Preparation method and application of Z-type heterojunction photoelectrode
阅读说明：本技术 一种z型异质结光电极的制备方法和用途 (Preparation method and application of Z-type heterojunction photoelectrode ) 是由 白亚杰 范伟强 白红叶 于 2021-08-31 设计创作，主要内容包括：本发明属于纳米材料合成技术领域,特指一种Z型异质结光电极的制备方法和用途。本发明首先采用水热反应在FTO基片上制备出BiVO-(4)纳米棒阵列,继而再使用电沉积法在BiVO-(4)表面形成一层PANI,最终形成BiVO-(4)/PANI异质结光电极。所述异质结光电极可用于可见光下光电催化氮气还原反应。(The invention belongs to the technical field of nano material synthesis, and particularly relates to a preparation method and application of a Z-type heterojunction photoelectrode. Firstly, preparing BiVO on FTO substrate by adopting hydrothermal reaction 4 Nanorod array, and then electrodepositing on BiVO 4 Forming a layer of PANI on the surface to finally form BiVO 4 a/PANI heterojunction photoelectrode. The heterojunction photoelectrode can be used for photoelectrocatalysis nitrogen reduction reaction under visible light.)
1. A preparation method of a Z-type heterojunction photoelectrode is characterized by firstly adopting a hydrothermal reaction to prepare BiVO on an FTO substrate4Nanorod array, and then electrodepositing on BiVO4Forming a layer of PANI on the surface to finally form BiVO4the/PANI heterojunction photoelectrode comprises the following specific steps:
(1) to HNO3Adding Bi (NO) into the solution3)3·5H2O and EDTA-2Na are marked as solution A; reacting NH4VO3And EDTA-2Na are dissolved in the NaOH solution and marked as solution B; mixing the solution A and the solution B to obtain a mixed solution;
(2) transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, carrying out hydrothermal reaction, and then naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array;
(3) to H2SO4Adding acetic acid into the solution, and stirring to form a uniform mixed solution C; depositing a single layer of BiVO on the surface4And taking out the FTO substrate of the nanorod array, washing the FTO substrate with deionized water, and then putting the FTO substrate into the solution C for constant potential deposition to obtain the Z-type heterojunction photoelectrode.
2. The method for preparing a Z-type heterojunction photoelectrode as claimed in claim 1, wherein in the step (1), the HNO is added3The concentration of the solution was 2M, HNO3Solution, Bi (NO)3)3·5H2The ratio of O to EDTA-2Na was 40 mL: 1.9 g: 1.5 g; the concentration of the NaOH solution is 1M; NH (NH)4VO3The ratio of EDTA-2Na to NaOH solution was 0.5 g: 1.5 g: 80 mL; the volume ratio of the solution A to the solution B is 1: 2.
3. the method for preparing a Z-type heterojunction photoelectrode as claimed in claim 1, wherein in the step (2), the hydrothermal reaction is constant temperature 12h when the temperature is raised to 160 ℃.
4. The method for preparing a Z-type heterojunction photoelectrode as claimed in claim 1, wherein in the step (3), the H is2SO4The concentration of the solution was 0.1M, H2SO4The volume ratio of the solution to acetic acid was 50 mL: 900 mu L; the deposition process conditions of the constant potential (1.4V vs. RHE) are as follows: with BiVO4Is used as a working electrode, Ag/AgCl is used as a reference electrode, a platinum wire is used as a counter electrode for electrodeposition, and BiVO is repeatedly washed by deionized water4the/PANI samples were dried at room temperature.
5. The method for preparing a Z-type heterojunction photoelectrode as claimed in claim 4, wherein the electrodeposition time is 20 min.
6. Use of a Z-type heterojunction photoelectrode prepared by the preparation method according to any one of claims 1 to 5 as a working electrode for photoelectrochemical nitrogen reduction under visible light conditions.
