A method for preparing a BiVO4 / CoOx / VO2 / FeOOH photoanode composite material and its application in an artificial leaf device.

Abstract

The application discloses a BiVO4 / CoO x / VO2 / FeOOH photoanode composite material preparation method and artificial leaf device application, and belongs to the technical field of new energy materials. x By introducing CoO x and VO2 as a synergistic hole storage layer, the photoanode can realize effective storage and regulation of photo-generated holes in different potential intervals, thereby promoting the spatial separation of photo-generated carriers, inhibiting electron-hole recombination, and significantly improving the photocurrent density of the photoanode. x In addition, FeOOH is further introduced as an oxygen evolution assistant catalyst to improve the water oxidation reaction kinetics, and a BiVO4 / CoO x / VO2 / FeOOH composite photoanode is constructed. By integrating with a silicon photovoltaic cell, an artificial leaf device is formed, which exhibits excellent photoelectrocatalytic activity and long-term operation stability in the process of photoelectrochemical water splitting.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, and relates to a photoanode catalytic material with a dual-hole storage layer, an artificial leaf device, and its application. Background Technology

[0002] Photoelectrochemical (PEC) water splitting technology, which directly converts solar energy into clean hydrogen energy, is considered one of the key pathways to solving the global energy crisis and environmental problems. The core of this technology lies in developing efficient and stable photoelectrocatalytic materials to improve the conversion efficiency of solar energy to chemical energy.

[0003] Among numerous semiconductor materials, bismuth vanadate (BiVO4) can absorb sunlight and generate photogenerated charges, thereby effectively degrading nitric oxide and nitrogen dioxide in the atmosphere and converting these harmful gases into harmless substances. Furthermore, BiVO4 performs exceptionally well in water splitting applications, as photogenerated holes can oxidize water to form oxygen. In addition, as a typical n-type semiconductor, BiVO4 possesses a suitable bandgap (~2.4 eV, effectively absorbing visible light) and a high theoretical photocurrent density (7.5 mA / cm²). 2 BiVO4 has become a research hotspot in the field of PEC water oxidation due to its advantages such as high density of photogenerated charge recombination (hole diffusion length in bulk is only ~75 nm), large interfacial charge transfer resistance, and sluggish oxygen evolution reaction (OER) kinetics. However, its catalytic activity is severely limited by problems such as severe photogenerated charge recombination (hole diffusion length in bulk is only ~75 nm), large interfacial charge transfer resistance, and slow surface oxygen evolution reaction (OER) kinetics. Even when a co-catalyst (OEC) such as NiFe-based oxide / hydroxide is loaded on the BiVO4 surface, its photocurrent density is still far below the theoretical maximum value. The root cause is that the BiVO4 / OEC interface is prone to high-density defect states, band mismatch, and Fermi level pinning, which makes it difficult for photogenerated holes to be injected from the BiVO4 bulk phase or surface to the OER active sites in a timely and effective manner. Instead, severe nonradiative recombination occurs in the interfacial region.

[0004] To address these bottlenecks, researchers have proposed strategies such as introducing hole transport layers, constructing heterojunction interfaces, and interface passivation layers. Among these, the introduction of a hole storage layer (HSL) has proven to be an effective means of suppressing charge recombination and improving hole utilization. By temporarily storing photogenerated holes and directionally transporting them to OER active sites, nonradiative recombination of electron-hole pairs can be significantly reduced. Currently reported hole storage layers are mostly single-component (such as NiFe-LDH, FeOOH, carbon-based materials, etc.). Although they can improve hole storage capacity in specific potential ranges, they generally suffer from the limitation of "single potential range adaptability": that is, a single HSL can only match the generation and transport dynamics of holes within a specific potential range, and cannot cover the full range of hole requirements of BiVO4 in the PEC water oxidation process from low to high potentials. This limitation leads to the recombination of holes in some potential ranges due to the inability to store them in time, becoming a key obstacle restricting further improvement of BiVO4 charge separation efficiency. Therefore, developing a composite storage layer with wide potential range adaptability and the ability to cover the dynamic hole requirements across the entire potential range is key to further breaking through the bottleneck of BiVO4 charge separation efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a BiVO4 / CoO x The preparation method of / VO2 / FeOOH photoanode composite material and its application in artificial leaf device are proposed to solve the problem that the single hole storage layer in the existing BiVO4 photoelectrocatalytic material cannot achieve hole storage and transport over a wide potential range.

[0006] This invention provides a BiVO4 / CoO x The / VO2 / FeOOH photoanode composite material includes a transparent conductive substrate, a BiVO4 semiconductor light-absorbing material grown on the transparent conductive substrate, and a dual-hole storage layer with voltage-divided intervals covering the surface of the BiVO4 light-absorbing material, wherein the dual-hole storage layers with voltage-divided intervals are cobalt oxide and vanadium oxide, respectively; the BiVO4 / CoO2 / FeOOH photoanode composite material includes a transparent conductive substrate, a BiVO4 semiconductor light-absorbing material grown on the transparent conductive substrate, and a dual-hole storage layer with voltage-divided intervals covering the surface of the BiVO4 light-absorbing material. x The / VO2 / FeOOH photoanode composite material has a layered structure, including a substrate, a BiVO4 layer, and a CoO layer with hole storage function. x The catalyst layer consists of VO2 and FeOOH, with x ranging from 1 to 2.

[0007] This invention utilizes CoO x In the low potential range (0.6V-1.4V vs. RHE), through Co 2+ / Co 3+ / Co 4+ Multi-valence reversible transmutation enables rapid hole capture; VO2 in the high potential range (0.9V-1.6V vs. RHE) via V4+ / V 5+ Valence state cycles replenish hole storage sites, constructing a hole storage network with "low-high potential full coverage".

[0008] This invention provides the above-mentioned BiVO4 / CoO x The preparation method of / VO2 / FeOOH photoanode composite material includes the following steps: (1) A BiOI thin film was electrodeposited on the substrate surface. After adding acetylacetone vanadium oxide solution to the surface of the BiOI thin film, it was calcined at high temperature and soaked in alkaline solution to obtain a BiVO4 thin film substrate layer. (2) Using cobalt acetate aqueous solution as electrolyte, a three-electrode system was used to electrodeposit CoO on the surface of BiVO4 thin film at a constant potential. x The loading was adjusted by controlling the deposition time, and the BiVO4 / CoO layer was obtained after annealing. x Photoanode; (3) In BiVO4 / CoO x On the photoanode surface, using a solution of V₂O₅ and H₂O₂ as a precursor, photoelectrochemical deposition was performed under simulated sunlight irradiation and a constant potential. By adjusting the deposition potential and time, the VO₂ layer was optimized to obtain BiVO₄ / CoO₂. x / VO2 photoanode; (4) In BiVO4 / CoO x On the surface of the / VO2 photoanode, using a nitrogen-protected FeSO4 aqueous solution as the electrolyte, photo-assisted electrodeposition was performed under simulated sunlight irradiation and constant potential. Three consecutive deposition cycles were carried out to finally obtain BiVO4 / CoO2. x / VO2 / FeOOH multilayer photoanodic composite material.

