A method for preparing a BiVO4 / CuFe2O4 composite photoanode and its application
By loading CuFe2O4 nanoparticles onto the surface of BiVO4 to form a heterostructure, the problems of charge recombination and slow water oxidation kinetics in BiVO4 photoelectrodes were solved, and highly efficient photoelectrocatalytic water splitting performance was achieved.
Patent Information
- Application Number
- CN202510096535.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-12
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2045-01-12
AI Technical Summary
The BiVO4 photoelectrode suffers from severe charge recombination and slow water oxidation kinetics, limiting its potential for practical application in photoelectrochemical water splitting.
BiVO4/CuFe2O4 composite photoanodes were prepared by loading CuFe2O4 nanoparticles onto the surface of BiVO4 to form a heterostructure, which promoted the separation and transport of photogenerated electrons and holes and suppressed charge recombination.
It increases photocurrent density, enhances charge transfer and separation, prolongs the lifetime of photogenerated carriers, and improves water oxidation kinetics and electrode stability.
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Figure CN119913559B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photoelectrocatalysis technology, specifically relating to the preparation method of BiVO4 / CuFe2O4 composite photoelectrode and its application in photoelectrocatalytic water splitting. Background Technology
[0002] Photoelectrochemical water splitting for hydrogen production is a clean energy technology. Its basic principle is to use light energy to activate a catalyst, which, under the influence of an external circuit, promotes the decomposition of water molecules to produce hydrogen and oxygen. This technology has the potential to convert solar energy into chemical energy and is considered a sustainable energy solution for the future. Therefore, developing efficient photoelectrochemical water splitting technology is of great significance for reducing dependence on fossil fuels and lowering greenhouse gas emissions. Among numerous photoanode materials, bismuth vanadate (BiVO4) has attracted widespread attention due to its high theoretical photocurrent density and conversion efficiency. However, due to the poor charge transport characteristics of the BiVO4 photoelectrode (carrier mobility of 0.044 cm⁻¹), it has been difficult to produce hydrogen. 2 V -1 s -1 The short hole diffusion length (<70 nm) leads to severe charge recombination and slow water oxidation kinetics, which greatly limits its potential for practical applications.
[0003] Heteroatom doping, structural construction, crystal plane engineering, heterostructure building, defect engineering, and supported oxygen evolution co-catalysts (OECs) are considered effective strategies to improve the water oxidation activity of BiVO4 photoelectrodes in photoelectrochemical processes (PECs). It should be noted that the oxygen evolution reaction (OER) is a complex four-electron transfer process, and modifying the BiVO4 surface with appropriate OECs is crucial for suppressing surface charge recombination. However, modifying the BiVO4 surface with highly active OECs does not always achieve high photoelectrocatalytic performance because the driving force at the OEC / BiVO4 interface is relatively weak, failing to extract all photogenerated holes from BiVO4 for OER in a timely manner. Therefore, there is an urgent need to develop a highly efficient photoelectrocatalytic material that suppresses charge recombination at the OEC / BiVO4 interface for photoelectrochemical water splitting. Summary of the Invention
[0004] To address the problems of severe charge recombination and slow water oxidation kinetics in BiVO4 photoelectrodes, this invention provides a method for preparing a BiVO4 / CuFe2O4 composite photoanode for efficient photoelectrocatalytic water splitting.
[0005] The technical solution of the present invention is as follows:
[0006] This invention provides a method for preparing a BiVO4 / CuFe2O4 composite photoanode, the preparation steps of which include:
[0007] S1: A three-electrode system was constructed using FTO conductive glass as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. An aqueous solution containing bismuth nitrate and potassium iodide was mixed with an ethanol solution containing p-benzoquinone as the electrolyte. The mixture was deposited at a certain potential, and the resulting electrode was denoted as BiOI.
[0008] S2: A dimethyl sulfoxide solution containing vanadium acetylacetonate was drop-coated onto the BiOI electrode, then placed in a muffle furnace for calcination. After cooling to room temperature, it was immersed in NaOH solution for 20-30 minutes. The product after removal, washing and drying was denoted as BiVO4.
