Preparation method and application of bi4v4 / co(o h)f / feoo h composite photo-anode

Abstract

The application discloses a preparation method of a BiVO4 / Co(OH)F / FeOOH composite photoanode and application thereof. A composite Co(OH)F / FeOOH is used as a cocatalyst to be loaded on a BiVO4 photoanode to form a BiVO4 / Co(OH)F / FeOOH composite photoanode. The optimized BiVO4 / Co(OH)F / FeOOH composite photoanode has a photocurrent density of 3.04 mA / cm 2 under a 1.23 V vs. RHE bias voltage and continuous illumination for 3000 s, and the photocurrent density loss rate of the composite electrode is still within 15% of the initial value. The introduction of the Co(OH)F / FeOOH cocatalyst layer greatly improves the catalytic performance and stability of the BiVO4 material.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrochemistry, and specifically relates to a method for preparing and applying a BiVO4 / Co(OH)F / FeOOH composite photoanode. Background Technology

[0002] To address the adverse effects of energy shortages and environmental pollution on global sustainable development, the development of clean and efficient new energy sources is imperative. Hydrogen energy, with its zero carbon emissions and high energy density, is considered the best option for addressing future energy crises, while the photoelectrochemical (PEC) water splitting method utilizing solar energy shows great promise. Bismuth monoclinic vanadate (BiVO4), as one of the representative materials for the photoanode in PEC water splitting, possesses a high theoretical photocurrent value (7.5 mA / cm²). 2 BiVO4 exhibits a relatively ideal visible light absorption bandgap. However, the slow transfer rate of photogenerated carriers and hole recombination result in a photocurrent density far lower than the theoretical value, and the slow reaction kinetics also greatly limit the development of BiVO4. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention utilizes the composite material Co(OH)F / FeOOH as a co-catalyst to synergistically enhance the PEC performance of BiVO4 materials. The optimized BiVO4 / Co(OH)F / FeOOH composite photoanode significantly improves the catalytic performance and stability of BiVO4 materials.

[0004] The technical solution adopted in this invention is: a method for preparing BiVO4 / Co(OH)F / FeOOH composite photoanode, wherein the composite material Co(OH)F / FeOOH is used as a co-catalyst and loaded on BiVO4 photoanode to form BiVO4 / Co(OH)F / FeOOH composite photoanode.

[0005] Furthermore, the preparation method of the above-mentioned BiVO4 / Co(OH)F / FeOOH composite photoanode includes the following steps: ferrous sulfate heptahydrate is dissolved in sodium sulfate solution and sonicated for 3 min to prepare an electrodeposition solution. The BiVO4 / Co(OH)F photoanode is immersed in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Electrodeposition is performed for 1300s-1700s using the three-electrode system under an applied bias voltage of 0.06V vs Ag / AgCl. The electrodeposition is then carried out with deionized water and dried with nitrogen to obtain the BiVO4 / Co(OH)F / FeOOH composite photoanode.

[0006] Furthermore, the preparation method of the above-mentioned BiVO4 / Co(OH)F / FeOOH composite photoanode, wherein the preparation method of the BiVO4 / Co(OH)F photoanode includes the following steps: ultrasonically dissolving cobalt nitrate hexahydrate in deionized water, then adding ammonium fluoride and hydrazine hydrate sequentially, stirring for 10 min, transferring the resulting mixed solution to a stainless steel autoclave pre-loaded with a BiVO4 photoanode, and carrying out a hydrothermal reaction. After the reaction is completed, the material is removed and rinsed with deionized water to obtain the BiVO4 / Co(OH)F photoanode.

[0007] Furthermore, in the above-mentioned method for preparing the BiVO4 / Co(OH)F / FeOOH composite photoanode, the hydrothermal reaction is carried out at 100°C for 6 hours.

[0008] Furthermore, the preparation method of the above-mentioned BiVO4 / Co(OH)F / FeOOH composite photoanode, wherein the preparation method of the BiVO4 photoanode includes the following steps:

[0009] 1) Preparation of electrodeposition solution: Take a nitric acid solution with pH=1.7, add Bi(NO3)3·5H2O, sonicate at 25℃ for 10 min, add potassium iodide, stir vigorously until completely dissolved to obtain solution A; mix the ethanol solution of p-benzoquinone with solution A, and continue sonicating until no precipitate is obtained to obtain electrodeposition solution.

[0010] 2) Preparation of BiVO4 photoanode: The electrodeposition solution was placed in a container and connected to an electrochemical workstation. FTO was immersed in the electrodeposition solution as the working electrode, Pt wire was used as the counter electrode, and Ag / AgCl electrode was used as the reference electrode. Using a three-electrode system, BiOI film was prepared by electrodeposition for 5 min under an applied bias voltage of -0.1V vs. Ag / AgCl. Vanadium acetylacetonate was dissolved in dimethyl sulfoxide, and the resulting solution was uniformly drop-coated onto the BiOI surface. The solution was then calcined in a muffle furnace, cooled, and immersed in a 1 mol / L NaOH aqueous solution for 30 min. The solution was rinsed with deionized water and dried with N2 to obtain the BiVO4 photoanode.