[0009] Preferably, the substrate in step (1) is a transparent conductive oxide material FTO glass; the substrate needs to be pretreated before use. The specific operation method is as follows: the substrate is ultrasonically cleaned with cleaning agent, acetone, ethanol and deionized water for 10 min to 15 min in sequence, and then soaked in ethanol for later use.

[0010] The electrolyte for electrodeposition is obtained by mixing a potassium iodide solution of bismuth nitrate and a p-benzoquinone solution, wherein the concentration of bismuth nitrate in the potassium iodide solution is 0.03 mol / L to 0.05 mol / L, preferably 0.035 mol / L to 0.045 mol / L, and more preferably 0.04 mol / L; the concentration of potassium iodide is 0.3 mol / L to 0.5 mol / L, preferably 0.33 mol / L to 0.48 mol / L, more preferably 0.35 mol / L to 0.45 mol / L, and more preferably... The concentration of the potassium iodide solution containing bismuth nitrate is 0.4 mol / L; the pH of the potassium iodide solution containing bismuth nitrate is adjusted to 1.5~2, preferably 1.7, by adding nitric acid; the concentration of the p-benzoquinone solution is 0.18 mol / L~0.28 mol / L, preferably 0.20 mol / L~0.26 mol / L, more preferably 0.22 mol / L~0.25 mol / L, and more preferably 0.23 mol / L; the volume ratio of the potassium iodide solution containing bismuth nitrate to the p-benzoquinone solution is 3~10:1~5, preferably 4~8:2~4, and more preferably 5:2.

[0011] Preferably, the electrodeposition in step (1) is performed in a three-electrode system, wherein the substrate is the working electrode, the Ag / AgCl (saturated KCl) electrode is the reference electrode, and the Pt electrode is the counter electrode; the deposition potential of the electrodeposition is -0.05V to -0.15V vs. AgCl, preferably -0.07V to -0.13V vs. AgCl, more preferably -0.09V to -0.11V vs. AgCl, and more preferably -0.1V vs. AgCl; the electrodeposition time is 2min to 5min, preferably 2.5min to 4.5min, more preferably 3min to 4min, and more preferably 3min.

[0012] Preferably, the concentration of the vanadium acetylacetonate solution (a solution formed by dissolving vanadium acetylacetonate in dimethyl sulfoxide) in step (1) is 0.15 mol / L to 0.25 mol / L, more preferably 0.18 mol / L to 0.23 mol / L, and even more preferably 0.2 mol / L; the amount of vanadium acetylacetonate solution added based on the BiOI film is 50 μL / cm. 2 ~150μL / cm 2 Preferably 70 μL / cm 2 ~130μL / cm 2 More preferably 90 μL / cm 2 ~110μL / cm 2 More preferably 100 μL / cm 2 .

[0013] Preferably, the high-temperature calcination temperature in step (1) is 400℃~500℃, more preferably 440℃~460℃, and even more preferably 450℃; the high-temperature calcination time is 1h~3h, more preferably 1.5h~2.5h, and even more preferably 2h; the alkaline solution in the alkaline soaking is a sodium hydroxide solution with a concentration of 0.5mol / L~2mol / L, more preferably 0.6mol / L~1.8mol / L, even more preferably 0.8mol / L~1.5mol / L, and even more preferably 1mol / L; the alkaline soaking temperature is 20℃~30℃, more preferably 22℃~28℃, and even more preferably 25℃; the soaking time is 1min~60min, more preferably 10min~50min, even more preferably 20min~40min, and even more preferably 30min.

[0014] Preferably, the electrolyte in step (2) is a 0.02 M to 0.03 M cobalt acetate aqueous solution.

[0015] Preferably, the deposition process in step (2) is carried out using a three-electrode system under a constant potential of 0.25 V (vs. Ag / AgCl) for a deposition time of 20 s to 120 s. The difference between the three-electrode system used here and that in step (1) is that the working electrode is a BiVO4 thin film.

[0016] Preferably, the annealing in step (2) is carried out in an air atmosphere, and the annealing temperature is 400℃~600℃, preferably 450℃~550℃; the annealing time is 1h~3h, preferably 1.5h~3h, and more preferably 1.5h~2.5h.

[0017] The preferred preparation process in step (2) is: CoO x The deposition of the layer was performed using a typical three-electrode system, with a BiVO4 thin film as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 25 × 10⁻⁶. -3 MCH3COO2Co·4H2O aqueous solution. The deposition process was carried out under constant potential conditions of 0.25 V (vs. Ag / AgCl), and the CoO content was adjusted by controlling the deposition time. x The loading amount was determined. After deposition, the resulting film was annealed in air at 400℃~600℃ for 1h~3h to obtain BiVO4 / CoO4. x Photoanode.

[0018] Preferably, the electrolyte in step (3) is a potassium tetraborate precursor solution containing vanadium pentoxide (V2O5) and hydrogen peroxide (H2O2); the precursor solution is prepared by adding V2O5 powder to a potassium tetraborate aqueous solution and adding H2O2 to react and dissolve it to form a homogeneous solution. In the precursor solution, the concentration of V2O5 is 0.05 mol / L to 0.15 mol / L, preferably 0.1 mol / L; the concentration of the potassium tetraborate aqueous solution is 0.2 mol / L to 0.8 mol / L, preferably 0.5 mol / L; and the volume of H2O2 added is 1.0 mL to 2.0 mL, preferably 1.5 mL, based on 100 mL of the precursor solution.

[0019] The deposition potential is adjusted to 1.2V~2.0V vs. RHE, preferably 1.4V~1.8V vs. RHE, and more preferably 1.6V vs. RHE; the deposition time is 15min~45min, preferably 25min~35min, and more preferably 30min. The difference between the three-electrode system and step (2) is that it uses BiVO4 / CoO4. x The thin film serves as the working electrode. An Ag / AgCl electrode is used during deposition, and RHE is a reversible hydrogen electrode.

[0020] Preferably, the electrolyte preparation process in step (4) is as follows: FeSO4·7H2O is used as raw material, and after deionized water is purged with nitrogen for 30 min, FeSO4·7H2O is added to prepare a FeSO4 solution with a concentration of 0.005 M to 0.015 M, preferably with a concentration range of 0.01 M.

[0021] The electrodeposition in step (4) is performed in a three-electrode system, wherein BiVO4 / CoO x The / VO2 thin film is used as the working electrode, the Ag / AgCl electrode as the reference electrode, and the Pt electrode as the counter electrode; the deposition potential for one deposition cycle is 0.05V ~ 0.45V vs. Ag / AgCl, preferably 0.1V ~ 0.4V vs. Ag / AgCl, more preferably 0.15V ~ 0.3V vs. Ag / AgCl, and even more preferably 0.25V vs. Ag / AgCl; the electrodeposition time is 20min ~ 40min, preferably 30min; three deposition cycles are performed continuously; freshly prepared FeSO4·7H2O solution is used in each cycle.

[0022] The illumination source mentioned in step (4) is a 300 W xenon lamp with an AM 1.5G filter and a light intensity of 50 mW·cm. -2 ~150mW·cm -2Preferably 100 mW·cm -2 It is incident from the base side of the FTO.

