Composite photoelectrocatalytic material, and preparation method therefor and use thereof

Abstract

The present invention belongs to the technical field of photoelectrocatalysis. Specifically disclosed are a composite photoelectrocatalytic material, and a preparation method therefor and a use thereof. According to the present invention, first, a Bi-containing solution is used as an electrolyte for electrodeposition, a V-containing precursor solution is coated, and then annealing treatment is performed to obtain a BiVO4 matrix material; then, the BiVO4 matrix material is used as a working electrode, a Ni-containing solution is used as an electrolyte, and photo-assisted electrodeposition is performed to obtain NiO / BiVO4; and then a solution containing Ni5P4 nanoparticles is coated on the NiO / BiVO4 to obtain the composite photoelectrocatalytic material. The composite photoelectrocatalytic material obtained according to the present invention has a built-in electric field, and has high catalytic activity and excellent catalytic performance; the Ni5P4 greatly improves the yield and selectivity of H2O2; and the preparation method also has the characteristics of simple operation, time saving, and low energy consumption.

Description

A composite photoelectrocatalytic material, its preparation method and application Technical Field

[0001] This invention relates to the field of photoelectrocatalysis technology, and in particular to a composite photoelectrocatalytic material, its preparation method, and its application. Background Technology

[0002] As human society continues to develop, the demand for fossil fuels continues to grow. However, the overuse of fossil fuels has led to serious environmental pollution problems, especially the large-scale emission of greenhouse gases such as carbon dioxide (CO2), ozone (O3), and methane (CH4). In order to achieve sustainable development, it is crucial to develop innovative technologies to control air pollution and mitigate greenhouse gas emissions, as well as to find new energy fuels to replace fossil fuels.

[0003] Photoelectrocatalysis (PEC), as an emerging technology, has shown great potential in controlling air pollution and mitigating greenhouse gas emissions. PEC technology converts light energy into chemical energy, promoting chemical reactions. In air pollution control, it can effectively degrade harmful gases in the air, such as nitrogen oxides and volatile organic compounds, converting them into harmless substances. Simultaneously, PEC technology can also convert greenhouse gases such as CO2 into useful chemicals, achieving greenhouse gas emission reduction and resource recycling.

[0004] Hydrogen peroxide, commonly known as hydrogen peroxide solution (H2O2), is the cleanest green oxidant. It has the highest active oxygen content (47.1% w / w) and produces no toxic byproducts during the reaction, only water (H2O) and oxygen (O2). Furthermore, H2O2 has an energy density of 3.0 MJ / L. -1 (60wt% H2O2) is higher than that of compressed hydrogen (35MPa, 2.8MJL). -1 H₂O₂ is a green, storable, and transportable fuel that can be directly used to generate electricity. Therefore, H₂O₂ is considered the most promising green energy carrier to replace fossil fuels. PEC (Polymerase Electron Oxidation) for H₂O₂ production is considered a green and economical method for synthesizing H₂O₂. However, because the water oxidation reaction (WOR) process is controlled by a four-electron reaction with slow kinetics, it results in the production of O₂, rather than the high-value-added H₂O₂. Therefore, the appropriate selection and rational design of semiconductor photocatalytic materials are of great significance for the efficient generation of H₂O₂ and for controlling air pollution and mitigating greenhouse gas emissions.

[0005] To date, among various semiconductor photocatalysts suitable for solar-driven H2O2 generation, such as titanium oxide (TiO2), tungsten oxide (WO3), and zinc oxide (ZnO), bismuth vanadate (BiVO4) stands out as a promising photocatalyst. BiVO4, with its monoclinic scheelite crystal system, possesses a narrow band gap of approximately 2.4 eV, enabling efficient absorption of sunlight and exhibiting a suitable band structure for selective H2O2 generation. Furthermore, the effective mass of photogenerated carriers in BiVO4 is significantly lighter than that of other oxides such as TiO2 and In2O3, making charge extraction easier. However, the performance of BiVO4 for solar-driven H2O2 generation is hampered by its inherent drawbacks, such as poor carrier mobility and charge separation efficiency. Additionally, the easy decomposition of H2O2 leads to typically low H2O2 yields from bare BiVO4.

