BiVO4: Mo / Gd < 3 + > composite material as well as preparation method and application thereof

Abstract

The invention provides a BiVO4: Mo / Gd < 3 + > composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing a potassium iodide solution of Bi (NO3) 3, adjusting the pH value to 1.6-1.8, fully mixing the potassium iodide solution of Bi (NO3) 3 and a p-benzoquinone solution as a precursor solution, and carrying out constant-voltage deposition on the surface of FTO to obtain BiOI; respectively dropwise adding a mixed solution of a vanadium source and a molybdenum source, coating the mixed solution on the surface of BiOI, and calcining in a muffle furnace to prepare BiVO4: Mo; taking the BiVO4: Mo prepared in the step (2) as a matrix, soaking in a gadolinium nitrate hexahydrate solution, and drying to obtain the BiVO4: Mo / Gd < 3 + > composite material. The method is simple and economical, and the composite material is excellent in photoelectrocatalytic activity and has a good application prospect in the field of preparation of H2O2 through photoelectrocatalytic decomposition.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrocatalysis, and particularly relates to a BiVO4:Mo / Gd 3+ composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasing intensification of energy shortage, photoelectrocatalysis (PEC), as a green and efficient emerging energy conversion technology, has attracted much attention from researchers. As an important chemical reagent, H2O2 is widely used in industrial fields such as wastewater treatment, chemical synthesis, textile, and electronics industry, and is a zero-emission fuel that does not accelerate global warming. Most of the 95% of H2O2 on the market is produced by the anthraquinone oxidation method. However, traditional photoanode materials in photoelectrocatalysis such as BiVO4, TiO2, WO3, etc. have certain deficiencies in terms of photoelectrocatalytic performance and stability, which limit their Faraday efficiency in photoelectrocatalytic water splitting and the generation rate of H2O2. Therefore, it is urgent to explore photoelectrocatalysts with high selectivity and high activity.

[0003] As an n-type semiconductor oxide, BiVO4 has excellent photoelectrocatalytic performance due to its suitable valence band, conduction band positions, and light absorption characteristics, and is considered a promising photoanode material (Q. Zhang, M. Liu, W. Zhou, et al. Nano Energy 81 (2021) 105651.). However, BiVO4 also has problems such as poor water oxidation kinetics and serious photogenerated charge-hole recombination. Methods for improving the photoelectrocatalytic performance of BiVO4 include morphology optimization, doping, loading cocatalysts, and constructing heterojunctions, etc., and with the unremitting efforts of researchers, many achievements have been made. For example, the ZnO / BiVO4 heterojunction photoanode composite material prepared by the invention of patent CN 110373680 A has excellent photocatalytic performance and can quickly realize the separation and transport of photogenerated electron-hole pairs. However, it is still necessary to further explore BiVO4-based catalysts with excellent photocatalytic performance. Summary of the Invention

[0004] In order to overcome the disadvantages of existing catalyst materials, the present invention provides a BiVO4:Mo / Gd 3+ composite material, a preparation method thereof, and an application thereof.

[0005] The technical solution of the present invention is as follows:

[0006] A preparation method of a BiVO4:Mo / Gd 3+ composite material, comprising the following steps:

[0007] (1) Prepare a potassium iodide solution of Bi(NO3)3, adjust the pH to 1.6 - 1.8, and then fully mix the potassium iodide solution of Bi(NO3)3 with a p-benzoquinone solution as a precursor solution. Deposit BiOI on the FTO surface under a constant voltage.

[0008] (2) Dropwise add a mixed solution of a vanadium source and a molybdenum source onto the surface of BiOI, and place it in a muffle furnace for calcination to obtain BiVO4:Mo.

[0009] (3) Using BiVO4:Mo prepared in step (2) as a substrate, soak it in a gadolinium nitrate hexahydrate solution, and then dry it to obtain BiVO4:Mo / Gd 3+ Composite material.

[0010] In the above scheme, the molar concentration of the potassium iodide solution is 0.1M - 0.6M, the molar concentration of Bi(NO3)3 is 0.01M - 0.06M, and the volume ratio of the potassium iodide solution of Bi(NO3)3 to the p-benzoquinone solution is 10:1 - 1:10.

[0011] In the above scheme, the FTO is the FTO that has been ultrasonically treated with acetone, distilled water, and absolute ethanol for 5 - 30 minutes and then washed with deionized water.