[0023] This invention provides the above-mentioned BiVO4 / CoO x Application of / VO2 / FeOOH photoanode composite material in photoelectrochemical water splitting. Specific application methods are as follows: using BiVO4 / CoO2... x A three-electrode system is constructed using a / VO2 / FeOOH photoanode composite material as the working electrode, a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. Potassium borate solution is used as the electrolyte for photoelectrocatalytic water splitting under light irradiation and an applied bias voltage. In this application, the concentration of the potassium borate solution is 0.1 mol / L to 1.0 mol / L, preferably 0.2 mol / L to 0.8 mol / L, more preferably 0.4 mol / L to 0.6 mol / L, and even more preferably 0.5 mol / L. The light source for the light irradiation is an AM 1.5G xenon lamp with an irradiance of 10 mW / cm². 2 ~150mW / cm 2 The preferred value is 30mW / cm 2 ~130mW / cm 2 Further preferred is 50mW / cm 2 ~110mW / cm 2 More preferably 80mW / cm 2 ~100mW / cm 2 The applied bias voltage is 1.23 V vs. RHE.

[0024] This invention provides a method based on BiVO4 / CoO x The artificial leaf device is made of BiVO4 / CoO2 / FeOOH photoanode composite material. x The device integrates a / VO2 / FeOOH photoanode composite material, a Pt wafer, and a silicon solar cell. The silicon solar cell is placed on the side of the photoanode and connected in series with the working anode and cathode to power them, eliminating the need for an external voltage during application. The original design of the artificial leaf device incorporated the base layer structure as a component of the artificial leaf system.

[0025] This invention provides the application of the aforementioned artificial leaf device in the production of hydrogen and oxygen through water splitting. The specific application is as follows: A potassium borate solution is used as the electrolyte. The artificial leaf device is placed in the electrolyte, and water is split photoelectrochemically under light irradiation. In this application, the concentration of the potassium borate solution is 0.1 mol / L to 1.0 mol / L, preferably 0.2 mol / L to 0.8 mol / L, more preferably 0.4 mol / L to 0.6 mol / L, and even more preferably 0.5 mol / L; the light source for the light irradiation is an AM1.5G xenon lamp with an irradiance of 10 mW / cm². 2 ~150mW / cm 2 The preferred value is 30mW / cm 2 ~130mW / cm 2 Further preferred is 50mW / cm 2 ~110mW / cm 2 More preferably 80mW / cm 2 ~100mW / cm 2 .

[0026] The beneficial effects of this invention are: (1) The BiVO4 / CoO4 prepared in this invention x The / VO2 / FeOOH photoanode composite material exhibits good photocatalytic activity and stability; (2) The preparation method of the present invention is to prepare photoanode composite material with multilayer structure by electrodeposition. This method has the advantages of being inexpensive, simple, safe, green and easy to operate. (3) In this invention, BiVO4 / CoO x The good onset potential, high performance and stability of the / VO2 / FeOOH photoanode indicate that it has good potential for unbiased PEC water splitting when coupled with photovoltaic devices. (4) In this invention, CoO with different hole storage capacities in different voltage ranges is sequentially modified on the surface of BiVO4. x The VO2 layer enables temporal genomic control and effective separation of photogenerated holes; subsequently, a FeOOH co-catalyst layer is introduced to improve the kinetics of surface water oxidation reaction, thereby enhancing the photoelectrocatalytic performance of the composite photoanode. (5) The present invention BiVO4 / CoO x The combination of / VO2 / FeOOH photoanode composite material and silicon solar cell exhibits excellent long-term stability, and the solar-to-hydrogen conversion efficiency of the unbiased artificial leaf device reaches 7.27%. Attached Figure Description

[0027] Figure 1 BiVO4 and BiVO4 / CoO prepared in Example 1x BiVO4 / CoO x / VO2 and BiVO4 / CoO x Scanning electron microscope (SEM) images of the / VO2 / FeOOH photoanode, a for BiVO4, b for BiVO4 / CoO2. x c represents BiVO4 / CoO x / VO2, d is BiVO4 / CoO x / VO2 / FeOOH; Figure 2 BiVO4 and BiVO4 / CoO4 prepared under different applied bias voltages, as well as BiVO4 / CoO4 prepared in Comparative Example 2. x BiVO4 / VO2 prepared in Comparative Example 3 and BiVO4 / CoO2 prepared in Comparative Example 4 x Linear scan curve of / VO2 photoanode; Figure 3 The graphs show the photocurrent delay and charge storage capacity curves of different photoanodes, where a represents BiVO4 and BiVO4 / CoO4 prepared in Comparative Example 2. x BiVO4 / VO2 prepared in Comparative Example 3 and BiVO4 / CoO2 prepared in Comparative Example 4 x / VO2 photoanode under simulated sunlight at AM1.5G (100mW / cm²) 2 Under irradiation, the cathode photocurrent delay curves were measured at 0.4 V vs. RHE conditions, and b is the charge storage capacity curve under different applied bias voltages. Figure 4 For CoO x Cyclic voltammetry curves of the oxygen evolution reaction process at the VO2 electrode, where a represents CoO2. x Cyclic voltammetry curves of the electrode releasing Co ions in the oxygen evolution reaction process, and cyclic voltammetry curves of the VO2 electrode releasing V ions in the oxygen evolution reaction process. Figure 5 BiVO4 and BiVO4 / CoO4 prepared in Comparative Example 2 x BiVO4 / VO2 prepared in Comparative Example 3 and BiVO4 / CoO2 prepared in Comparative Example 4 x SPV spectrum of / VO2 photoanode; Figure 6 BiVO4 / CoO x / VO2 photoanode CoO x A schematic diagram of the hole storage mechanism of the VO2 hole storage layer; Figure 7 BiVO4 / CoO x / VO2 and BiVO4 / CoO xElectrochemical performance and stability test results of the / VO2 / FeOOH photoanode, where a represents the BiVO4 / CoO2 / FeO2 photoanode under different applied bias voltages. x / VO2 and BiVO4 / CoO x The electrode linear scan curve of / VO2 / FeOOH, b is the BiVO4 / CoO x Curve of current density versus time for / VO2 / FeOOH at 1.23V vs. RHE; Figure 8 This is a schematic diagram illustrating the application of the artificial leaf device; where a represents the BiVO4 / CoO4 prepared in Example 1. x Schematic diagram of a PV-PEC series cell with a / VO2 / FeOOH photoanode and silicon solar cell, b shows the assembly scheme of the artificial leaf device, c and d are images of the artificial leaf, e is a BiVO4 / CoO2 / Fe ... x JV curves of a bipolar BiVO₄ / FeOOH photoanode-platinum cathode and silicon solar cell, where f represents the linear BiVO₄ / CoO₂ solar cell. x Photocurrent density-time curve of / VO2 / FeOOH-PV artificial leaves, g represents the photocurrent density of wireless BiVO4 / CoO2 / FeOOH-PV artificial leaves under AM 1.5G irradiation. x The corresponding H2 and O2 production curves for / VO2 / FeOOH-PV artificial leaves. Detailed Implementation

[0028] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention. Example 1

[0029] (1) First, BiOI nanofilms were prepared by electrodeposition using a CHI 660E electrochemical workstation. The specific steps were as follows: FTO conductive glass, which had been ultrasonically cleaned (for 15 min) sequentially with detergent, acetone, ethanol, and water, was used as the working electrode, Ag / AgCl (saturated KCl solution) electrode was used as the reference electrode, and Pt electrode was used as the counter electrode. 2 mmol Bi(NO3)3·5H2O was dissolved in 50 mL of 0.4 mol / L KI solution, and the pH was adjusted to 1.7 with concentrated nitric acid (16 mol / L). The solution was stirred until it became a clear orange-red solution. Then, 20 mL of 0.23 mol / L p-benzoquinone ethanol solution was slowly added and stirred for 5 min until the solution turned blood red. This blood-red solution was used as the electrolyte. Electrodeposition was performed at a constant potential of -0.1 V vs. AgCl for 3 min to obtain BiOI nanofilms. The obtained BiOI nanofilms were then rinsed with distilled water.