[0006] Therefore, how to provide a composite photocatalytic material, design bare BiVO4, and optimize reaction conditions to improve the efficiency of BiVO4-based photocatalytic material in generating H2O2 under visible light is an urgent problem to be solved in this field. Summary of the Invention

[0007] In view of this, the present invention provides a composite photoelectrocatalytic material, its preparation method and application, to solve the problems of poor carrier mobility and charge separation efficiency, as well as low yield, when BiVO4 is used for solar H2O2 generation.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a composite photoelectrocatalytic material includes the following steps:

[0010] 1) Electrodeposition was performed using a Bi-containing solution as an electrolyte. After electrodeposition, a precursor solution containing V was coated and annealed to obtain a BiVO4 matrix material.

[0011] 2) Using BiVO4 matrix material as working electrode and Ni-containing solution as electrolyte, photo-assisted electrodeposition was performed to obtain NiO / BiVO4;

[0012] 3) A solution containing Ni5P4 nanoparticles was coated onto NiO / BiVO4 to obtain a Ni5P4 / NiO / BiVO4 composite photoelectrocatalytic material.

[0013] Preferably, the method for preparing the Bi-containing solution in step 1) includes: mixing potassium iodide, nitric acid, bismuth nitrate, and water to obtain a mixed solution, and then mixing the mixed solution with an ethanol solution of p-benzoquinone to obtain a Bi-containing solution.

[0014] The method for preparing the precursor solution containing V in step 1) includes: dissolving vanadium acetylacetonate in an organic solvent.

[0015] Preferably, the molar concentration of bismuth nitrate in the mixed solution is 0.03–0.05 mol / L;

[0016] The molar concentration of potassium iodide in the mixed solution is 0.3–0.5 mol / L;

[0017] The pH value of the mixed solution is 1.5 to 2;

[0018] The molar concentration of p-benzoquinone in the ethanol solution is 0.18–0.28 mol / L;

[0019] The volume ratio of the mixed solution to the ethanol solution of p-benzoquinone is 3-10:1-5;

[0020] The molar concentration of the precursor solution containing V is 0.18–0.22 mol / L.

[0021] Preferably, the electrodeposition conditions in step 1) are: electrodeposition for 180–240 s at a voltage of -0.1 V vs. Ag / AgCl;

[0022] The coating amount of the precursor solution containing V is 50–200 μL / cm. 2 .

[0023] Preferably, the nickel source for the Ni-containing solution in step 2) includes nickel sulfate;

[0024] The molar concentration of Ni in the Ni-containing solution is 0.02–0.03 mol / L;

[0025] The Ni-containing solution has a pH value of 6.5 to 7.5.

[0026] Preferably, the conditions for photo-assisted electrodeposition in step 2) are: at a voltage of 0.6V vs. SCE, the charge amount passing through the electrodeposition is in the range of 0.1–0.4 C / cm. 2 The auxiliary light source is a xenon lamp.

[0027] Preferably, the mass concentration of Ni5P4 nanoparticles in the solution containing Ni5P4 nanoparticles in step 3) is 1-10 mg / mL;

[0028] The Ni5P4 nanoparticles in the solution containing Ni5P4 nanoparticles have a particle size of 5–10 nm.

[0029] Preferably, the coating amount of the solution containing Ni5P4 nanoparticles in step 3) is 10–50 μL / cm. 2 .

[0030] Another object of the present invention is to provide a composite photocatalytic material prepared by the preparation method described above.

[0031] Another object of the present invention is to provide an application of a composite photoelectrocatalytic material in the preparation of H2O2 by PEC water oxidation.

[0032] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The photoelectrocatalytic material in this invention is a composite structure composed of three different materials. The heterojunction formed by BiVO4 and NiO causes a redistribution of charges at the interface, forming a strong built-in electric field at the interface, which is beneficial to improving catalytic activity and promoting the catalytic reaction. Furthermore, the surface-contact BiVO4 / NiO heterojunction can significantly shorten the charge transport distance and effectively increase the charge transport channels, thereby improving the catalytic effect to a certain extent.

[0034] 2. The preparation method of this invention combines coating and electrodeposition to produce Ni5P4 / NiO / BiVO4 photocatalytic materials with a composite structure. The electrodeposition and coating processes are relatively short, which improves the preparation efficiency of Ni5P4 / NiO / BiVO4 photocatalytic materials. It can be seen that the preparation method of this invention has the characteristics of simple operation, short time consumption and low energy consumption.