Technical Field
The invention belongs to the technical field of synthesis of nano materials, and particularly relates to a preparation method and application of a Z-type heterojunction photoelectrode.
Background
Since the 21 st century, the excessive use of fossil energy has resulted in serious destruction of global environment, so the development and utilization of green energy has become one of the most important challenges facing mankind at present; photoelectrochemical nitrogen reduction (PEC NRR) is a promising technology that allows the conversion of solar energy to chemical energy and a pollution-free combustion process that gives hydrogen an unparalleled advantage in terms of green energy. The performance of the PEC NRR is directly affected by absorption spectroscopy, photo-generated charge transfer, bandgap structure and stability, and therefore designing new semiconductor electrodes is an effective entry point to improve the efficiency of the PEC NRR.
Bismuth vanadate (BiVO)4) Is a known solar ammonia-producing semiconductor, but BiVO is a cause of4The wide forbidden band (about 2.7eV) can only respond to ultraviolet light (about 5% of sunlight), which greatly limits BiVO4The photoelectric conversion efficiency of (1).
The heterojunction has high-quality catalytic activity, a simple active center structure and an adjustable electronic structure, and is widely applied to the fields of photocatalysis, electrocatalysis and the like. Polyaniline (PANI) is a potentially large material with huge photocatalytic and electrochemical properties, and is an excellent catalyst for constructing heterojunctions to improve NRR performance. The interface polarization field triggered by the extreme electric field excited by the heterojunction interface can better drive electrons on the catalyst to N2And (5) transferring.
PANI is a polymer material with electrical conductivity and visible light sensitivity, and has attracted attention due to its low cost, strong environmental and chemical stability, high electrical conductivity, and unique redox properties. The key point is that the combination of PANI and the semiconductor can well improve the migration efficiency of photo-carriers at the interface of polyaniline and the semiconductor, thereby promoting the separation of the photo-carriers and improving the photocatalytic performance.
Disclosure of Invention
The purpose of the invention is as follows: one, provide a simple Z type BiVO4And secondly, applying the prepared heterojunction material as a working electrode to PEC NRR.
Firstly, preparing BiVO on FTO substrate by adopting hydrothermal reaction4Nanorod array, and then electrodepositing on BiVO4Forming a layer of PANI on the surface to finally form BiVO4a/PANI heterojunction photoelectrode.
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. prepared on an FTO substrateBiVO4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) to HNO3Adding Bi (NO) into the solution3)3·5H2O and EDTA-2Na are marked as solution A; reacting NH4VO3And EDTA-2Na are dissolved in the NaOH solution and marked as solution B; and mixing the solution A and the solution B to obtain a mixed solution.
The HNO3The concentration of the solution was 2M, HNO3Solution, Bi (NO)3)3·5H2The ratio of O to EDTA-2Na was 40 mL: 1.9 g: 1.5 g.
The concentration of the NaOH solution is 1M; NH (NH)4VO3The ratio of EDTA-2Na to NaOH solution was 0.5 g: 1.5 g: 80 mL.
The volume ratio of the solution A to the solution B is 1: 2.
(2) transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
to H2SO4Adding acetic acid into the solution, and stirring to form a uniform mixed solution C; depositing a single layer of BiVO on the surface4And taking out the FTO substrate of the nanorod array, washing the FTO substrate with deionized water, and then putting the FTO substrate into the solution C for constant potential deposition to obtain the Z-type heterojunction photoelectrode.
Said H2SO4The concentration of the solution was 0.1M, H2SO4The volume ratio of the solution to acetic acid was 50 mL: 900 mu L; the deposition process conditions of the constant potential (1.4V vs. RHE) are as follows: with BiVO4Is a working electrode, Ag/AgCl is a reference electrode, and a platinum wire is a counter electrode for electrodeposition. Repeatedly rinsing BiVO with deionized water4the/PANI samples were dried at room temperature.
