Preparation method and application of electrochemical activated MXene modified BiVO4 photoelectrode

Abstract

The invention discloses a preparation method and application of an electrochemically activated MXene modified BiVO4 photoelectrode, and the preparation method of the electrochemically activated MXene modified BiVO4 photoelectrode comprises the following steps: by taking a BiVO4 photoelectrode as a working electrode and a solution containing layered MXene as an electrolyte, depositing MXene on the BiVO4 photoelectrode through an electrophoresis method to obtain an MXene / BiVO4 composite photoelectrode; and applying a bias voltage to the MXene / BiVO4 composite photoelectrode to activate the MXene / BiVO4 composite photoelectrode, so as to obtain the electrochemical activated MXene modified BiVO4 photoelectrode. According to the preparation method and the application of the electrochemically activated MXene modified BiVO4 photoelectrode, the electrochemically activated MXene modified BiVO4 photoelectrode has excellent photoelectrocatalytic activity, and has an excellent effect on photoelectrocatalytic water decomposition.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectrode materials, and in particular relates to a preparation method and application of an electrochemically activated MXene-modified BiVO4 photoelectrode. Background Art

[0002] With the pollution and irreversible consumption of fossil fuels, energy shortage has become a serious challenge and has attracted increasing attention from human society. Photoelectrochemical water splitting (PEC) provides an attractive strategy to obtain oxygen and hydrogen by directly converting solar energy into chemical energy, which can solve energy shortage and environmental pollution. In the past few decades, people have devoted themselves to the study of photoelectrodes with excellent performance, such as α-Fe2O3, Ta3N5, ZnO, BiVO4, WO3, TiO2, CdS, etc. Among them, monoclinic bismuth vanadate (BiVO4) is considered to be an ideal photoelectrode in PEC water splitting. BiVO4 has attracted much attention due to its suitable band gap, suitable band position, excellent visible light response, low toxicity and other advantages. However, the PEC water splitting performance of BiVO4 is severely limited by the high recombination rate of photogenerated electron-hole pairs and the slow interface-related water oxidation process. Therefore, the actual photocurrent density of pure BiVO4 is significantly lower than its theoretical value of 7.5mA / cm 2 (AM 1.5G, 100mW / cm 2 ).

[0003] At present, the modification technology of original BiVO4 mainly focuses on the structure of the material itself, including element doping (Angew.Chem.Int.Ed.2024,e202416340), nanostructure regulation (Chemical Engineering Journal2023,465,142571), co-catalyst loading (ACS Appl.Nano Mater.2024,7,14115-14122), heterostructure construction, etc., mainly targeting light absorption, charge separation and catalytic efficiency. However, the PEC efficiency improvement based on the above methods is limited and close to the bottleneck. More researchers tend to consider how to introduce external energy to significantly improve the performance of BiVO4 photoelectrodes.

[0004] As we all know, MXene composites have attracted much attention due to their metallic conductivity and high specific surface area, and have stronger light capture ability and band gap adjustment ability. MXene (Ti3C2) is often used as a titanium source in photoanodes for photoelectrocatalytic water decomposition to produce hydrogen (Journal of Energy Chemistry.2023,87,518-539). MXene can also be used as a hole transport layer to promote the transport of carriers. How to introduce MXene compounds as an intermediate layer, apply MXene composites to BiVO4 photoelectrodes, and construct a photoelectrode with a hole transport layer loaded on the photoelectrode, so as to achieve the ability to adjust charge separation and transfer to improve the performance of photoelectrochemical water decomposition and oxidation, which is of great significance to the performance improvement of BiVO4 photoelectrodes. Summary of the invention

[0005] Based on the above technical problems, the present invention provides a preparation method and application of an electrochemically activated MXene-modified BiVO4 photoelectrode, wherein the electrochemically activated MXene-modified BiVO4 photoelectrode has excellent photoelectrocatalytic activity and has excellent effect on photoelectrocatalytic water decomposition.