[0035] 3. In this invention, Ni5P4 is selected as a co-catalyst, which is inexpensive and greatly reduces costs. Furthermore, loading the Ni5P4 co-catalyst onto NiO / BiVO4 significantly improves the yield and selectivity of H2O2 production during the PEC water oxidation process.

[0036] 4. The Ni5P4 / NiO / BiVO4 photoelectrocatalyst material prepared by this invention not only passivates the interface states of Ni5P4 and BiVO4 by inserting a p-NiO layer between Ni5P4 and BiVO4, reducing the accumulation of holes, but also forms a pn junction with BiVO4. The built-in electric field formed promotes the transfer of holes from BiVO4 to Ni5P4, thereby improving the efficiency of PEC water oxidation reaction to generate H2O2.

[0037] 5. The Ni5P4 / NiO / BiVO4 photoelectrocatalyst material prepared by this invention exhibits excellent PEC performance in H2O2 generation. In a 2M KHCO3 electrolyte, it can reach 4.05 mA / cm² at a potential of 1.78 V vs. RHE. 2 It exhibits high photocurrent density and excellent stability.

[0038] 6. In addition, in order to simulate the practical application of PEC water oxidation to prepare H2O2, in a 2M KHCO3 electrolyte, the Ni5P4 / NiO / BiVO4 photoelectrocatalyst material prepared in this invention can achieve an H2O2 yield of 18.78 mol / h / cm2 with a potential of only 1.2V vs. RHE, showing excellent potential for PEC water oxidation to prepare H2O2. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 shows the SEM images of Ni5P4 / NiO / BiVO4, NiO / BiVO4 and BiVO4; where (a) in Figure 1 is the SEM image of BiVO4, (b) in Figure 1 is the SEM image of NiO / BiVO4 and (c) in Figure 1 is the SEM image of Ni5P4 / NiO / BiVO4.

[0041] Figure 2 shows TEM images of the Ni5P4 / NiO / BiVO4 photoelectrocatalyst material; in Figure 2(a), the transmission electron microscope image of Ni5P4 / NiO / BiVO4 is shown at a scale bar of 100 nm; and in Figure 2(b), the high-resolution transmission electron microscope image of Ni5P4 / NiO / BiVO4 is shown at a scale bar of 5 nm.

[0042] Figure 3 shows the linear sweep voltammetry curves of Ni5P4 / NiO / BiVO4, NiO / BiVO4, Ni5P4 / BiVO4, and BiVO4.

[0043] Figure 4 shows the real-time Faraday efficiency of H2O2 generation from Ni5P4 / NiO / BiVO4, NiO / BiVO4, and BiVO4 under different applied potentials. Detailed Implementation

[0044] This invention provides a method for preparing a composite photoelectrocatalytic material, comprising the following steps:

[0045] 1) Electrodeposition was performed using a Bi-containing solution as an electrolyte. After electrodeposition, a precursor solution containing V was coated and annealed to obtain a BiVO4 matrix material.

[0046] 2) Using BiVO4 matrix material as working electrode and Ni-containing solution as electrolyte, photo-assisted electrodeposition was performed to obtain NiO / BiVO4;

[0047] 3) A solution containing Ni5P4 nanoparticles was coated onto NiO / BiVO4 to obtain a Ni5P4 / NiO / BiVO4 composite photoelectrocatalytic material.

[0048] In this invention, the method for preparing the Bi-containing solution in step 1) includes: mixing potassium iodide, nitric acid, bismuth nitrate and water to obtain a mixed solution, and then mixing the mixed solution with an ethanol solution of p-benzoquinone to obtain a Bi-containing solution.

[0049] In this invention, the molar concentration of bismuth nitrate in the mixed solution is 0.03 to 0.05 mol / L, specifically 0.035 mol / L, 0.04 mol / L, or 0.045 mol / L, and more preferably 0.04 mol / L.

[0050] In this invention, the molar concentration of potassium iodide in the mixed solution is 0.3 to 0.5 mol / L, specifically 0.35 mol / L, 0.4 mol / L, or 0.45 mol / L, and more preferably 0.4 mol / L.