The phase and structure of the composite electrode in the present invention were determined by X-ray diffraction experiments (fig. 1); the catalytic performance of the composite electrode of the present invention was determined from the current-voltage (I-V) characteristic curve under nitrogen (fig. 2).
BiVO4The method for testing the current-voltage characteristic curve of the PANI heterojunction photoelectrode under the irradiation of the xenon lamp light source comprises the following steps: in an electrochemical work station of the CHI 852C type, 0.1M lithium sulphate (Li) is introduced into the cell2SO4) As electrolyte, silver chloride electrode as reference electrode, platinum electrode as counter electrode, BiVO4the/PANI heterojunction material is used as a working electrode. During the test, nitrogen was continuously introduced into the reactor to saturate the entire reaction system and provide an adequate nitrogen source for the NRR.
Advantageous effects
BiVO prepared by simple hydrothermal synthesis method and chemical bath deposition method4The material has the advantages of good chemical stability and good photoelectrochemical performance; the method has the advantages of simple process, good repeatability, cheap and easily obtained materials and environmental-friendly requirement.
Drawings
FIG. 1 is an X-ray diffraction pattern (XRD) of a sample prepared according to the present invention, in which BiVO is present4the/PANI heterojunction composite material shows BiVO4Characteristic peak of (1), and pure BiVO4The comparison showed no other new peaks.
FIG. 2 shows BiVO prepared by the present invention4High Resolution Transmission Electron Microscopy (HRTEM) of the/PANI heterojunction, in which BiVO is clearly shown4The lattice fringes of (a) were 0.49nm, and PANI showed no lattice fringes. FIGS. 1 and 2 illustrate the successful synthesis of BiVO4a/PANI heterojunction, and PANI is an amorphous material.
FIG. 3 shows BiVO prepared by the present invention4X-ray photoelectron spectroscopy (XPS) of/PANI heterojunction: (a) combining XPS, (b) Bi 4f, (b) V2 p, (C) O1 s, N1s and (d) C1s, XPS spectra show that it contains all the elements of the synthesized sample.
FIG. 4 is a graph of samples prepared according to examples 1-5 of the present invention under visible light conditionsGraph of the effect of photoelectrochemical nitrogen reduction. BiVO can be seen in the figure4The nitrogen reduction efficiency of the/PANI-20 heterojunction is highest. Illustrating the synthetic BiVO4the/PANI-20 heterojunction catalyst can remarkably improve the photocatalytic performance and can be well applied to nitrogen reduction reaction under visible light.
Detailed Description
The present invention will be described in detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.
Example 1
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. preparing BiVO on FTO substrate4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) 2M HNO at 40mL3To the solution was added 1.9g of Bi (NO)3)3·5H2O and 1.5g of EDTA-2Na are designated as solution A. 0.5g of NH4VO3And 1.5g EDTA-2Na dissolved in 80mL 1M NaOH solution, marking as solution B; and mixing the solution A and the solution B to obtain a mixed solution.
(2) Transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
(1) to 50mL H2SO4To (0.1M) was added 900. mu.L of acetic acid, and the mixture was stirred to form a uniform mixed solution C.
(2) The FTO substrate was removed, washed clean with deionized water, and then placed in solution C for 5min of potentiostatic (1.4V vs. RHE) deposition. Obtaining BiVO4the/PANI-5 heterojunction photoelectrode.
Example 2
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. preparing BiVO on FTO substrate4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) 2M HNO at 40mL3To the solution was added 1.9g of Bi (NO)3)3·5H2O and 1.5g of EDTA-2Na are designated as solution A. 0.5g of NH4VO3And 1.5g EDTA-2Na dissolved in 80mL 1M NaOH solution, marking as solution B; and mixing the solution A and the solution B to obtain a mixed solution.
(2) Transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
(1) to 50mL H2SO4To (0.1M) was added 900. mu.L of acetic acid, and the mixture was stirred to form a uniform mixed solution C.