[0030] Subsequently, a BiVO4 substrate layer was prepared by calcination. The specific steps were as follows: 0.10 mL of a 0.2 mol / L vanadium acetylacetonate dimethyl sulfoxide solution was dropped onto the prepared BiOI nanofilm (1 cm²). 2 The electrode was heated to 450°C in a muffle furnace at a heating rate of 2°C / min and held at that temperature for 2 hours. After cooling to room temperature, the electrode was soaked in 1M NaOH solution for 15 minutes to remove excess V2O5, rinsed with a large amount of ultrapure water, and air-dried to obtain the BiVO4 substrate layer.

[0031] (2) The BiVO4 thin film was used as the working electrode, the platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 0.025... M cobalt acetate aqueous solution. Deposition was carried out at a constant potential of 0.25 V (vs. Ag / AgCl) for 80 s, followed by annealing at 500 °C for 2 h in air atmosphere to obtain BiVO4 / CoO. x Photoanode.

[0032] (3) Using BiVO4 / CoO x As the working electrode, a precursor solution was prepared by mixing V₂O₅ with 1.5 mL of H₂O₂ in a potassium tetraborate buffer solution at pH 9.3; the concentration of V₂O₅ in the precursor solution was 0.1 mol / L. Simulated sunlight (100 mW / cm²) was applied at AM 1.5G. -2 BiVO4 / CoO4 was obtained by deposition at a constant potential of 1.6 V vs. RHE for 30 min under irradiation. x / VO2 photoanode.

[0033] (4) Using BiVO4 / CoO x / VO2 was used as the working electrode, and a 0.01 M FeSO4 solution was prepared as the electrolyte. The specific method was as follows: deionized water was purged with nitrogen for 30 min, and then FeSO4·7H2O was added to prepare a 0.001 M FeSO4 solution. The solution was tested under AM 1.5G illumination (the light source was a 300 W xenon lamp equipped with an AM 1.5G filter, and the light intensity was calibrated to 100 mW cm⁻¹). -2 Photo-assisted electrodeposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl) for three consecutive deposition cycles (30 min per cycle, with freshly prepared electrolyte used in each cycle), ultimately yielding BiVO4 / CoO4. x / VO2 / FeOOH multilayer photoanode. Example 2

[0034] (1) First, BiOI nanofilms were prepared by electrodeposition using a CHI 660E electrochemical workstation. The specific steps were as follows: FTO conductive glass, which had been ultrasonically cleaned (for 13 min) sequentially with detergent, acetone, ethanol, and water, was used as the working electrode, Ag / AgCl (saturated KCl solution) electrode was used as the reference electrode, and Pt electrode was used as the counter electrode. 2.5 mmol Bi(NO3)3·5H2O was dissolved in 60 mL of 0.4 mol / L KI solution, and the pH was adjusted to 1.8 with concentrated nitric acid (16 mol / L). The solution was stirred until it became a clear orange-red solution. Then, 20 mL of 0.23 mol / L p-benzoquinone ethanol solution was slowly added and stirred for 5 min until the solution turned blood red. The blood red solution was used as the electrolyte. Electrodeposition was performed at a constant potential of -0.1 V vs. AgCl for 3 min to obtain BiOI nanofilms. The obtained BiOI nanofilms were then rinsed with distilled water.

[0035] Subsequently, a BiVO4 substrate layer was prepared by calcination. The specific steps were as follows: 0.15 mL of a 0.2 mol / L vanadium acetylacetonate dimethyl sulfoxide solution was dropped onto the prepared BiOI nanofilm (1 cm²). 2 The electrode was heated to 450°C in a muffle furnace at a heating rate of 2°C / min and held at that temperature for 2 hours. After cooling to room temperature, the electrode was soaked in 1M NaOH solution for 15 minutes to remove excess V2O5, rinsed with a large amount of ultrapure water, and air-dried to obtain the BiVO4 substrate layer.

[0036] (2) The above BiVO4 thin film was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a 0.028M cobalt acetate aqueous solution. Deposition was carried out at a constant potential of 0.25 V (vs. Ag / AgCl) for 40 s, followed by annealing at 550 °C for 2 h in air to obtain BiVO4 / CoO2. x Photoanode.

[0037] (3) Using BiVO4 / CoO x As the working electrode, a precursor solution was prepared by mixing V₂O₅ with 2 mL of H₂O₂ in a potassium tetraborate buffer solution at pH 9.3. The concentration of V₂O₅ in the precursor solution was 0.1 mol / L. Simulated sunlight (100 mW·cm⁻¹) was applied at AM 1.5G. -2 BiVO4 / CoO2 was obtained by deposition at a constant potential of 1.6 V vs. RHE for 15 min under irradiation. x / VO2 photoanode.

[0038] (4) Using BiVO4 / CoO x / VO2 was used as the working electrode, and FeSO4·7H2O was used as the raw material. A 0.015 M FeSO4 solution was prepared as the electrolyte in deionized water purged with nitrogen for 30 min. The electrode was operated under AM 1.5G illumination (the light source was a 300 W xenon lamp equipped with an AM 1.5G filter, and the light intensity was calibrated to 100 mW·cm). -2 Photo-assisted electrodeposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl) for three consecutive deposition cycles (30 min per cycle, with freshly prepared electrolyte used in each cycle), ultimately yielding BiVO4 / CoO4. x / VO2 / FeOOH multilayer photoanode. Example 3

[0039] (1) First, BiOI nanofilms were prepared by electrodeposition using a CHI 660E electrochemical workstation. The specific steps were as follows: FTO conductive glass, which had been ultrasonically cleaned (for 12 min) sequentially with detergent, acetone, ethanol, and water, was used as the working electrode, Ag / AgCl (saturated KCl solution) electrode was used as the reference electrode, and Pt electrode was used as the counter electrode. 1.5 mmol Bi(NO3)3·5H2O was dissolved in 50 mL of 0.4 mol / L KI solution, and the pH was adjusted to 1.6 with concentrated nitric acid (16 mol / L). The solution was stirred until it became a clear orange-red solution. Then, 20 mL of 0.23 mol / L p-benzoquinone ethanol solution was slowly added and stirred for 5 min until the solution turned blood red. The blood red solution was used as the electrolyte. Electrodeposition was performed at a constant potential of -0.1 V vs. AgCl for 3 min to obtain BiOI nanofilms. The obtained BiOI nanofilms were then rinsed with distilled water.