[0051] In this invention, the pH value of the mixed solution is 1.5 to 2, specifically 1.6, 1.7, 1.8, or 1.9.

[0052] In this invention, the molar concentration of p-benzoquinone in the ethanol solution is 0.18–0.28 mol / L, specifically 0.19 mol / L, 0.2 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L, 0.25 mol / L, or 0.26 mol / L, and more preferably 0.23 mol / L.

[0053] In this invention, the volume ratio of the mixed solution to the ethanol solution of p-benzoquinone is 3-10:1-5, preferably 4-9:2-4, more preferably 5-8:3, and even more preferably 6-7:3.

[0054] The molar ratio of bismuth nitrate in the mixed solution to p-benzoquinone in the ethanol solution is 0.03-0.05:0.18-0.28, preferably 0.035-0.045:0.2-0.25, and more preferably 0.04:0.22.

[0055] In this invention, the molar concentration of the precursor solution containing V is 0.18 to 0.22 mol / L, specifically 0.19 mol / L, 0.2 mol / L, or 0.21 mol / L.

[0056] In this invention, the electrodeposition conditions in step 1) are: electrodeposition for 180 to 240 s at a voltage of -0.1 V vs. Ag / AgCl, and the specific deposition time can be 185 s, 190 s, 195 s, 200 s, 210 s, 220 s, or 230 s.

[0057] In this invention, the coating amount of the precursor solution containing V is 50–200 μL / cm. 2 Specifically, it can be 60 μL / cm 2 80μL / cm 2 100μL / cm 2 120μL / cm 2 150μL / cm 2 180μL / cm 2 .

[0058] In this invention, the annealing treatment in step 1) is a conventional annealing treatment. The annealing temperature is preferably 400-500℃, specifically 420℃, 450℃, or 480℃. The annealing time is preferably 1.5-2.5h, specifically 1.6h, 1.8h, 2h, 2.2h, or 2.4h.

[0059] In this invention, the electrodeposition in step 1) uses an FTO substrate, a platinum wire, and an Ag / AgCl electrode as the working electrode, counter electrode, and reference electrode, respectively. First, a BiOI electrode is deposited on the FTO substrate, and then a V-containing precursor solution is coated as a V source. After annealing, BiVO4 is generated, and the BiVO4 matrix material is grown on the FTO substrate.

[0060] In this invention, the nickel source of the Ni-containing solution in step 2) includes nickel sulfate.

[0061] In this invention, the molar concentration of Ni in the Ni-containing solution is 0.02 to 0.03 mol / L, specifically 0.22 mol / L, 0.24 mol / L, 0.25 mol / L, 0.26 mol / L, or 0.28 mol / L.

[0062] In this invention, the pH value of the Ni-containing solution is 6.5 to 7.5, specifically 6.6, 6.8, 7, 7.2, or 7.4.

[0063] In this invention, the conditions for photo-assisted electrodeposition in step 2) are: at a voltage of 0.6V vs. SCE, the charge amount passing through the electrodeposition ranges from 0.1 to 0.4 C / cm. 2 Specifically, it can be 0.15C / cm 2 0.2C / cm 20.25C / cm 2 0.3C / cm 2 0.35C / cm 2 The auxiliary light source is a xenon lamp.

[0064] In this invention, the photo-assisted electrodeposition in step 2) uses BiVO4 substrate material, platinum wire and saturated calomel electrode as working electrode, counter electrode and reference electrode respectively.

[0065] In this invention, the mass concentration of Ni5P4 nanoparticles in the solution containing Ni5P4 nanoparticles in step 3) is 1 to 10 mg / mL, specifically 2 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, or 8 mg / mL.

[0066] In this invention, the particle size of the Ni5P4 nanoparticles in the solution containing Ni5P4 nanoparticles is 5-10 nm, specifically 6 nm, 7 nm, 8 nm, or 9 nm.

[0067] In this invention, the coating in step 3) is preferably spin coating, and the spin coating speed is preferably 1500-4500 rpm, specifically 1800 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, or 4000 rpm; the spin coating time is preferably 30 s.

[0068] In this invention, the coating amount of the solution containing Ni5P4 nanoparticles in step 3) is 10–50 μL / cm. 2 Specifically, it can be 15 μL / cm 2 20μL / cm 2 25μL / cm 2 30μL / cm 2 35μL / cm 2 40μL / cm 2 45μL / cm 2 .