[0011] Furthermore, in the above-mentioned method for preparing the BiVO4 / Co(OH)F / FeOOH composite photoanode, the calcination is carried out by heating to 450°C at a heating rate of 2°C / min and continuing to heat for 2 hours.

[0012] The application of the BiVO4 / Co(OH)F / FeOOH composite photoanode provided by this invention in the catalytic desorption of oxygen from water under visible light.

[0013] The beneficial effects of this invention are: This invention uses the composite material Co(OH)F / FeOOH as a co-catalyst to synergistically enhance the PEC performance of BiVO4 material. The optimized BiVO4 / Co(OH)F / FeOOH composite photoanode exhibits a photocurrent density of 3.04 mA / cm² at 1.23 V vs RHE. 2 Under continuous illumination for 3000 s with an applied bias voltage of 0.8V vs RHE, the photocurrent density loss rate of the composite electrode remained within 15% of the initial value. The introduction of the Co(OH)F / FeOOH cocatalyst layer significantly improved the catalytic performance and stability of the BiVO4 material. Attached Figure Description

[0014] Figure 1 This is a transmission electron microscope (TEM) image of BiVO4 / Co(OH)F / FeOOH.

[0015] Figure 2 These are XRD patterns of different materials BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH.

[0016] Figure 3 These are linear sweep voltammetry (LSV) curves of three different photoelectrodes: BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH.

[0017] Figure 4 BiVO4 / Co(OH)F / FeOOH formed at different deposition times t LSV of photoanode (t = 1300s, 1500s, 1700s).

[0018] Figure 5 The figure shows the chronoamperometry of three different photoelectrodes, BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH, under an applied bias voltage of 0.8V vsRHE. Detailed Implementation

[0019] Example 1

[0020] (I) BiVO4 / Mn-Co(OH)F composite photoanode, the preparation method is as follows:

[0021] 1. Preparation of BiVO4:

[0022] 2.91 g of bismuth nitrate pentahydrate was added to 150 mL of nitric acid aqueous solution with pH = 1.7. After sonication for 5 min, 9.96 g of potassium iodide was added, and the mixture was stirred until the solution turned reddish-brown, yielding solution A. 60 mL of 0.23 mol / L p-benzoquinone ethanol solution was mixed with solution A, and stirring was continued to form a dark red solution, yielding the electrodeposition solution.

[0023] Take an appropriate amount of electrodeposition solution in a container, immerse a cleaned FTO conductive glass in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Using a three-electrode system, electrodeposit for about 5 minutes under an applied bias voltage of -0.1V vs. Ag / AgCl. After removal, rinse the electrodeposited layer with deionized water and then dry it with nitrogen to prepare a BiOI thin film. Dissolve 0.106g of vanadium acetylacetonate in 1.0mL of dimethyl sulfoxide (DMSO), sonicate until completely dissolved, and use a pipette to take 30μL and uniformly drop it onto the BiOI surface. Place it in a muffle furnace and heat it to 450℃ at a heating rate of 2℃ / min. Calcinate for 2 hours. After cooling, remove it and soak it in a 1mol / L sodium hydroxide solution for about 30 minutes with rotor stirring until the BiVO4 surface turns golden yellow. Remove the V2O5 on the BiVO4 surface, rinse with deionized water, and dry with nitrogen to obtain a BiVO4 photoanode.

[0024] 2. Preparation of BiVO4 / Co(OH)F:

[0025] At room temperature, 1 mmol of cobalt nitrate hexahydrate was ultrasonically dissolved in 30 mL of deionized water. Then, 0.187 g of ammonium fluoride and 100 μL of hydrazine hydrate were added sequentially and stirred for 10 min. The resulting mixture was transferred to a 50 mL stainless steel autoclave, and a BiVO4 photoanode was pre-added to it. The autoclave was then hydrothermally reacted at 100 °C for 6 h. After the reaction was completed, the material was removed and rinsed with deionized water to obtain the BiVO4 / Co(OH)F photoanode.

[0026] 3. Preparation of BiVO4 / Co(OH)F / FeOOH composite photoanode:

[0027] Dissolve 0.5g of ferrous sulfate heptahydrate in 20mL of 0.1mol / L sodium sulfate solution and sonicate for 3min to prepare an electrodeposition solution.