[0009] S3: Heat an aqueous solution containing copper nitrate, ferric nitrate and citric acid in a drying oven to 50-100°C and maintain for 10-12 hours. After cooling to room temperature, grind the resulting substance into powder and then calcine it in a muffle furnace. The powder obtained after grinding is denoted as CuFe2O4.
[0010] S4: Dissolve the CuFe2O4 powder in anhydrous ethanol, drop-coat it onto the BiVO4 electrode, and then calcine it in a muffle furnace. The resulting electrode is denoted as BiVO4 / CuFe2O4.
[0011] Furthermore, the concentration of bismuth nitrate in the S1 aqueous solution is 0.04–0.06 mol / L, the concentration of potassium iodide is 0.04–0.06 mol / L, the concentration of p-benzoquinone solution is 0.2–0.3 mol / L, the volume ratio of aqueous solution to ethanol solution is 5:2, the deposition potential is -0.1 ± 0.05 V vs. Ag / AgCl, and the deposition time is 400–500 s.
[0012] Preferably, the concentration of bismuth nitrate is 0.05 mol / L, the concentration of potassium iodide is 0.05 mol / L, the concentration of p-benzoquinone solution is 0.23 mol / L, the deposition potential is -0.1 V vs. Ag / AgCl, and the deposition time is 400 s.
[0013] Furthermore, the concentration of vanadium acetylacetonate in S2 is 0.1–0.3 mol / L, the calcination temperature in the muffle furnace is 400–500℃, the heating rate is 1–3℃ / min, and the holding time is 0.5–1.5 h.
[0014] Preferably, the concentration of acetylacetone vanadium oxide is 0.2 mol / L, the calcination temperature in the muffle furnace is 450℃, the heating rate is 2℃ / min, and the holding time is 1h.
[0015] Furthermore, in S3, copper nitrate, ferric nitrate, and citric acid are mixed in a molar ratio of 1:2:3, and calcined in a muffle furnace at a temperature of 400–500°C, a heating rate of 3–5°C / min, and a holding time of 4–6 h.
[0016] Preferably, the calcination temperature in the muffle furnace is 500℃, the heating rate is 4℃ / min, and the holding time is 5h.
[0017] Furthermore, the concentration of CuFe2O4 solution in S4 is 0.05–0.15 mol / L, the calcination temperature in the muffle furnace is 150–200 °C, the heating rate is 5–10 °C / min, and the holding time is 0.5–1.5 h.
[0018] Preferably, the CuFe2O4 solution concentration is 0.10 mol / L, and the calcination temperature in the muffle furnace is 180℃.
[0019] Based on the same inventive concept, this invention also provides a method for preparing a BiVO4 / CuFe2O4 composite photoanode and its application.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] (1) In this invention, CuFe2O4 powder is combined with BiVO4 electrode by drop coating and heat treatment. The synthesis method is simple and the raw materials are widely available.
[0022] (2) The CuFe2O4 nanoparticles prepared in this invention can form a heterostructure with BiVO4. Under sunlight irradiation, both CuFe2O4 and BiVO4 will generate electron-hole pairs. Due to the heterostructure formed by CuFe2O4 and BiVO4, photogenerated electrons can easily move from the conduction band of CuFe2O4 to the conduction band of BiVO4 and be collected on the FTO substrate, and then transported to the photocathode through an external circuit; while photogenerated holes transfer from the valence band of BiVO4 to the valence band of CuFe2O4 and participate in the water oxidation reaction. This not only accelerates charge transfer and separation, but also suppresses hole recombination, resulting in the BiVO4 / CuFe2O4 composite electrode exhibiting a high photocurrent density.
[0023] (3) CuFe2O4 nanoparticles supported on BiVO4 surface have excellent chemical stability, which can effectively suppress photocorrosion and greatly improve electrode stability. Attached Figure Description
[0024] Figure 1 X-ray diffraction patterns of BiVO4 and BiVO4 / CuFe2O4 composite electrodes prepared in Example 1.