[0069] In this invention, step 2) photo-assisted electrodeposition and step 3) coating with a solution containing Ni5P4 nanoparticles independently include an annealing treatment. The annealing temperature is preferably 280–320°C, specifically 290°C, 300°C, or 310°C; the annealing time is preferably 15–45 min, specifically 20 min, 25 min, 30 min, 35 min, or 40 min.

[0070] The present invention also provides a composite photocatalytic material prepared by the above preparation method.

[0071] This invention also provides an application of a composite photoelectrocatalytic material in the preparation of H2O2 by PEC water oxidation.

[0072] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Example 1

[0074] A method for preparing a Ni5P4 / NiO / BiVO4 photoelectrocatalytic material includes the following steps:

[0075] Step 1: Clean the FTO (1cm×2cm) with detergent, acetone, ethanol and deionized water for 10 minutes respectively. Use it as an FTO substrate and immerse it in ethanol for later use.

[0076] Step 2: Dissolve KI (potassium iodide) in 50 mL of deionized water, add HNO3 (nitric acid) to adjust the pH of the solution, then add Bi(NO3)3 (bismuth nitrate), and stir thoroughly for 10 min to form mixed solution I (KI molar concentration is 0.4 mol / L, Bi(NO3)3 molar concentration is 0.04 mol / L, pH is 1.7); subsequently, mix 20 mL of 0.23 mol / L p-benzoquinone ethanol solution with solution I to form mixed solution II;

[0077] Step 3: Using the mixed solution II from Step 2 as the electrolyte, and using the FTO substrate, platinum wire, and Ag / AgCl electrode obtained in Step 1 as the working electrode, counter electrode, and reference electrode, respectively, BiVO4 matrix material is prepared by electrodeposition using a three-electrode system. The electrodeposition conditions are: electrodeposition for 200s at a voltage of -0.1V vs. Ag / AgCl; after electrodeposition, the BiIO matrix material obtained by electrodeposition is rinsed several times with deionized water and ethanol, and then naturally dried in air; before annealing, 150μL of 0.2mol / L vanadium acetylacetonate / dimethyl sulfoxide solution is pipetted onto the BiIO matrix material and then annealed in air at 450℃ for 2h to obtain the BiVO4 matrix material.

[0078] Step 4: Dissolve NiSO4·6H2O (nickel sulfate) in 70 mL of deionized water to obtain a nickel sulfate aqueous solution with a molar concentration of 0.025 mol / L. Then, add 2 mol / L NaOH (sodium hydroxide) to adjust the pH of the solution to 7, forming mixed solution III. Using mixed solution III as the electrolyte, the BiVO4 matrix material from step 3 and the platinum wire and saturated calomel (SCE) electrode are used as the working electrode, counter electrode, and reference electrode, respectively. NiO / BiVO4 is prepared by photo-assisted electrodeposition using a three-electrode system. The photoelectrodeposition conditions are: under xenon lamp assisted illumination, electrodeposition at a voltage of 0.6 V vs. SCE is equivalent to passing through 0.2 C / cm 2 The total charge; after photo-assisted electrodeposition, the obtained NiO / BiVO4 was rinsed several times with deionized water and ethanol, then naturally dried in air, and finally annealed at 300℃ for 30 min in N2 atmosphere;

[0079] Step 5: Take 50 μL of a 5 mg / mL Ni5P4 solution (Ni5P4 particle size 5–10 nm) as the precursor solution and spin-coat it onto the NiO / BiVO4 from Step 4. The spin-coating conditions are: 3000 rpm, 30 s; after spin-coating, anneal in air at 300 °C for 30 min to obtain the Ni5P4 / NiO / BiVO4 composite photoelectrocatalyst material.

[0080] Structural characterization

[0081] The Ni5P4 / NiO / BiVO4, NiO / BiVO4, and BiVO4 prepared in Example 1 were analyzed by SEM, and the results are detailed in Figure 1. Figure 1(a) shows the SEM image of BiVO4, Figure 1(b) shows the SEM image of NiO / BiVO4, and Figure 1(c) shows the SEM image of Ni5P4 / NiO / BiVO4. As can be seen from Figure 1, BiVO4 exhibits a smooth, worm-like structure. Compared to BiVO4, NiO / BiVO4 shows a coarser worm-like structure with a rougher surface, indicating the presence of NiO. Although Ni5P4 / NiO / BiVO4 shows a similar morphology to NiO / BiVO4, this can be attributed to the smaller size of the Ni5P4 particles.