[0040] Subsequently, a BiVO4 substrate layer was prepared by calcination. The specific steps were as follows: 0.05 mL of a 0.2 mol / L vanadium acetylacetonate dimethyl sulfoxide solution was dropped onto the prepared BiOI nanofilm (1 cm²). 2 The electrode was heated to 440°C in a muffle furnace at a heating rate of 2°C / min and held at that temperature for 2 hours. After cooling to room temperature, the electrode was soaked in 1M NaOH solution for 30 minutes to remove excess V2O5, rinsed with a large amount of ultrapure water, and air-dried to obtain the BiVO4 substrate layer.

[0041] (2) The BiVO4 thin film was used as the working electrode, the platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 0.023... M cobalt acetate aqueous solution. Deposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl) for 80 s, followed by annealing at 560 °C for 2 h in air to obtain BiVO4 / CoO. x Photoanode.

[0042] (3) Using BiVO4 / CoO x As the working electrode, a precursor solution was prepared by mixing V₂O₅ with 1.8 mL of H₂O₂ in a potassium tetraborate buffer solution at pH 9.3. The concentration of V₂O₅ in the precursor solution was 0.11 mol / L. Simulated sunlight (100 mW·cm⁻¹) was applied at AM 1.5G. -2 BiVO4 / CoO4 was obtained by deposition at a constant potential of 1.2 V vs. RHE for 30 min under irradiation. x / VO2 photoanode.

[0043] (4) Using BiVO4 / CoO x / VO2 was used as the working electrode, and FeSO4·7H2O was used as the raw material. A 0.012M FeSO4 solution was prepared as the electrolyte in deionized water purged with nitrogen for 30 min. The system was illuminated under AM 1.5G light (the light source was a 300 W xenon lamp equipped with an AM 1.5G filter, and the light intensity was calibrated to 100 mW·cm). -2 Photo-assisted electrodeposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl) for three consecutive deposition cycles (30 min per cycle, with freshly prepared electrolyte used in each cycle), ultimately yielding BiVO4 / CoO4. x / VO2 / FeOOH multilayer photoanode. Example 4

[0044] (1) First, BiOI nanofilms were prepared by electrodeposition using a CHI 660E electrochemical workstation. The specific steps were as follows: FTO conductive glass, which had been ultrasonically cleaned (for 10 min) sequentially with detergent, acetone, ethanol, and water, was used as the working electrode, Ag / AgCl (saturated KCl solution) electrode was used as the reference electrode, and Pt electrode was used as the counter electrode. 2 mmol Bi(NO3)3·5H2O was dissolved in 50 mL of 0.4 mol / L KI solution, and the pH was adjusted to 2 with concentrated nitric acid (16 mol / L). The solution was stirred until it became a clear orange-red solution. Then, 20 mL of 0.23 mol / L p-benzoquinone ethanol solution was slowly added and stirred for 5 min until the solution turned blood red. This blood red solution was used as the electrolyte. Electrodeposition was performed at a constant potential of -0.1 V vs. AgCl for 3 min to obtain BiOI nanofilms. The obtained BiOI nanofilms were then rinsed with distilled water.

[0045] Subsequently, a BiVO4 substrate layer was prepared by calcination. The specific steps were as follows: 0.75 mL of a 0.2 mol / L vanadium acetylacetonate dimethyl sulfoxide solution was dropped onto the prepared BiOI nanofilm (1 cm²). 2The electrode was heated to 480°C in a muffle furnace at a heating rate of 2°C / min and held at that temperature for 2 hours. After cooling to room temperature, the electrode was soaked in 1M NaOH solution for 20 minutes to remove excess V2O5, rinsed with a large amount of ultrapure water, and air-dried to obtain the BiVO4 substrate layer.

[0046] (2) The above BiVO4 thin film was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a 0.025M cobalt acetate aqueous solution. Deposition was carried out at a constant potential of 0.25 V (vs. Ag / AgCl) for 20 s, followed by annealing at 450 °C for 2 h in air to obtain BiVO4 / CoO2. x Photoanode.

[0047] (3) Using BiVO4 / CoO x As the working electrode, a precursor solution was prepared by mixing V₂O₅ with 1.5 mL of H₂O₂ in a potassium tetraborate buffer solution at pH 9.3. The concentration of V₂O₅ in the precursor solution was 0.15 mol / L. Simulated sunlight (100 mW·cm⁻¹) was applied at AM 1.5G. -2 BiVO4 / CoO4 was obtained by deposition at a constant potential of 2.0 V vs. RHE for 30 min under irradiation. x / VO2 photoanode.

[0048] (4) Using BiVO4 / CoO x / VO2 was used as the working electrode, and FeSO4·7H2O was used as the raw material. A 0.015 M FeSO4 solution was prepared as the electrolyte in deionized water purged with nitrogen for 30 min. The electrode was operated under AM 1.5G illumination (the light source was a 300 W xenon lamp equipped with an AM 1.5G filter, and the light intensity was calibrated to 100 mW·cm). -2 Photo-assisted electrodeposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl) for three consecutive deposition cycles (30 min per cycle, with freshly prepared electrolyte used in each cycle), ultimately yielding BiVO4 / CoO4. x / VO2 / FeOOH multilayer photoanode.

[0049] Comparative Example 1 The BiVO4 substrate prepared in step (1) of Example 1 was used in a three-electrode system with the BiVO4 thin film as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode. A 0.01 M FeSO4·7H2O solution was prepared in deionized water purged with nitrogen for 30 min as the electrolyte. A 300 W xenon lamp equipped with an AM 1.5G filter was used as the light source, and the light intensity was calibrated to 100 mW cm⁻¹. -2Light is incident from the FTO substrate side, and photo-assisted electrodeposition is performed at a constant potential of 0.25 V (vs. Ag / AgCl). Three deposition cycles are performed continuously, each lasting 30 min. The electrolyte is replaced with fresh electrolyte each cycle. After deposition, the substrate is rinsed with deionized water and dried with nitrogen to obtain a BiVO4 / FeOOH composite photoanode.

[0050] The difference between this comparative example and Example 1 is that CoO is omitted. x With the use of the VO2 dual-hole storage layer, only the BiVO4 layer and the FeOOH layer are sequentially coated on the FTO conductive glass substrate.

[0051] Comparative Example 2 The BiVO4 substrate prepared in step (1) of Example 1 was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 25 × 10⁻⁶. -3 M cobalt acetate aqueous solution was deposited at a constant potential of 0.25 V (vs. Ag / AgCl) for 80 s, followed by annealing at 500 °C for 2 h in air atmosphere to obtain BiVO4 / CoO2. x Photoanode.

[0052] Then with BiVO4 / CoO x The working electrode was FeSO4, the reference electrode was Ag / AgCl, and the counter electrode was platinum wire. A 0.01 M FeSO4·7H2O solution was prepared in deionized water purged with nitrogen for 30 min as the electrolyte. A 300 W xenon lamp equipped with an AM 1.5G filter was used as the light source, and the light intensity was calibrated to 100 mW·cm. -2 Light was incident from the FTO substrate side, and photo-assisted electrodeposition was performed at a constant potential of 0.25 V (vs. Ag / AgCl). Three consecutive deposition cycles were performed, each lasting 30 minutes. The electrolyte was replaced with fresh electrolyte each cycle. After deposition, the substrate was rinsed with deionized water and dried under nitrogen to obtain BiVO4 / CoO4. x / FeOOH composite photoanode.