[0025] Figure 2 The image shows a scanning electron microscope (SEM) image of the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0026] Figure 3Transmission electron microscopy (TEM) image of the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0027] Figure 4 The X-ray photoelectron spectroscopy full scan spectrum of the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0028] Figure 5 Linear scan voltammetry curves of the BiVO4 electrode and BiVO4 / CuFe2O4 composite electrode prepared in Example 1 under illumination.
[0029] Figure 6 The charge separation efficiency curves are shown for the BiVO4 electrode and the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0030] Figure 7 The electronic lifetime curves are for the BiVO4 electrode and the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0031] Figure 8 Tafel slope curves for the BiVO4 electrode and the BiVO4 / CuFe2O4 composite electrode prepared in Example 1.
[0032] Figure 9 The stability curves of the BiVO4 electrode and the BiVO4 / CuFe2O4 composite electrode prepared in Example 1 under light irradiation are shown.
[0033] Figure 10 The linear sweep voltammetry curve of the BiVO4 / CuFe2O4 composite electrode prepared in Example 2 under illumination is shown.
[0034] Figure 11 The linear sweep voltammetry curve of the BiVO4 / CuFe2O4 composite electrode prepared in Example 3 under illumination is shown. Detailed Implementation
[0035] The technical solution of the present invention will be further described and illustrated below with reference to specific embodiments and accompanying drawings. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.
[0036] Example 1
[0037] The preparation method of the BiVO4 / CuFe2O4 composite electrode in Example 1 includes the following steps:
[0038] (1) A three-electrode system was constructed using FTO conductive glass as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl (saturated KCl solution) as the reference electrode. A 50 mL aqueous solution containing 0.5 g bismuth nitrate and 3 g potassium iodide with a pH of about 1.7 was mixed with a 0.23 mol / L p-benzoquinone solution and stirred as the electrolyte. The BiOI electrode was obtained by depositing a potential of -0.1 V vs. Ag / AgCl for 400 s.
[0039] (2) Take 60 μL of 3 mL of dimethyl sulfoxide solution containing 0.16 g of vanadium acetylacetonate and drop it onto the surface of the BiOI electrode obtained in (1) so that the vanadium acetylacetonate solution can be evenly covered on the surface of the BiOI material. Then put it into a muffle furnace and heat it to 450 °C at a rate of 2 °C / min. Hold it at this temperature for 1 h and let it cool naturally to room temperature. Place the BiVO4 electrode taken out into a 1 mol / L NaOH aqueous solution for 25 min to remove the residual V2O5 on the surface of the BiVO4 electrode. Then wash it repeatedly with deionized water to obtain the BiVO4 electrode.
[0040] (3) Dissolve copper nitrate, iron nitrate and citric acid in 100 mL of deionized water in a molar ratio of 1:2:3, place in a drying oven at 100 °C for 10 h, then take it out and grind it thoroughly. Then place the powder in a muffle furnace and heat it to 500 °C for 5 h to obtain CuFe2O4 powder.
[0041] (4) Take 60 μL of 0.10 mol / L CuFe2O4 solution and drop it onto the BiVO4 electrode. Then place it in a drying oven and heat it to 180℃ for 1 h to obtain the BiVO4 / CuFe2O4 composite electrode.
[0042] (5) The photoelectrocatalytic performance of the above materials was tested.
[0043] Example 2
[0044] Following the method of Example 1, the concentration of CuFe₂O₄ solution was changed to 0.3 mol / L and drop-coated onto the BiVO₄ electrode. The electrode was then placed in a drying oven and heated to 180°C for 2 hours. Other steps and parameters were the same as in Example 1.
[0045] Example 3
[0046] Following the method of Example 1, the concentration of CuFe2O4 solution was changed to 0.05 mol / L and drop-coated onto the BiVO4 electrode. The electrode was then placed in a drying oven and heated to 180°C for 2 hours. Other steps and parameters were the same as in Example 1.