[0082] The morphology of the Ni5P4 / NiO / BiVO4 photoelectrocatalyst material prepared in Example 1 was observed using high-resolution transmission electron microscopy (HRTEM), and the results are detailed in Figure 2. Figure 2(a) shows the HRTEM image of Ni5P4 / NiO / BiVO4 at a scale bar of 100 nm; Figure 2(b) shows the HRTEM image of Ni5P4 / NiO / BiVO4 at a scale bar of 5 nm. Figure 2(b) shows that the BiVO4 surface is covered with a layer of NiO, and Ni5P4 nanoparticles are attached to the NiO surface. The measured lattice fringe value is 0.401 nm, corresponding to the (102) crystal plane of Ni5P4.

[0083] Performance testing

[0084] Linear sweep voltammetry tests were performed on Ni5P4 / NiO / BiVO4, NiO / BiVO4, BiVO4, and Ni5P4 / BiVO4 obtained in Example 1 (the preparation method differed from Example 1 only in that the photo-assisted electrodeposition step of NiO was omitted). The test conditions were as follows: the electrolyte used was 2MKHCO3, the voltage window was 0.3–1.3 V (vs. Ag / AgCl), and the scan rate was 10 mV / s. -1 The linear sweep voltammetry curves obtained from the tests are shown in Figure 3. Figure 3 shows that at a voltage of 1.78V vs. RHE, Ni5P4 / NiO / BiVO4 exhibits the highest photocurrent density (4.05 mA cm⁻¹). -2 The photocurrent of Ni5P4 / BiVO4 is 2.7 mA cm⁻¹. -2 In comparison, it can be found that the insertion of NiO helps to improve the performance of PEC generated by H2O2.

[0085] The real-time Faradaic efficiency (FE) of H2O2 generation obtained from Example 1 for Ni5P4 / NiO / BiVO4, NiO / BiVO4, and BiVO4 under different applied potentials was tested. The test conditions were as follows: the electrolyte used was 2M KHCO3, the voltage window was -0.1 to 1.5V (vs. Ag / AgCl), and the test time was 10 min. The real-time Faradaic efficiency (FE) of H2O2 generation under different applied potentials is shown in Figure 4. As can be seen from Figure 4, Ni5P4 / NiO / BiVO4 exhibited the highest Faradaic efficiency (FE) of H2O2 generation under different voltages, which was significantly improved compared to NiO / BiVO4 and BiVO4. This indicates that the loading of Ni5P4 cocatalyst is beneficial to improving the selectivity for H2O2 during the PEC water oxidation process.

[0086] Example 2

[0087] A method for preparing a Ni5P4 / NiO / BiVO4 photoelectrocatalytic material includes the following steps:

[0088] Step 1: Clean the FTO (1cm×2cm) with detergent, acetone, ethanol and deionized water for 15 minutes respectively. Use it as an FTO substrate and immerse it in ethanol for later use.

[0089] Step 2: Dissolve KI (potassium iodide) in 50 mL of deionized water, add HNO3 (nitric acid) to adjust the pH of the solution, then add Bi(NO3)3 (bismuth nitrate), and stir thoroughly for 10 min to form mixed solution I (KI molar concentration is 0.4 mol / L, Bi(NO3)3 molar concentration is 0.04 mol / L, pH is 1.7); subsequently, mix 20 mL of 0.23 mol / L p-benzoquinone ethanol solution with solution I to form mixed solution II;

[0090] Step 3: Using the mixed solution II from Step 2 as the electrolyte, and using the FTO substrate, platinum wire, and Ag / AgCl electrode obtained in Step 1 as the working electrode, counter electrode, and reference electrode, respectively, a BiVO4 matrix material was prepared by electrodeposition using a three-electrode system. The electrodeposition conditions were: electrodeposition for 240 s at a voltage of -0.1 V vs. Ag / AgCl; after electrodeposition, the BiIO matrix material obtained by electrodeposition was rinsed several times with deionized water and ethanol, and then air-dried naturally; before annealing, 150 μL of a 0.2 mol / L vanadium acetylacetonate / dimethyl sulfoxide solution was pipetted onto the BiIO matrix material and then annealed in air at 450 °C for 2 h to obtain the BiVO4 matrix material.