[0012] In the above scheme, the constant voltage deposition conditions are as follows: using FTO as the working electrode, a Pt electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode, and performing electrodeposition using a three-electrode system; among them, the electrochemical workstation is CHI660E, the cathode potential is -0.5V - -0.1V, and the deposition time is 100 - 1000s.

[0013] In the above scheme, the mixed solution of the vanadium source and the molybdenum source is a mixed solution of a vanadyl acetylacetonate solution and a molybdenum acetylacetonate solution, both with a concentration of 0.1 - 1M, and the molar ratio is 99.9:0.1 - 0.1:99.9.

[0014] In the above scheme, for the calcination in the muffle furnace, the heating rate is 1 - 5°C / s, the heating temperature is 200 - 600°C, and the holding time is 1 - 4h.

[0015] The BiVO4:Mo / Gd 3+ The BiVO4:Mo / Gd composite material prepared by the preparation method of the composite material 3+ Composite material.

[0016] The BiVO4:Mo / Gd 3+ Composite material is applied in the photocatalytic decomposition of water to produce H2O2.

[0017] In the above scheme, the BiVO4:Mo / Gd 3+The composite material is used as a working electrode for photocatalytic water splitting to produce H2O2.

[0018] The beneficial effects of the present invention are as follows: The present invention provides BiVO4:Mo / Gd 3+ a preparation method of the composite material and its application in photocatalytic water splitting to produce hydrogen peroxide. By introducing Mo doping and using Gd 3+ as a co-catalyst to modify BiVO4, the water oxidation kinetics and the separation of photo-generated electrons and holes are promoted, and its photocatalytic performance is optimized. Description of the Drawings

[0019] Figure 1 Scanning electron microscope (SEM) image of the BiVO4:Mo / Gd 3+ composite material prepared in Example 1;

[0020] Figure 2 XRD diffraction pattern of the BiVO4:Mo / Gd 3+ composite material prepared in Example 1;

[0021] Figure 3 XPS full spectrum of the BiVO4:Mo / Gd 3+ composite material prepared in Example 1;

[0022] Figure 4 Transmission electron microscope image of the BiVO4:Mo / Gd 3+ composite material prepared in Example 1;

[0023] Figure 5 Faraday efficiency and H2O2 production rate diagram of the BiVO4:Mo / Gd 3+ composite material prepared in Example 1;

[0024] Figure 6 Stability test diagram of the BiVO4:Mo / Gd 3+ composite material when the current density is 20 mA / cm 2 ; Detailed Embodiments

[0025] In order to enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be described in detail below in conjunction with specific embodiments. However, the present invention is not limited to the following embodiments.

[0026] Before the synthesis reaction, the FTO used in the following examples was pretreated, uniformly cut into FTO with a size of 1.0 cm × 2.0 cm, and after ultrasonic treatment with acetone, absolute ethanol, and deionized water for 10 min, it was taken out and placed in absolute ethanol for standby.

[0027] Example 1

[0028] (1) Electrodeposition of BiIO / FTO

[0029] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a Bi(NO3)3 solution with a concentration of 0.04 mol·L -1 , and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a p-benzoquinone solution with a concentration of 0.23 mol·L -1 . Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them and stir to obtain the electroplating solution. Use FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, and carry out electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. Wash it with deionized water to remove the residual solution and impurities on the surface, and dry it for standby.

[0030] (2) Preparation of BiVO4:Mo

[0031] Drop 10 μL of a mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 99:5) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and put it into a muffle furnace. Heat it at a rate of 2 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak it in 1 M NaOH solution and wash it until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0032] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0033] Using BiVO4:Mo as the matrix, soak it in 0.025 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0034] Photoelectrochemical performance test

[0035] The test is carried out using a three-electrode system, and the electrolyte is 2 mol / L KHCO3 solution. Carry out the experiment of photocatalytic water splitting to prepare hydrogen peroxide under a xenon lamp with a light intensity of 100 mW·em- 2 , and calculate the hydrogen peroxide production and Faraday efficiency. Through chronopotentiometry at a constant current density of 20 mAcm- 2 for BiVO4:Mo / Gd3+ The composite material is subjected to a stability test.

[0036] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, scanning electron microscopy analysis is carried out, and the results are as Figure 1 shown. It can be seen that it is a nano-porous structure with uniform size and dense distribution.