[0047] Characterization and detection
[0048] Figure 1The image shows the X-ray diffraction pattern of the BiVO4 / CuFe2O4 photoanode prepared in Example 1. It can be seen that the main diffraction peaks in the pattern are consistent with the characteristic peaks of BiVO4 (JCPDS number 14-0688) and SnO2 (FTO substrate) (JCPDS number 46-1088). The BiVO4 / CuFe2O4 photoelectrode prepared in Example 1 was characterized by scanning electron microscopy, and the results are as follows... Figure 2 As shown, after loading CuFe2O4 nanoparticles, the surface of BiVO4 is covered by the accumulated tiny particles. Figure 3 The transmission electron microscope (TEM) image of the BiVO4 / CuFe2O4 composite photoanode clearly shows a distinct lattice. The crystal planes with lattice spacings of 0.181 nm and 0.21 nm belong to the (202) plane of BiVO4 and the (400) plane of CuFe2O4, respectively. Figure 4 The full-scan X-ray photoelectron spectroscopy pattern proves that CuFe2O4 nanoparticles were successfully loaded onto BiVO4.
[0049] In the photoelectrocatalytic water splitting test system, photocurrent density is a test method to measure the efficiency of semiconductor light energy absorption and conversion. The performance of the photoelectrocatalytic water splitting test was measured using an electrochemical analyzer (CHI660E) with a standard three-electrode system. A platinum sheet was used as the counter electrode, the photoelectrode under test was the working electrode, and the Ag / AgCl electrode was the reference electrode. The light source was simulated sunlight AM 1.5G (100mW cm⁻¹). -2 The electrolyte was a 0.5M potassium borate (KBi) solution (pH = 9.5), and the optical power was calibrated to 100 mW / cm² using a power meter. -2 The potential range for linear sweep spectroscopy (LSV) testing of photoelectrocatalytic performance was 0V to 1.5V vs. RHE, with a scan rate of 20mV / s. -1 .
[0050] Figure 5 Linear voltammetric curves for the BiVO4 and BiVO4 / CuFe2O4 photoanodes prepared in Example 1 are shown. Compared to the BiVO4 photoelectrode, the photocurrent density of the BiVO4 / CuFe2O4 photoelectrode is 2.77 mA cm⁻¹ at 1.23 V vs. RHE. -2 The efficiency is twice that of the BiVO4 electrode, indicating a significant improvement in PEC performance after incorporating CuFe2O4 nanoparticles. To demonstrate that loading CuFe2O4 nanoparticles onto the BiVO4 photoanode can improve carrier separation and suppress carrier recombination, the charge separation efficiency and electron lifetime of the BiVO4 electrode and the BiVO4 / CuFe2O4 electrode obtained in Example 1 were further tested. Figure 6As shown, the charge separation efficiency of the BiVO4 / CuFe2O4 electrode is 75.8%, which is much higher than that of the BiVO4 electrode (66.5%), proving that the loading of CuFe2O4 nanoparticles accelerates charge separation; while the... Figure 7 Electronic lifetime tests show that the electronic lifetime of the BiVO4 / CuFe2O4 electrode is 3.5s, which is longer than the 2.4s lifetime of the BiVO4 electrode. This proves that loading CuFe2O4 nanoparticles can suppress carrier recombination and prolong the lifetime of photogenerated carriers.
[0051] To demonstrate that CuFe₂O₄ nanoparticles can improve the water oxidation kinetics of the BiVO₄ photoelectrode, Tafel slope tests were performed on BiVO₄ and BiVO₄ / CuFe₂O₄ electrodes. This test directly reflects catalytic activity through the slope; a smaller slope indicates higher catalytic activity and better water oxidation kinetics. Figure 8 As shown, the slope of the BiVO4 photoelectrode is 143 mVdec. -1 The slope of the BiVO4 / CuFe2O4 photoelectrode is only 77 mV dec. -1 This demonstrates that loading CuFe2O4 nanoparticles can significantly improve the water oxidation kinetics of BiVO4 photoanodes.