[0091] Step 4: Dissolve NiSO4·6H2O (nickel sulfate) in 70 mL of deionized water to obtain a nickel sulfate aqueous solution with a molar concentration of 0.025 mol / L. Then, add 2 mol / L NaOH (sodium hydroxide) to adjust the pH of the solution to 7, forming mixed solution III. Using mixed solution III as the electrolyte, the BiVO4 matrix material from step 3 and the platinum wire and saturated calomel (SCE) electrode are used as the working electrode, counter electrode, and reference electrode, respectively. NiO / BiVO4 is prepared by photo-assisted electrodeposition using a three-electrode system. The photoelectrodeposition conditions are: under xenon lamp assisted illumination, electrodeposition at a voltage of 0.6 V vs. SCE is equivalent to passing through 0.4 C / cm 2 The total charge; after photo-assisted electrodeposition, the obtained NiO / BiVO4 was rinsed several times with deionized water and ethanol, then naturally dried in air, and finally annealed at 300℃ for 30 min in N2 atmosphere;

[0092] Step 5: Take 50 μL of a 5 mg / mL Ni5P4 solution (Ni5P4 particle size 5–10 nm) as the precursor solution and spin-coat it onto the NiO / BiVO4 from Step 4. The spin-coating conditions are: 4500 rpm, 30 s; after spin-coating, anneal in air at 300 °C for 30 min to obtain the Ni5P4 / NiO / BiVO4 composite photoelectrocatalyst material.

[0093] Example 3

[0094] A method for preparing a Ni5P4 / NiO / BiVO4 photoelectrocatalytic material includes the following steps:

[0095] Step 1: Clean the FTO (1cm×2cm) with detergent, acetone, ethanol and deionized water for 10 minutes respectively. Use it as an FTO substrate and immerse it in ethanol for later use.

[0096] Step 2: Dissolve KI (potassium iodide) in 50 mL of deionized water, add HNO3 (nitric acid) to adjust the pH of the solution, then add Bi(NO3)3 (bismuth nitrate), and stir thoroughly for 10 min to form mixed solution I (KI molar concentration is 0.3 mol / L, Bi(NO3)3 molar concentration is 0.03 mol / L, pH is 2); subsequently, mix 20 mL of 0.2 mol / L p-benzoquinone ethanol solution with solution I to form mixed solution II;

[0097] Step 3: Using the mixed solution II from Step 2 as the electrolyte, and using the FTO substrate, platinum wire, and Ag / AgCl electrode obtained in Step 1 as the working electrode, counter electrode, and reference electrode, respectively, a BiVO4 matrix material is prepared by electrodeposition using a three-electrode system. The electrodeposition conditions are: electrodeposition for 180 s at a voltage of -0.1 V vs. Ag / AgCl; after electrodeposition, the BiIO matrix material obtained by electrodeposition is rinsed several times with deionized water and ethanol, and then air-dried naturally; before annealing, 150 μL of a 0.2 mol / L vanadium acetylacetonate / dimethyl sulfoxide solution is pipetted onto the BiIO matrix material and then annealed in air at 450 °C for 2 h to obtain the BiVO4 matrix material.

[0098] Step 4: Dissolve NiSO4·6H2O (nickel sulfate) in 70 mL of deionized water to obtain a nickel sulfate aqueous solution with a molar concentration of 0.02 mol / L. Then, add 2 mol / L NaOH (sodium hydroxide) to adjust the pH of the solution to 6.5, forming mixed solution III. Using mixed solution III as the electrolyte, the BiVO4 matrix material from step 3 and the platinum wire and saturated calomel (SCE) electrode are used as the working electrode, counter electrode, and reference electrode, respectively. NiO / BiVO4 is prepared by photo-assisted electrodeposition using a three-electrode system. The photoelectrodeposition conditions are: under xenon lamp assisted illumination, electrodeposition at a voltage of 0.6 V vs. SCE is equivalent to passing through 0.3 C / cm 2 The total charge; after photo-assisted electrodeposition, the obtained NiO / BiVO4 was rinsed several times with deionized water and ethanol, then naturally dried in air, and finally annealed at 300℃ for 30 min in N2 atmosphere;