[0053] The difference between this comparative example and Example 1 is that only CoO is used. x As a single hole storage layer, this photoanode composite material consists of an FTO conductive glass substrate and a BiVO4 layer and a CoO layer sequentially covering the FTO conductive glass substrate. x It consists of a layer and an FeOOH layer.

[0054] Comparative Example 3 The BiVO4 substrate prepared in step (1) of Example 1 was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was a potassium tetraborate buffer solution with pH 9.3, with 0.1 M of a mixed precursor of V2O5 and H2O2 (molar ratio 1:4) added. Simulated sunlight at AM 1.5G (100 mW·cm⁻¹) was applied. -2 Under irradiation, a constant potential of 1.6 V vs. RHE was deposited for 30 min. After deposition, the sample was rinsed with ultrapure water and dried with nitrogen to obtain a BiVO4 / VO2 photoanode.

[0055] Then, using BiVO4 / VO2 as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode, a 0.01 M FeSO4·7H2O solution was prepared in deionized water purged with nitrogen for 30 min as the electrolyte. A 300 W xenon lamp equipped with an AM 1.5G filter was used as the light source, and the light intensity was calibrated to 100 mW·cm. -2 Light is incident from the FTO substrate side, and photo-assisted electrodeposition is performed at a constant potential of 0.25 V (vs. Ag / AgCl). Three deposition cycles are performed continuously, each lasting 30 minutes. The electrolyte is replaced with fresh electrolyte each cycle. After deposition, the substrate is rinsed with deionized water and dried with nitrogen to obtain a BiVO4 / VO2 / FeOOH composite photoanode.

[0056] The difference between this comparative example and Example 1 is that only VO2 is used as a single hole storage layer. This photoanode composite material consists of an FTO conductive glass substrate and a BiVO4 layer, a VO2 layer and a FeOOH layer sequentially covering the FTO conductive glass substrate.

[0057] Comparative Example 4 The BiVO4 substrate prepared in step (1) of Example 1 was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte was 25 × 10⁻⁶. -3 M cobalt acetate aqueous solution was deposited at a constant potential of 0.25 V (vs. Ag / AgCl) for 80 s, followed by annealing at 500 °C for 2 h in air atmosphere to obtain BiVO4 / CoO2. x Photoanode.

[0058] Then with BiVO4 / CoO x The electrode used is the working electrode, a platinum sheet is the counter electrode, and Ag / AgCl is the reference electrode. The electrolyte is a potassium tetraborate buffer solution with pH 9.3, with 0.1 M of a mixed precursor of V₂O₅ and H₂O₂ added (molar ratio 1:4). Simulated sunlight (AM 1.5G, 100 mW·cm⁻¹) was applied. -2Under irradiation, BiVO4 / CoO4 was deposited at a constant potential of 1.6 V vs. RHE for 30 min. After deposition, the mixture was rinsed with ultrapure water and dried with nitrogen to obtain BiVO4 / CoO4. x / VO2 photoanode.

[0059] The difference between this comparative example and Example 1 is that FeOOH cocatalyst was not used. This photoanode composite material consists of an FTO conductive glass substrate and a BiVO4 layer and CoO4 layer sequentially covering the FTO conductive glass substrate. x It consists of a layer and a VO2 layer.

[0060] The BiVO4 / CoO4 obtained in Example 1 x The performance of the / VO2 / FeOOH photoanode was tested, and the test results are as follows: (I) Structural Characterization 1. The BiVO4 and BiVO4 / CoO4 prepared in Example 1 x BiVO4 / CoO x / VO2 and BiVO4 / CoO x The / VO2 / FeOOH photoanode was analyzed by SEM, and the test results are detailed in [link to SEM analysis]. Figure 1 ,in, Figure 1 Figure a in the image is a SEM image of BiVO4. Figure 1 b in the figure represents BiVO4 / CoO x SEM image, Figure 1 c in the text represents BiVO4 / CoO x SEM image of / VO2, Figure 1 d in the figure represents BiVO4 / CoO x SEM image of / VO2 / FeOOH, by Figure 1 As can be seen from 'a', the BiVO4 film exhibits a worm-like nanoporous structure, which is caused by... Figure 1 From b and c in the equation, we can see that as CoO... x And VO2 deposition, BiVO4 / CoO x and BiVO4 / CoO x The surface of the / VO2 photoanode becomes rougher, and CoO can be clearly observed on the surface. x And VO2 nanoparticles. Figure 1 The d in the figure shows the uniform distribution of FeOOH, and no obvious aggregation was observed on the surface, indicating that the FeOOH layer is uniform.

[0061] (II) Performance Testing With an AM 1.5G xenon lamp light source, 100mW / cm² 2 Under light irradiation, the BiVO4 / CoO4 prepared in Example 1 was tested. x / VO2 / FeOOH photoanode composite material, BiVO4 substrate layer prepared in step (1) of Example 1, and BiVO4 / CoO2 prepared in Comparative Example 2. x Composite materials, BiVO4 / VO2 composite materials prepared in Comparative Example 3, and BiVO4 / CoO2 composite materials prepared in Comparative Example 4 x / VO2 composite material (hereinafter referred to as BiVO4 / CoO2 composite material) x / VO2, BiVO4, BiVO4 / CoO x The linear sweep voltammetric curves of BiVO4 / VO2 were obtained. All tests were conducted in a three-electrode system using the analyte as the working electrode, a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. The electrolyte was a 0.5 mol / L borate buffer solution with pH=9.3, and the scan rate was 10 mV / s. Specific test results are shown below. Figure 2 As shown: Figure 2 BiVO4 and BiVO4 / CoO4 under different applied bias voltages x BiVO4 / VO2 and BiVO4 / CoO x / VO2 electrode linear scan curve; from Figure 2 It can be seen that under an applied bias of 1.23 V vs. RHE, BiVO4 and BiVO4 / CoO x BiVO4 / VO2 and BiVO4 / CoO x The photocurrent densities of the / VO2 photoanode composite materials were 1.54, 3.0, 3.83, and 5.0 mA / cm², respectively. 2 .

[0062] Figure 3 In this context, 'a' represents BiVO4 or BiVO4 / CoO4. x BiVO4 / VO2 and BiVO4 / CoO x / VO2 photoanode under AM 1.5G simulated sunlight (100mW / cm²) 2 The cathode photocurrent delay curve measured under irradiation conditions of 0.4 V vs. RHE. Figure 3 In this context, 'b' represents the charge storage capacity under different applied bias voltages. From... Figure 3 As can be seen from 'a' in the figure, compared to pure BiVO4, BiVO4 / CoO x The "tailing" of the transient cathode current is more pronounced with BiVO4 / VO2 after illumination is turned off, indicating that CoO x Both the VO2 and VO2 layers can capture and store some photogenerated holes, from Figure 3 As can be seen from b, BiVO4 / CoO xBoth CoO4 and BiVO4 / VO2 have higher hole storage capacities than pure BiVO4, indicating that CoO4 has higher hole storage capacity. x Both VO2 and VO2 have a certain hole storage capacity, which can be achieved through their own redox active sites.