[0006] The present invention provides a method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, comprising the following steps:

[0007] S1. Using a BiVO4 photoelectrode as a working electrode and a solution containing MXene as an electrolyte, MXene is deposited on the BiVO4 photoelectrode by an electrophoresis method to obtain a MXene / BiVO4 composite photoelectrode;

[0008] S2. Apply bias voltage to the MXene / BiVO4 composite photoelectrode for activation, thereby obtaining the electrochemically activated MXene-modified BiVO4 photoelectrode.

[0009] Preferably, in step S1, the MXene is MXene Ti3C2.

[0010] Preferably, in step S1, in addition to using the BiVO4 photoelectrode as the working electrode, the process also includes using a saturated Ag / AgCl electrode as a reference electrode and a Pt sheet as a counter electrode.

[0011] Preferably, in step S1, the deposition voltage of the electrophoresis method is 2-5V, and the deposition time is 120-1200s.

[0012] Preferably, in step S2, the bias voltage is 0.5-0.8V, and the activation time is at least 1000s.

[0013] Preferably, in step S1, the BiVO4 photoelectrode is a BiVO4 / FTO composite photoelectrode.

[0014] Preferably, the BiVO4 / FTO composite photoelectrode is prepared by the following method:

[0015] Using the FTO substrate as the working electrode and a solution containing potassium iodide, bismuth nitrate and p-benzoquinone as the electrolyte, BiOI was deposited on the FTO substrate by an electrochemical deposition method to obtain a BiOI / FTO composite photoelectrode;

[0016] Then, a dimethyl sulfoxide solution containing vanadium acetylacetonate is drop-coated on the BiOI / FTO composite photoelectrode, and after calcination, the BiVO4 / FTO composite photoelectrode is obtained.

[0017] Preferably, the deposition voltage of the electrophoresis method is -(0.1-0.2) V, and the deposition time is 150-250 s; the calcination temperature is 430-470° C., and the time is 1-3 h.

[0018] The present invention also provides an electrochemically activated MXene-modified BiVO4 photoelectrode, which is prepared by the above-mentioned preparation method.

[0019] The present invention also proposes an application of the electrochemically activated MXene-modified BiVO4 photoelectrode in photoelectrocatalytic water decomposition.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The present invention provides a method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, using a BiVO4 photoelectrode prepared by an electrochemical deposition method and a calcination method as an electrode substrate, and then depositing MXene on the BiVO4 photoelectrode by electrophoresis, thereby realizing a method for improving the photocurrent density of BiVO4. The preparation method is simple to operate and low in cost. The BiVO4 photoelectrode is first obtained by an electrodeposition method, and then the conductivity of the MXene solution is utilized to apply a bias voltage, and after the MXene is activated, the MXene is tightly adsorbed on the BiVO4, thereby obtaining an electrochemically activated MXene-modified BiVO4 photoelectrode.

[0022] (2) The electrochemically activated MXene-modified BiVO4 photoelectrode prepared by the present invention not only improves the performance of the BiVO4 photoelectrode, but also the electrochemically activated MXene can serve as a hole transport layer to promote carrier transport, reduce the recombination rate of electrons and holes in BiVO4, and extend the life of electrons and holes; at the same time, MXene is deposited on BiVO4 to ensure the stability of BiVO4.

[0023] (3) The electrochemically activated MXene-modified BiVO4 photoelectrode prepared by the present invention for photoelectrocatalytic water splitting has potential value in the field of PEC water splitting. It is committed to deepening the research on interface engineering to improve the photoelectric properties of BiVO4, and provides a new idea for the direction of converting solar energy into clean, renewable and sustainable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the preparation process of the electrochemically activated MXene-modified BiVO4 photoelectrode of the present invention;

[0025] Figure 2 The scanning electron microscope images of the BiVO4 photoelectrode described in Comparative Example 1 of the present invention and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3, Figure (ab) is the scanning electron microscope image of the BiVO4 photoelectrode described in Comparative Example 1, and Figure (cd) is the scanning electron microscope image of the MXene / BiVO4 composite photoelectrode described in Comparative Example 3;

[0026] Figure 3 A graph showing the change in photocurrent density of the electrochemically activated MXene-modified BiVO4 photoelectrode as a function of activation time;