[0099] Step 5: Take 50 μL of a Ni5P4 solution with a concentration of 8 mg / mL (Ni5P4 particle size of 8-10 nm) as the precursor solution and spin-coat it onto the NiO / BiVO4 from Step 4. The spin-coating conditions are: 3000 rpm, 30 s; after spin-coating, anneal in air at 300℃ for 30 min to obtain the Ni5P4 / NiO / BiVO4 composite photoelectrocatalyst material.

[0100] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0101] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a composite photoelectrocatalytic material, characterized in that, The method comprises the following steps: 1) electrodepositing a Bi-containing solution as an electrolyte, coating a V-containing precursor solution after the electrodepositing, and obtaining a BiVO4 matrix material through annealing treatment; 2) performing photo-assisted electrodeposition by taking the BiVO4 matrix material as a working electrode and a Ni-containing solution as an electrolyte, and obtaining NiO / BiVO4; 3) coating a Ni5P4 nanoparticle-containing solution on the NiO / BiVO4 to obtain a Ni5P4 / NiO / BiVO4 composite photoelectrocatalytic material.

2. The method for preparing a composite photoelectrocatalytic material according to claim 1, characterized in that, The preparation method of the Bi-containing solution in step 1) comprises the following steps: mixing potassium iodide, nitric acid, bismuth nitrate and water to obtain a mixed solution, and then mixing the mixed solution with an ethanol solution of p-benzoquinone to obtain the Bi-containing solution. The preparation method of the V-containing precursor solution in step 1) comprises the following steps: dissolving vanadium acetylacetonate in an organic solvent.

3. The method for preparing a composite photoelectrocatalytic material according to claim 2, characterized in that, The molar concentration of bismuth nitrate in the mixed solution is 0.03-0.05 mol / L. The molar concentration of potassium iodide in the mixed solution is 0.3-0.5 mol / L. The pH value of the mixed solution is 1.5-2. The molar concentration of p-benzoquinone in the ethanol solution of p-benzoquinone is 0.18-0.28 mol / L. The volume ratio of the mixed solution to the ethanol solution of p-benzoquinone is 3-10:1-5. The molar concentration of the V-containing precursor solution is 0.18-0.22 mol / L.

4. The preparation method of the composite photoelectrocatalytic material according to any one of claims 1-3, characterized in that, The electrodeposition condition in step 1) is that the electrodeposition is performed at a voltage of-0.1 V vs.Ag / AgCl for 180-240 s. The coating amount of the V-containing precursor solution is 50 to 200 μL / cm 2 .

5. The method for preparing a composite photoelectrocatalytic material according to claim 4, characterized in that, The nickel source of the Ni-containing solution in step 2) comprises nickel sulfate. The molar concentration of Ni in the Ni-containing solution is 0.02-0.03 mol / L. The pH value of the Ni-containing solution is 6.5-7.

5.

6. The method for preparing a composite photoelectrocatalytic material according to claim 5, characterized in that, The conditions for the photo-assisted electrodeposition in step 2) are: the amount of charge passed for the electrodeposition ranges from 0.1 to 0.4 C / cm2at a voltage of 0.6 V vs. SCE 2 ; the auxiliary light source is a xenon lamp.

7. The method for preparing a composite photoelectrocatalytic material according to claim 5 or 6, characterized in that, The mass concentration of Ni5P4 nanoparticles in the Ni5P4 nanoparticle-containing solution in step 3) is 1-10 mg / mL. The particle size of the Ni5P4 nanoparticles in the Ni5P4 nanoparticle-containing solution is 5-10 nm. 8.The method of claim 7, wherein the method further comprises the step of: The coating amount of the solution containing Ni5P4 nanoparticles in Step 3) is 10 to 50 μL / cm 2 . ​ 9. The composite photoelectrocatalytic material prepared by the preparation method in any one of claims 1-8.

10. The application of the composite photoelectrocatalytic material in claim 9 in PEC water oxidation for preparing H2O2.

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