[0063] Figure 4 'a' in CoO x Cyclic voltammetry curves of the electrode releasing Co ions in their valence states during the oxygen evolution reaction. Figure 4 In the figure, b represents the cyclic voltammetry curve of the VO2 electrode during the oxygen evolution reaction, showing the valence state of V ions released. Figure 4 As can be seen from 'a' in CoO, x Its CV curve exhibits very significant redox peak characteristics, clearly indicating that Co element plays a crucial role in Co. 2+ Co 3+ Co 4+ Reversible redox reactions can occur between valence states. This reversible transition between multiple valence states is exemplified by CoO. x It provides key hole storage sites. From Figure 4 As can be seen from b in the figure, for VO2, there is a clear corresponding V in its CV curve. 4+ To V 5+ The oxidation peak of the transformed element appears in the potential range of approximately 0.9–1.6 V vs. RHE, while a corresponding reduction peak is also present during reverse scanning. This fully demonstrates the role of V in the transformation of RHE. 4+ and V 5+ It exhibits good reversible redox ability between valence states. CoO x VO2 stores holes by utilizing the valence changes of Co and V elements.

[0064] BiVO4, BiVO4 / CoO x BiVO4 / VO2 and BiVO4 / CoO x The SPV spectrum of the / VO2 photoanode is as follows: Figure 5 As shown. From Figure 5 It can be seen that all BiVO4-based photoanodes exhibit positive SPV signals, which, compared to the weak signals observed in BiVO4, indicate a significant increase in the signal intensity of the modified CoO4. x After VO2, BiVO4 / CoO x BiVO4 / VO2 photoanodes exhibit significantly enhanced surface photovoltage signals, while BiVO4 / CoO2 photoanodes... x The photovoltage signal on the surface of the / VO2 photoanode reached its highest value within the test wavelength range and maintained a high SPV level over a wide wavelength range (especially 300nm-500nm).

[0065] Figure 6BiVO4 / CoO x Hole storage mechanism of the / VO2 photoanode. Under illumination, holes migrate to CoO2. x And VO2 transfer. In the voltage range of 0.6-1.0V, Co... 2+ Transferred to CoO x Surface holes oxidize into Co 3+ To achieve hole storage, while Co 3+ The stored holes are released, oxidizing water to form O2, which is then reduced to Co. 2+ This enables the storage and release of holes. Similarly, within the voltage range of 0.9-1.6V, VO2 stores and releases holes through the redox couple of metallic V. Through the synergy of the two components, spatiotemporal hierarchical charge storage regulation is achieved.

[0066] BiVO4 / CoO4 under different applied bias voltages x / VO2 and BiVO4 / CoO x The electrode linear scan curve of / VO2 / FeOOH is shown below. Figure 7 As shown, from Figure 7 It can be seen from this that BiVO4 / CoO x / VO2 / FeOOH in 0.5 M KBi (pH=9.3) solution, AM 1.5G xenon lamp light source, 100mW / cm 2 Under light irradiation, with an applied bias voltage of 1.23 V vs. RHE, the photocurrent density is 6.22 mA / cm². 2 Under an applied bias voltage of 1.23V vs. RHE, the photocurrent density can be maintained at over 95% of its initial value after 23 hours of reaction; the photoelectric conversion efficiency (ABPE) under an applied bias voltage of 0.64V vs. RHE is 1.68%. The BiVO4 / CoO4... x The photocurrent density of the / VO2 photoanode is 5.0 mA / cm². -2 .

[0067] This invention provides a method based on BiVO4 / CoO x The artificial leaf device is made of BiVO4 / CoO2 / FeOOH photoanode composite material. x BiVO4 / FeOOH photoanode composite material, Pt wafer, and silicon solar cell integration. The silicon solar cell is placed on the side of the photoanode and connected in series with the working anode and cathode to power the anode and cathode, eliminating the need for an external voltage during application. BiVO4 / CoO2 in wired and wireless artificial leaves. x Detailed connection information for the / VO2 / FeOOH photoanode and Si PV panel is as follows: Figure 8As shown in a and b, the finished product of the wireless artificial leaf device is as follows: Figure 8 As shown in c and d, the prepared artificial leaf device is used in the decomposition of water to produce hydrogen and oxygen. Potassium borate solution is used as the electrolyte. The artificial leaf device is placed in the electrolyte, and photoelectrochemical water decomposition is performed under light irradiation. In this application, the concentration of the potassium borate solution is 0.5 mol / L; the light source is an AM 1.5G xenon lamp with an irradiance of 100 mW / cm². 2 . Figure 8 Figure 'e' shows the JV curve of the silicon photovoltaic cell, with a short-circuit current density (Jop) of 14.5 mA cm⁻¹. -2 The open-circuit voltage (Voc) is 1.15 V. Figure 8 Figure 'e' shows the JV curve of the silicon cell in a wired configuration with two electrodes. At a voltage of 1.11 V, the JV of the wired device... OP 7.12 mA cm -2 The STH conversion efficiency is 7.27%. Figure 8 f in the figure represents the linear BiVO4 / CoO4. x The photocurrent density-time curve of the / VO2 / FeOOH-PV artificial leaf shows that this wired artificial leaf can achieve water splitting for 5 hours with a photocurrent density retention rate as high as 86%. Figure 8 In this context, 'g' represents the wireless BiVO4 / CoO3 under AM 1.5G irradiation. x The corresponding H2 and O2 production curves of the / VO2 / FeOOH-PV artificial leaves show that after 1 hour of continuous illumination, the H2 / O2 production rate is 30.72 / 15.25 µmol / cm³. -2 The ratio is approximately 2:1.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A BiVO4 / CoO x / VO2 / FeOOH photoanode composite material, characterized in that... The system includes a transparent conductive substrate, a BiVO4 semiconductor light-absorbing material grown on the transparent conductive substrate, and a dual-hole storage layer with voltage-divided intervals covering the surface of the BiVO4 light-absorbing material, wherein the dual-hole storage layers with voltage-divided intervals are cobalt oxide and vanadium oxide, respectively; the BiVO4 / CoO x The / VO2 / FeOOH photoanode composite material has a layered structure, including a substrate, a BiVO4 layer, and a CoO layer with hole storage function. x The catalyst layer consists of VO2 and FeOOH, with x ranging from 1 to 2. The BiVO4 / CoO x The preparation method of / VO2 / FeOOH photoanode composite material includes the following steps: (1) A BiOI thin film was electrodeposited on the substrate surface. After adding acetylacetone vanadium oxide solution to the surface of the BiOI thin film, it was calcined at high temperature and soaked in alkaline solution to obtain a BiVO4 thin film substrate layer. (2) Using cobalt acetate aqueous solution as electrolyte, a three-electrode system was used to electrodeposit CoO on the surface of BiVO4 thin film at a constant potential. x Layers were prepared by controlling the deposition time to adjust the loading amount, followed by annealing to obtain BiVO4 / CoO4. x Photoanode; (3) In BiVO4 / CoO x On the photoanode surface, using a solution of V₂O₅ and H₂O₂ as a precursor, photoelectrochemical deposition was performed under simulated sunlight irradiation and a constant potential. By adjusting the deposition potential and time, the VO₂ layer was optimized to obtain BiVO₄ / CoO₂. x / VO2 photoanode; (4) In BiVO4 / CoO x On the surface of the / VO2 photoanode, using a nitrogen-protected FeSO4 aqueous solution as the electrolyte, photo-assisted electrodeposition was performed under simulated sunlight irradiation and constant potential. Three consecutive deposition cycles were carried out to finally obtain BiVO4 / CoO2. x / VO2 / FeOOH multilayer photoanodizing composite material.