[0028] The BiVO4 / Co(OH)F photoanode was immersed in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Electrodeposition was performed for 1500 s using the three-electrode system under an applied bias voltage of 0.06 V vs Ag / AgCl. After electrodeposition, the electrode was removed, the electrodeposition layer was rinsed with deionized water, and then dried with nitrogen gas to obtain the BiVO4 / Co(OH)F / FeOOH composite photoanode.

[0029] (II) Characterization

[0030] Figure 1 This is a transmission electron microscope (TEM) image of BiVO4 / Co(OH)F / FeOOH. (From...) Figure 1 It can be seen that the Co(OH)F / FeOOH cocatalyst layer was successfully prepared and successfully loaded onto the BiVO4 photoanode.

[0031] Figure 2 These are XRD patterns of different materials, including BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH. From... Figure 2 The comparison shows that when Co(OH)F and Co(OH)F / FeOOH cocatalyst layers were loaded onto BiVO4 material, no significant peak changes were observed. This is presumably due to the low loading of the cocatalyst. However, scanning electron microscopy and transmission electron microscopy images clearly show that the Co(OH)F / FeOOH composite cocatalyst was successfully loaded onto BiVO4 material.

[0032] Example 2

[0033] (I) BiVO4 / Mn-Co(OH)F composite photoanode, the preparation method is as follows:

[0034] 1. Preparation of BiVO4: Same as in Example 1

[0035] 2. Preparation of BiVO4 / Co(OH)F: Same as in Example 1

[0036] 3. Preparation of BiVO4 / Co(OH)F / FeOOH composite photoanode:

[0037] Dissolve 0.5g of ferrous sulfate heptahydrate in 20mL of 0.1mol / L sodium sulfate solution and sonicate for 3min to prepare an electrodeposition solution.

[0038] The BiVO4 / Co(OH)F photoanode was immersed in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Electrodeposition was performed for 1300 s using the three-electrode system under an applied bias voltage of 0.06 V vs Ag / AgCl. After electrodeposition, the electrode was removed, the electrodeposition layer was rinsed with deionized water, and then dried with nitrogen gas to obtain the BiVO4 / Co(OH)F / FeOOH composite photoanode.

[0039] Example 3

[0040] (I) BiVO4 / Mn-Co(OH)F composite photoanode, the preparation method is as follows:

[0041] 1. Preparation of BiVO4: Same as in Example 1

[0042] 2. Preparation of BiVO4 / Co(OH)F: Same as in Example 1

[0043] 3. Preparation of BiVO4 / Co(OH)F / FeOOH composite photoanode:

[0044] Dissolve 0.5g of ferrous sulfate heptahydrate in 20mL of 0.1mol / L sodium sulfate solution and sonicate for 3min to prepare an electrodeposition solution.

[0045] The BiVO4 / Co(OH)F photoanode was immersed in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Electrodeposition was performed for 1700 s using the three-electrode system under an applied bias voltage of 0.06 V vs Ag / AgCl. After electrodeposition, the electrode was removed, the electrodeposition layer was rinsed with deionized water, and then dried with nitrogen gas to obtain the BiVO4 / Co(OH)F / FeOOH composite photoanode.

[0046] Example 4

[0047] Application of BiVO4 / Co(OH)F / FeOOH composite photoanode in visible light catalytic water desorption and oxygen removal

[0048] Electrochemical performance testing of the electrode: The electrochemical performance of the composite electrode was tested using a CHI 660 electrochemical workstation. During the test, a three-electrode system was used (BiVO4 / Co(OH)F / FeOOH composite photoanode as the working electrode, Ag / AgCl as the reference electrode, and platinum wire as the counter electrode). The electrolyte solution was a 1.0M potassium borate buffer solution with a pH of 9.5, and the xenon lamp intensity was 100 mW / cm². 2 The scan rate was 50 mV / s. -1 The measured potentials were all converted to RHE(E) RHE =E Ag / AgCl +0.197V +0.059pH).

[0049] Figure 3 The linear sweep voltammetry (LSV) curves for three different photoelectrodes: BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH. The unmodified BiVO4 photoanode current density is 1.53 mA / cm² at 1.23 V vs RHE. 2 When Co(OH)F is coupled to BiVO4, the photocurrent density of BiVO4 / Co(OH)F increases to 2.27 mA / cm² at 1.23 V vs RHE. 2The final designed photoanode, BiVO4 / Co(OH)F / FeOOH, achieved a photocurrent density of 3.04 mA / cm² at 1.23 V vs RHE. 2 This indicates that the loading of the composite cocatalyst layer BiVO4 / Co(OH)F / FeOOH significantly improves the photoelectrochemical water splitting catalytic activity of BiVO4.