[0052] Figure 9 The stability test diagrams of the BiVO4 and BiVO4 / CuFe2O4 photoelectrodes obtained in Example 1 are shown. The two photoelectrodes were tested for 8 hours under illumination. The results show that due to the reconstruction phenomenon, the PEC performance of the BiVO4 / CuFe2O4 photoelectrode increased rather than decreased, and the magnitude was large, indicating that the BiVO4 / CuFe2O4 photoelectrode has good stability.
[0053] Figure 10 and Figure 11 The LSVs of the 0.3 mol / L BiVO4 / CuFe2O4 photoelectrode and the 0.05 mol / L BiVO4 / CuFe2O4 photoelectrode obtained in Examples 2 and 3 are shown in the figure. As can be seen from the figure, the 0.3 mol / L photoanode can achieve a current density of 1.78 mA / cm² at a potential of 1.23 V vs. RHE. -2 A 0.05 mol / L photoanode exhibits a current density of 1.56 mA / cm² at 1.23 V vs. RHE potential. -2 Compared to BiVO4 photoanodes, this invention offers varying degrees of improvement, thus significantly enhancing the performance of the photoanode PEC.
[0054] The specific embodiments described herein are merely illustrative of the spirit of the invention and do not limit the scope of protection of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the invention or exceeding the scope defined by the appended claims.
Claims
1. A method for preparing a BiVO4 / CuFe2O4 composite photoanode, characterized in that, The preparation steps include: S1: A three-electrode system was constructed using FTO conductive glass as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode. An aqueous solution containing bismuth nitrate and potassium iodide was mixed with an ethanol solution containing p-benzoquinone as the electrolyte. The mixture was deposited at a certain potential, and the resulting electrode was denoted as BiOI. S2: A dimethyl sulfoxide solution containing vanadium acetylacetonate was drop-coated onto the BiOI electrode, then placed in a muffle furnace for calcination. After cooling to room temperature, it was immersed in NaOH solution for 20-30 minutes. The product after removal, washing and drying was denoted as BiVO4. S3: Heat an aqueous solution containing copper nitrate, ferric nitrate and citric acid in a drying oven to 50-100°C and maintain for 10-12 hours. After cooling to room temperature, grind the resulting substance into powder and then calcine it in a muffle furnace. The powder obtained after grinding is denoted as CuFe2O4. S4: Dissolve the CuFe2O4 powder in anhydrous ethanol, drop-coat it onto the BiVO4 electrode, and then calcine it in a muffle furnace. The resulting electrode is denoted as BiVO4 / CuFe2O4.
2. The method according to claim 1, characterized in that, The concentration of bismuth nitrate in the S1 aqueous solution is 0.04–0.06 mol / L, the concentration of potassium iodide is 0.04–0.06 mol / L, the concentration of p-benzoquinone solution is 0.2–0.3 mol / L, the volume ratio of aqueous solution to ethanol solution is 5:2, the deposition potential is -0.1±0.05V vs. Ag / AgCl, and the deposition time is 400–500 s.
3. The method according to claim 1, characterized in that, The concentration of vanadium acetylacetone in S2 is 0.1–0.3 mol / L, the calcination temperature in the muffle furnace is 400–500℃, the heating rate is 1–3℃ / min, and the holding time is 0.5–1.5 h.
4. The method according to claim 1, characterized in that, In S3, copper nitrate, ferric nitrate, and citric acid are mixed in a molar ratio of 1:2:
3. The calcination temperature in the muffle furnace is 400–500℃, the heating rate is 3–5℃ / min, and the holding time is 4–6h.
5. The method according to claim 1, characterized in that, The concentration of CuFe2O4 solution in S4 is 0.05–0.15 mol / L, the calcination temperature in the muffle furnace is 150–200℃, the heating rate is 5–10℃ / min, and the holding time is 0.5–1.5 h.
6. A BiVO4 / CuFe2O4 composite photoanode, characterized in that, The BiVO4 / CuFe2O4 composite photoanode is prepared by the method described in any one of claims 1-5.
7. The application of the BiVO4 / CuFe2O4 composite photoanode as described in claim 6 in photoelectrocatalytic water splitting.