[0027] Figure 4 LSV diagram of the MXene / BiVO4 composite photoelectrode described in Comparative Examples 2-4 of the present invention;

[0028] Figure 5 LSV diagrams of the electrochemically activated MXene-modified BiVO4 photoelectrode described in Examples 1-3 of the present invention, the BiVO4 photoelectrode described in Comparative Example 1, and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3;

[0029] Figure 6 ABPE diagrams of the electrochemically activated MXene-modified BiVO4 photoelectrode described in Examples 1-3 of the present invention, the BiVO4 photoelectrode described in Comparative Example 1, and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3;

[0030] Figure 7 These are the XPS spectra of the electrochemically activated MXene-modified BiVO4 photoelectrode described in Example 1 of the present invention and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3. Figure (a) is the Ti 2p XPS spectrum of the electrochemically activated MXene-modified BiVO4 photoelectrode described in Example 1, and Figure (b) is the C1s XPS spectrum of the MXene / BiVO4 composite photoelectrode described in Comparative Example 3. DETAILED DESCRIPTION

[0031] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments, but it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0032] Example 1

[0033] Reference Figure 1 This embodiment provides a method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, comprising the following steps:

[0034] (1) Weigh 3.32 g of potassium iodide and add it to 50 mL of deionized water, and then allow it to fully dissolve under the action of magnetic stirring, and then slowly add a small amount of 1 M dilute nitric acid to the solution, and keep the final pH between 1.60 and 1.65; then weigh 0.970 g of bismuth nitrate pentahydrate, and then add it to the above solution to obtain an orange-red solution, and then weigh 0.498 g of p-benzoquinone and add it to the orange-red solution to form the desired deposition solution;

[0035] (2) The above-mentioned deposition solution is used as an electrolyte, the FTO substrate is used as a working electrode, the saturated Ag / AgCl electrode is used as a reference electrode, and the Pt sheet is used as a counter electrode. Electrochemical deposition is carried out in the three-electrode system. The deposition potential is -0.144 V, the deposition time is 200 s, and a BiOI film is deposited on the FTO substrate. After washing the surface with a large amount of distilled water, a BiOI / FTO composite electrode is obtained; 0.265 g of vanadium acetylacetonate is weighed and added to 5 mL of dimethyl sulfoxide. After ultrasonication for 15 min, it is dissolved to form a dimethyl sulfoxide solution containing vanadium acetylacetonate. 100 μL of the dimethyl sulfoxide solution containing vanadium acetylacetonate is drop-coated on the above-mentioned BiOI / FTO composite electrode. The obtained sample is then placed in a muffle furnace, heated at 450° C. for 2 h, taken out, and the impurities remaining on the surface are removed with a 1 M sodium hydroxide solution. After drying at room temperature, a BiVO4 / FTO composite electrode is obtained, which is a BiVO4 photoelectrode.

[0036] (3) After ultrasonicating 2.5 mL of MXene Ti3C2 solution for 10 min, 47.5 mL of deionized water was added, and ultrasonicated for another 20 min until it was completely dispersed to obtain a MXene-containing solution with a concentration of 0.05 mg / mL;

[0037] (4) The above MXene-containing solution was used as an electrolyte, the BiVO4 photoelectrode was used as a working electrode, the saturated Ag / AgCl electrode was used as a reference electrode, and the Pt sheet was used as a counter electrode. Electrochemical deposition was performed in the three-electrode system. The deposition voltage was 3 V and the deposition time was 600 s. MXene was deposited on the BiVO4 photoelectrode. The surface was washed with deionized water to remove the residual electrolyte and then dried in a vacuum oven at 60° C. for 12 h to obtain a MXene / BiVO4 composite photoelectrode.

[0038] (5) Applying a bias voltage to activate the MXene / BiVO4 composite photoelectrode, the bias voltage is 0.6 V, and the activation time is 3000 s, to obtain the electrochemically activated MXene modified BiVO4 photoelectrode, which is recorded as MXene / BVO-3000s.