2. The BiVO4 / CoO4 according to claim 1 x / VO2 / FeOOH photoanode composite material, characterized in that... The substrate mentioned in step (1) is a transparent conductive oxide material FTO glass. The substrate needs to be pretreated before use. The specific operation method is as follows: the substrate is ultrasonically cleaned with cleaning agent, acetone, ethanol and deionized water for 10 min to 15 min in sequence, and then soaked in ethanol for later use. The electrolyte for electrodeposition is obtained by mixing a potassium iodide solution of bismuth nitrate and a p-benzoquinone solution, wherein the concentration of bismuth nitrate in the potassium iodide solution is 0.03 mol / L to 0.05 mol / L, the concentration of potassium iodide is 0.3 mol / L to 0.5 mol / L, nitric acid is added to adjust the pH of the potassium iodide solution of bismuth nitrate to 1.5 to 2, the concentration of the p-benzoquinone solution is 0.18 mol / L to 0.28 mol / L, and the volume ratio of the potassium iodide solution of bismuth nitrate to the p-benzoquinone solution is 3 to 10: 1 to 5. The electrodeposition is performed in a three-electrode system, in which the substrate is the working electrode, the Ag / AgCl electrode is the reference electrode, and the Pt electrode is the counter electrode; the deposition potential is -0.05V to -0.15V vs. AgCl, and the electrodeposition time is 2 min to 5 min.

3. The BiVO4 / CoO4 according to claim 1 x / VO2 / FeOOH photoanode composite material, characterized in that... In step (1), vanadium acetylacetonate is dissolved in dimethyl sulfoxide to form a vanadium acetylacetonate solution with a concentration of 0.15 mol / L to 0.25 mol / L. The amount of vanadium acetylacetonate solution added based on the BiOI film is 50 μL / cm. 2 ~150μL / cm 2 ; The high-temperature calcination temperature is 400℃~500℃, and the high-temperature calcination time is 1h~3h. The alkaline solution used in the alkaline soaking is a sodium hydroxide solution with a concentration of 0.5mol / L~2mol / L. The alkaline solution soaking temperature is 20℃~30℃, and the soaking time is 1min~60min.

4. The BiVO4 / CoO4 according to claim 1 x / VO2 / FeOOH photoanode composite material, characterized in that... The electrolyte in step (2) is a 0.02 M to 0.03 M cobalt acetate aqueous solution; the deposition process is carried out using a three-electrode system under a constant potential of 0.25 V, and the deposition time is 20 s to 120 s; CoO x The deposition of the layer adopts a three-electrode system, in which the BiVO4 thin film is used as the working electrode, the platinum sheet is used as the counter electrode, and Ag / AgCl is used as the reference electrode; The electrolyte is 25×10 -3 M CH3COO2Co·4H2O aqueous solution; after deposition, the obtained film was annealed in air at 400℃~600℃ for 1h~3h to obtain BiVO4 / CoO x Photoanode; the annealing is performed in an air atmosphere.

5. The BiVO4 / CoO4 according to claim 1 x / VO2 / FeOOH photoanode composite material, characterized in that... The electrolyte in step (3) is a potassium tetraborate precursor solution containing vanadium pentoxide and hydrogen peroxide; the precursor solution is prepared by adding V2O5 powder to a potassium tetraborate aqueous solution and adding H2O2 to react and dissolve it to form a homogeneous solution. In the precursor solution, the concentration of V2O5 is 0.05 mol / L to 0.15 mol / L, the concentration of the potassium tetraborate aqueous solution is 0.2 mol / L to 0.8 mol / L, and the volume of H2O2 added is 1.0 mL to 2.0 mL for 100 mL of precursor solution. In step (3), BiVO4 / CoO x The thin film was used as the working electrode, the platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode; the deposition potential was adjusted to 1.2V~2.0V vs. RHE, and the deposition time was 15min~45min.

6. The BiVO4 / CoO4 according to claim 1 x / VO2 / FeOOH photoanode composite material, characterized in that... The electrolyte preparation process described in step (4) is as follows: FeSO4·7H2O is used as raw material. After deionized water is purged with nitrogen for 30 min, FeSO4·7H2O is added to prepare a FeSO4 solution with a concentration of 0.005 M~0.015 M. The electrodeposition is performed in a three-electrode system, wherein BiVO4 / CoO x The / VO2 thin film is used as the working electrode, the Ag / AgCl electrode is used as the reference electrode, and the Pt electrode is used as the counter electrode; the deposition potential of one deposition cycle is 0.05V~0.45V vs. Ag / AgCl, and the deposition time is 20min~40min; three deposition cycles are performed continuously; freshly prepared FeSO4·7H2O solution is used in each cycle; The light source used to simulate sunlight in step (4) is a 300 W xenon lamp with an AM 1.5G filter and a light intensity of 50 mW·cm. -2 ~150 mW·cm -2 And incident from the substrate side.

7. A BiVO4 / CoO4 according to claim 1 x The application of / VO2 / FeOOH photoanode composite material in the production of hydrogen and oxygen by water splitting is characterized by... BiVO4 / CoO x A three-electrode system is constructed using a VO2 / FeOOH photoanode composite material as the working electrode, a Pt sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. Potassium borate solution is used as the electrolyte, and photoelectrocatalytic water splitting is performed under light irradiation and an applied bias voltage. In this application, the concentration of the potassium borate solution is 0.1 mol / L to 1.0 mol / L, and the light source is an AM 1.5G xenon lamp with an irradiance of 10 mW / cm². 2 ~150mW / cm 2 The applied bias voltage is 1.23 V vs. RHE.

8. A method based on BiVO4 / CoO x The artificial leaf device made of / VO2 / FeOOH photoanode composite material is characterized by... The artificial leaf device is the BiVO4 / CoO4 described in claim 1. x The / VO2 / FeOOH photoanode composite material, Pt wafer, and silicon solar cell are integrated. The silicon solar cell is placed on the side of the photoanode and connected in series with the working anode and cathode to provide power to the anode and cathode, eliminating the need for an external voltage.

9. The application of the artificial leaf device according to claim 8 in the production of hydrogen and oxygen by water splitting, characterized in that, Potassium borate solution was used as the electrolyte. An artificial leaf device was placed in the electrolyte and subjected to photoelectrochemical water splitting under light irradiation. In this application, the concentration of the potassium borate solution was 0.1 mol / L to 1.0 mol / L, and the light source was an AM 1.5G xenon lamp with an irradiance of 10 mW / cm². 2 ~150mW / cm 2 .

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