[0037] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, X-ray diffraction analysis is carried out respectively, and the results are as Figure 2 shown. It can be seen that there are mainly diffraction peaks of FTO, BiVO4, Mo, and Gd, indicating that BiVO4:Mo / Gd 3+ the composite material is successfully prepared.

[0038] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, XPS full-spectrum analysis is carried out respectively, and the results are as Figure 3 shown. It can be seen that there are elements of Bi, O, V, Mo, and Gd, and the molar ratio of V to Mo is 95:5.

[0039] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, the transmission electron microscopy results are as Figure 4 shown. The lattice spacing is 0.4451 nm, corresponding to the (-121) crystal plane of BiVO4. For Gd 3+ modification, no lattice fringes are found.

[0040] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, the hydrogen peroxide generation rate and Faraday efficiency are as Figure 5 shown. The photoelectrocatalytic performance of the composite material is improved compared with that of pure bismuth vanadate.

[0041] For the BiVO4:Mo / Gd obtained in Example 1 of this 3+ composite material, the electrochemical stability test diagram is as Figure 6 shown. The results show that the stability is improved on the basis of pure bismuth vanadate.

[0042] Example 2

[0043] (1) Electrodeposit BiIO / FTO

[0044] Take 50 ml of 0.4 M KI solution as a solvent, add 0.97 g of Bi(NO3)3·5H2O, and make it 0.04 mol·L -1The Bi(NO3)3 solution was adjusted to pH 1.69 with concentrated nitric acid; 1.24 g of p-benzoquinone solid was dissolved in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1 p-benzoquinone solution. 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution were mixed, and after stirring, it was used as the electroplating solution. Using FTO as the working electrode, a Pt electrode as the auxiliary electrode, and an Ag / AgCl electrode as the reference electrode, electro-deposition was carried out using a three-electrode system. Among them, the electrochemical workstation was CHI660E, the cathode potential was -0.1 V vs AgCl, the deposition time was 600 s, and finally the BiOI / FTO electrode was deposited. After washing with deionized water to remove the residual solution and impurities on the surface, it was dried for standby.

[0045] (2) Preparation of BiVO4:Mo

[0046] 20 μL of a mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 95:5) was dropped onto the surface of the prepared BiOI / FTO electrode, and was evenly dropped on the BiOI surface respectively, and then placed in a muffle furnace, and heated at a rate of 2 °C·min -1 to 450 °C, kept for 2 h, then naturally cooled to room temperature and the sample was taken out, and then immersed and washed in 1 M NaOH solution until the surface of the sample was bright yellow, and BiVO4:Mo was prepared.

[0047] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0048] Using BiVO4:Mo as the matrix, it was immersed in a 0.015 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dried at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0049] Example 3

[0050] (1) Electro-deposition of BiIO / FTO

[0051] Taking 50 ml of 0.4 M KI solution as the solvent, adding 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjusting the pH to 1.69 with concentrated nitric acid; dissolving 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, stir to obtain the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, perform electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. After washing with deionized water to remove the residual solution and impurities on the surface, dry it for standby.

[0052] (2) Preparation of BiVO4:Mo

[0053] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 95:5) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace and heat it up at a rate of 2 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0054] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0055] Using BiVO4:Mo as the matrix, soak it in 0.035 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0056] Example 4

[0057] (1) Electrodeposition of BiIO / FTO

[0058] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, stir to obtain the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, perform electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. Wash it with deionized water to remove the residual solution and impurities on the surface, and dry it for standby.

[0059] (2) Preparation of BiVO4:Mo

[0060] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 95:5) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace. Heat it at a rate of 2 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0061] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0062] Using BiVO4:Mo as the matrix, soak it in 0.04 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0063] Example 5

[0064] (1) Electrodeposition of BiIO / FTO

[0065] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the prepared Bi(NO3)3 solution and 4.5 mL of the prepared p-benzoquinone solution and mix them. After stirring, it is used as the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, electro-deposition is carried out using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 1000 s, and finally the BiOI / FTO electrode is deposited. After washing with deionized water to remove the residual solution and impurities on the surface, it is dried for standby.

[0066] (2) Preparation of BiVO4:Mo

[0067] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 99:1) onto the surface of the prepared BiOI / FTO electrode, and evenly drop it on the BiOI surface respectively, then place it in a muffle furnace and heat it at a rate of 5 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0068] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0069] Using BiVO4:Mo as the matrix, soak it in 0.04 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0070] Example 6

[0071] (1) Electro-deposition of BiIO / FTO

[0072] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, stir, and use it as the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, perform electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. After washing with deionized water to remove the residual solution and impurities on the surface, dry it for standby.

