As can be seen from fig. 9: as the deposition amount of NiS increases, the charge transfer rate of the electrode increases and the photocurrent density value also increases. However, when the deposition of NiS is excessive, NiS may cover the electrode surface active sites, inhibiting the absorption of light. When the deposition time is 20min, NiS/CuInS₂The performance of the/BiOCl electrode is optimal, and NiS/CuInS₂The optimal photocurrent density value of the/BiOCl electrode can reach-150 muA-cm^-2Nhe under simulated sunlight and 0V vs, this is much higher than CuInS under the same conditions₂Photocurrent density values of/BiOCl electrodes.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.