[0050] Figure 4 BiVO4 / Co(OH)F / FeOOH formed at different deposition times t LSV of the photoanode (t = 1300s, 1500s, 1700s). The LSV data clearly shows that at 1.23V vs RHE, the BiVO4 / Co(OH)F / FeOOH photoelectrodeposited for 1500s exhibits the highest photocurrent density. This indicates that deposition time is crucial for the catalytic performance of FeOOH. Shorter deposition times do not achieve optimal catalytic effects, while longer deposition times result in an excessively thick FeOOH co-catalyst layer, hindering carrier transport.

[0051] Figure 5 The figures show the chronoamperometry of three different photoelectrodes, BiVO4, BiVO4 / Co(OH)F, and BiVO4 / Co(OH)F / FeOOH, under a 0.8V vsRHE bias. Under continuous illumination for 3000 s, the stability of BiVO4 / Co(OH)F / FeOOH is significantly better than that of BiVO4 and BiVO4 / Co(OH)F, and the photocurrent density remains within 85% of the initial photocurrent value. This indicates that the prepared material exhibits excellent stability and photoelectrochemical water splitting catalytic activity.

Claims

1. A method for preparing a BiVO4 / Co(OH)F / FeOOH composite photoanode, characterized in that, A BiVO4 / Co(OH)F / FeOOH composite photoanode was formed by supporting the composite material Co(OH)F / FeOOH as a cocatalyst on a BiVO4 photoanode. The preparation method includes the following steps. Cobalt nitrate hexahydrate was ultrasonically dissolved in deionized water, and then ammonium fluoride and hydrazine hydrate were added sequentially. The resulting mixed solution was transferred to a stainless steel autoclave pre-loaded with a BiVO4 photoanode for hydrothermal reaction. After the reaction was completed, the material was removed and rinsed with deionized water to obtain the BiVO4 / Co(OH)F photoanode. Ferrous sulfate heptahydrate was dissolved in sodium sulfate solution to prepare an electrodeposition solution. The BiVO4 / Co(OH)F photoanode was immersed in the electrodeposition solution as the working electrode, Ag / AgCl as the reference electrode, and Pt wire as the counter electrode. Electrodeposition was performed for 1300-1700 s using the three-electrode system under an applied bias voltage of 0.06 V vsAg / AgCl. The electrodeposition was then performed by rinsing with deionized water and drying with nitrogen gas to obtain the BiVO4 / Co(OH)F / FeOOH composite photoanode.

2. The preparation method of the BiVO4 / Co(OH)F / FeOOH composite photoanode according to claim 1, characterized in that, Ferrous sulfate heptahydrate was dissolved in sodium sulfate solution and sonicated for 3 minutes to prepare an electrodeposition solution.

3. The preparation method of the BiVO4 / Co(OH)F / FeOOH composite photoanode according to claim 2, characterized in that, Cobalt nitrate hexahydrate was ultrasonically dissolved in deionized water, and then ammonium fluoride and hydrazine hydrate were added sequentially. The mixture was stirred for 10 minutes to obtain a mixed solution.

4. The preparation method of the BiVO4 / Co(OH)F / FeOOH composite photoanode according to claim 3, characterized in that, The hydrothermal reaction is carried out at 100°C for 6 hours.

5. The method for preparing the BiVO4 / Co(OH)F / FeOOH composite photoanode according to claim 3, characterized in that, The preparation method of the BiVO4 photoanode includes the following steps: 1) Preparation of electrodeposition solution: Take a nitric acid solution with pH=1.7, add Bi(NO3)3•5H2O, sonicate at 25 ℃ for 10 min, add potassium iodide, stir vigorously until completely dissolved to obtain solution A; mix the ethanol solution of p-benzoquinone with solution A, and continue sonicating until no precipitate is obtained to obtain the electrodeposition solution. 2) Preparation of BiVO4 photoanode: The electrodeposition solution was placed in a container and connected to an electrochemical workstation. FTO was immersed in the electrodeposition solution as the working electrode, Pt wire was used as the counter electrode, and Ag / AgCl electrode was used as the reference electrode. Using a three-electrode system, BiOI film was prepared by electrodeposition for 5 min under an applied bias voltage of -0.1 V vs. Ag / AgCl. Vanadium acetylacetonate was dissolved in dimethyl sulfoxide, and the resulting solution was uniformly drop-coated onto the BiOI surface. The solution was then calcined in a muffle furnace, cooled, and immersed in 1 mol / L NaOH aqueous solution for 30 min. The solution was rinsed with deionized water and dried with N2 to obtain the BiVO4 photoanode.

6. The method for preparing the BiVO4 / Co(OH)F / FeOOH composite photoanode according to claim 5, characterized in that, The calcination process involves heating the temperature to 450 °C at a rate of 2 °C / min and continuing the heating for 2 hours.

7. The application of the BiVO4 / Co(OH)F / FeOOH composite photoanode prepared according to any one of claims 1-6 in the catalytic desorption of oxygen from water under visible light.

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