[0073] (2) Preparation of BiVO4:Mo

[0074] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 90:10) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and put it into a muffle furnace, at a rate of 2 °C·min -1 Heat up to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0075] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0076] Using BiVO4:Mo as the matrix, soak it in 0.025 M gadolinium nitrate hexahydrate solution for 1 h respectively, and dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0077] Example 7

[0078] (1) Electrodeposition of BiIO / FTO

[0079] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, stir to obtain the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, carry out electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 1000 s, and finally the BiOI / FTO electrode is deposited. Wash it with deionized water to remove the residual solution and impurities on the surface, and dry it for standby.

[0080] (2) Preparation of BiVO4:Mo

[0081] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 99:1) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace, with a heating rate of 5 °C·min -1 Heat to 450 °C at a rate of, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0082] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0083] Using BiVO4:Mo as the matrix, soak it in 0.04 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0084] Example 8

[0085] (1) Electrodeposition of BiIO / FTO

[0086] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, stir, and use it as the electroplating solution. Using FTO as the working electrode, Pt electrode as the auxiliary electrode, and Ag / AgCl electrode as the reference electrode, perform electrodeposition using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.1 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. Wash it with deionized water to remove the residual solution and impurities on the surface, and dry it for standby.

[0087] (2) Preparation of BiVO4:Mo

[0088] Drop 10 μL of the mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 99:1) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace. Heat it at a rate of 5 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0089] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0090] Using BiVO4:Mo as the matrix, soak it in 0.03 M gadolinium nitrate hexahydrate solution for 1 h respectively, and dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0091] Example 9

[0092] (1) Electrodeposition of BiIO / FTO

[0093] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 13.0 mL of the above-prepared Bi(NO3)3 solution and 4.5 mL of the above-prepared p-benzoquinone solution, mix them, and stir to obtain the electroplating solution. Using FTO as the working electrode, a Pt electrode as the auxiliary electrode, and an Ag / AgCl electrode as the reference electrode, an electrodeposition is carried out using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.5 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. After washing with deionized water to remove the residual solution and impurities on the surface, it is dried for standby.

[0094] (2) Preparation of BiVO4:Mo

[0095] Drop 10 μL of a mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 93:7) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace. Heat it at a rate of 5 °C·min -1 to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak and wash it in 1 M NaOH solution until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0096] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0097] Using BiVO4:Mo as the matrix, soak it in a 0.025 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain the BiVO4:Mo / Gd 3+ Composite material.

[0098] Example 10

[0099] (1) Electrodeposition of BiIO / FTO

[0100] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a 0.04 mol·L -1 Bi(NO3)3 solution, and adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a 0.23 mol·L -1The p-benzoquinone solution. Take 26.0 mL of the above-prepared Bi(NO3)3 solution and 9 mL of the above-prepared p-benzoquinone solution, mix them, stir, and use it as the electroplating solution. Using FTO as the working electrode, a Pt electrode as the auxiliary electrode, and an Ag / AgCl electrode as the reference electrode, electro-deposition is carried out using a three-electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is -0.5 V vs AgCl, the deposition time is 600 s, and finally the BiOI / FTO electrode is deposited. After washing with deionized water to remove the residual solution and impurities on the surface, it is dried for standby.

[0101] (2) Preparation of BiVO4:Mo

[0102] Drop 10 μL of a mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 98:2) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace, at a rate of 5 °C·min -1 Heat up to 450 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample, and then soak it in 1 M NaOH solution to wash it until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0103] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0104] Using BiVO4:Mo as the matrix, soak it in 0.025 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 3 h to obtain BiVO4:Mo / Gd 3+ Composite material.

[0105] Example 11

[0106] (1) Electro-deposition of BiIO / FTO

[0107] Take 50 ml of 0.4 M KI solution as the solvent, add 0.97 g of Bi(NO3)3·5H2O to make a Bi(NO3)3 solution of 0.04 mol·L -1 Adjust the pH to 1.69 with concentrated nitric acid; dissolve 1.24 g of p-benzoquinone solid in 50 mL of absolute ethanol to prepare a p-benzoquinone solution of 0.23 mol·L -1p - benzoquinone solution. Take 13.0 mL of the above - prepared Bi(NO3)3 solution and 4.5 mL of the above - prepared p - benzoquinone solution, mix them, and use the mixture as the electroplating solution after stirring. Using FTO as the working electrode, a Pt electrode as the auxiliary electrode, and an Ag / AgCl electrode as the reference electrode, an electrodeposition is carried out using a three - electrode system. Among them, the electrochemical workstation is CHI660E, the cathode potential is - 0.5 V vs AgCl, the deposition time is 600 s, and finally a BiOI / FTO electrode is deposited. Wash it with deionized water to remove the residual solution and impurities on the surface, and dry it for standby.