(2) The FTO substrate was removed, washed clean with deionized water, and then placed in solution C for potentiostatic (1.4V vs. rhe) deposition for 10 min. Obtaining BiVO4the/PANI-10 heterojunction photoelectrode.
Example 3
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. preparing BiVO on FTO substrate4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) 2M HNO at 40mL3To the solution was added 1.9g of Bi (NO)3)3·5H2O and 1.5g of EDTA-2Na are designated as solution A. 0.5g of NH4VO3And 1.5g of EDTA-2Na dissolved in 80mLIn the NaOH solution with the concentration of 1M, marking as a solution B; and mixing the solution A and the solution B to obtain a mixed solution.
(2) Transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
(1) to 50mL H2SO4To (0.1M) was added 900. mu.L of acetic acid, and the mixture was stirred to form a uniform mixed solution C.
(2) The FTO substrate was removed, washed clean with deionized water, and then placed in solution C for potentiostatic (1.4V vs. rhe) deposition for 15 min. Obtaining BiVO4the/PANI-15 heterojunction photoelectrode.
Example 4
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. preparing BiVO on FTO substrate4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) 2M HNO at 40mL3To the solution was added 1.9g of Bi (NO)3)3·5H2O and 1.5g of EDTA-2Na are designated as solution A. 0.5g of NH4VO3And 1.5g EDTA-2Na dissolved in 80mL 1M NaOH solution, marking as solution B; and mixing the solution A and the solution B to obtain a mixed solution.
(2) Transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
(1) to 50mL H2SO4To (0.1M) was added 900. mu.L of acetic acid, and the mixture was stirred to form a uniform mixed solution C.
(2) The FTO substrate was removed, washed clean with deionized water, and then placed in solution C for potentiostatic (1.4V vs. rhe) deposition for 20 min. Obtaining BiVO4the/PANI-20 heterojunction photoelectrode.
Example 5
The preparation method of the heterojunction photoelectrode is carried out according to the following steps:
A. preparing BiVO on FTO substrate4A nanorod array.
Preparing BiVO on FTO substrate4The nanorod array comprises the following steps:
(1) 2M HNO at 40mL3To the solution was added 1.9g of Bi (NO)3)3·5H2O and 1.5g of EDTA-2Na are designated as solution A. 0.5g of NH4VO3And 1.5g EDTA-2Na dissolved in 80mL 1M NaOH solution, marking as solution B; and mixing the solution A and the solution B to obtain a mixed solution.
(2) Transferring the mixed solution into a reaction kettle with a tetrafluoroethylene lining, putting a cleaned FTO substrate into the reaction kettle, enabling the conductive surface to face downwards, heating to 160 ℃, keeping the temperature for 12 hours, and naturally cooling to obtain the BiVO with a single layer deposited on the surface4FTO substrate of nano-rod array.
B. Preparation of BiVO4a/PANI heterojunction.
The preparation of BiVO4The method for the PANI heterojunction comprises the following steps:
(1) to 50mL H2SO4To (0.1M) was added 900. mu.L of acetic acid, and the mixture was stirred to form a uniform mixed solution C.
(2) The FTO substrate was removed, washed clean with deionized water, and then placed in solution C for potentiostatic (1.4V vs. rhe) deposition for 25 min. Obtaining BiVO4the/PANI-25 heterojunction photoelectrode.
Preparing BiVO with different proportions by controlling the time of electrodeposition4(ii) a/PANI heterojunction photoelectrode in sunlight (300W xenon lamp; 100 mW/cm)2) Next, consider eachBiVO at different deposition times4The photoelectrochemical nitrogen reduction performance of the PANI heterojunction and the optimal deposition time of the PANI heterojunction are searched through the photoelectrocatalysis performance. BiVO (BiVO) is displayed by photoelectrochemical nitrogen reduction results4the/PANI-20 heterojunction has optimal PEC NRR performance.
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