[0108] (2) Preparation of BiVO4:Mo

[0109] Drop 10 μL of a mixed solution of 0.2 M vanadyl acetylacetonate and molybdenum acetylacetonate (molar ratio 94:6) onto the surface of the prepared BiOI / FTO electrode, evenly drop it on the BiOI surface respectively, and place it in a muffle furnace. Heat it at a rate of 2 °C·min -1 to 400 °C, keep it for 2 h, then naturally cool to room temperature and take out the sample. Then soak it in 1 M NaOH solution and wash it until the surface of the sample is bright yellow to obtain BiVO4:Mo.

[0110] (3) Preparation of BiVO4:Mo / Gd 3+ Composite material

[0111] Using BiVO4:Mo as the matrix, soak it in 0.05 M gadolinium nitrate hexahydrate solution for 1 h respectively, and then dry it at 80 °C for 2 h to obtain BiVO4:Mo / Gd 3+ Composite material.

Claims

1. A preparation method of BiVO4:Mo / Gd 3+ composite material, characterized in that: It includes the following steps: (1) Prepare a potassium iodide solution of Bi(NO3)3, adjust the pH to 1.6 - 1.8, and then fully mix the potassium iodide solution of Bi(NO3)3 with a p-benzoquinone solution as a precursor solution, and deposit BiOI on the FTO surface under a constant voltage; (2) Drop the mixed solution of vanadium source and molybdenum source onto the surface of BiOI respectively, and then place it in a muffle furnace for calcination to obtain BiVO4:Mo; (3) Using the BiVO4:Mo obtained in step (2) as the substrate, soak it in gadolinium nitrate hexahydrate solution, and then dry it to obtain BiVO4:Mo / Gd 3+ Composite material 2. The preparation method of the BiVO4:Mo / Gd 3+ composite material according to claim 1, characterized in that: The molar concentration of the potassium iodide solution is 0.1M - 0.6M, the molar concentration of Bi(NO3)3 is 0.01M - 0.06M, and the volume ratio of the potassium iodide solution of Bi(NO3)3 to the p-benzoquinone solution is 10:1 - 1:

10.

3. Preparation method of the BiVO4:Mo / Gd 3+ composite material according to Claim 1, characterized in that: The FTO is ultrasonically treated with acetone, distilled water, and absolute ethanol for 5 - 30 min respectively and then washed with deionized water.

4. The preparation method of the BiVO4:Mo / Gd 3+ composite material according to claim 1, characterized in that: The constant voltage deposition conditions are as follows: using FTO as the working electrode, a Pt electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode, and performing electrodeposition using a three-electrode system; among them, the electrochemical workstation is CHI660E, the cathode potential is -0.5 to -0.1V, and the deposition time is 100 - 1000s.

5. The preparation method of the BiVO4:Mo / Gd 3+ composite material according to claim 1, characterized in that: The mixed solution of the vanadium source and the molybdenum source is a mixed solution of vanadyl acetylacetonate solution and molybdenum acetylacetonate solution with a concentration of 0.1 - 1M each, and the molar ratio is 99.9:0.1 - 0.1:99.

9.

6. The preparation method of the BiVO4:Mo / Gd 3+ composite material, characterized in that: Put it into a muffle furnace for calcination, with a heating rate of 1 - 5°C / s, a heating temperature of 200 - 600°C, and a heat preservation duration of 1 - 4h.

7. BiVO4:Mo / Gd according to any one of claims 1 to 6 3+ BiVO4:Mo / Gd prepared by the preparation method of the composite material 3+ Composite material 8. BiVO4:Mo / Gd as claimed in claim 7 3+ Application of the composite material in photocatalytic water splitting for producing H2O2 9. The application according to claim 8, wherein: The BiVO4:Mo / Gd 3+ composite material is used as the working electrode for photocatalytic water splitting to produce H2O2.

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