[0039] Example 2

[0040] This example proposes a method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, which is specifically referred to Example 1, except that the activation time in step (5) is 6000s, recorded as MXene / BVO-6000s.

[0041] Example 3

[0042] This example proposes a method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, which is specifically referred to Example 1, except that the activation time in step (5) is 8000s, recorded as MXene / BVO-8000s.

[0043] Comparative Example 1

[0044] This comparative example proposes a method for preparing a BiVO4 photoelectrode, comprising the following steps:

[0045] (1) Weigh 3.32 g of potassium iodide and add it to 50 mL of deionized water, and then allow it to fully dissolve under the action of magnetic stirring, and then slowly add a small amount of 1 M dilute nitric acid to the solution, and keep the final pH between 1.60 and 1.65; then weigh 0.970 g of bismuth nitrate pentahydrate, and then add it to the above solution to obtain an orange-red solution, and then weigh 0.498 g of p-benzoquinone and add it to the orange-red solution to form the desired deposition solution;

[0046] (2) The above deposition solution is used as an electrolyte, the FTO substrate is used as a working electrode, the saturated Ag / AgCl electrode is used as a reference electrode, and the Pt sheet is used as a counter electrode. Electrochemical deposition is carried out in the three-electrode system. The deposition potential is -0.144 V, the deposition time is 200 s, and a BiOI film is deposited on the FTO substrate. After washing the surface with a large amount of distilled water, a BiOI / FTO composite electrode is obtained; 0.265 g of vanadium acetylacetonate is weighed and added to 5 mL of dimethyl sulfoxide. After ultrasonication for 15 min, it is dissolved to form a dimethyl sulfoxide solution containing vanadium acetylacetonate. 100 μL of the dimethyl sulfoxide solution containing vanadium acetylacetonate is drop-coated on the above BiOI / FTO composite electrode. The obtained sample is then placed in a muffle furnace, heated at 450° C. for 2 h, taken out, and the impurities remaining on the surface are removed with a 1 M sodium hydroxide solution. After drying at room temperature, a BiVO4 / FTO composite electrode is obtained, which is a BiVO4 photoelectrode, denoted as BVO.

[0047] Comparative Example 2

[0048] This comparative example proposes a method for preparing a MXene / BiVO4 composite photoelectrode, which specifically refers to Example 1, except that the deposition voltage in step (4) is 2V, and step (5) is omitted, to obtain a MXene / BiVO4 composite photoelectrode, recorded as MXene / BiVO4-2V.

[0049] Comparative Example 3

[0050] This comparative example proposes a method for preparing a MXene / BiVO4 composite photoelectrode, which specifically refers to Example 1, except that step (5) is omitted to obtain a MXene / BiVO4 composite photoelectrode, which is recorded as MXene / BiVO4-3V or MXene / BVO.

[0051] Comparative Example 4

[0052] This comparative example proposes a method for preparing a MXene / BiVO4 composite photoelectrode, which specifically refers to Example 1, except that the deposition voltage in step (4) is 4 V and step (5) is omitted, to obtain a MXene / BiVO4 composite photoelectrode, recorded as MXene / BiVO4-4V.

[0053] The BiVO4 photoelectrode described in Comparative Example 1 and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3 were characterized by scanning electron microscopy. Figure 2 shown.

[0054] Figure 2 The scanning electron microscope images of the BiVO4 photoelectrode described in Comparative Example 1 of the present invention and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3 are shown in FIG. Figure 2It can be seen that the BiVO4 photoelectrode described in Comparative Example 1 presents a worm structure, and in the MXene / BiVO4 composite photoelectrode described in Comparative Example 3, MXene is in a flake shape and is deposited on BiVO4, indicating that MXene is deposited on the surface of BiVO4.

[0055] The photoelectrode described in the embodiment or comparative example was used with a standard optical power of 100 mW / cm 2 , the PEC water splitting performance was studied under AM 1.5G simulated sunlight. In a standard three-electrode system, the electrolyte solution was a potassium borate buffer solution with a pH of 9. The test was performed by linear sweep voltammetry (LSV). The results are as follows Figure 3-5 shown.

[0056] Figure 3 The photocurrent density of the electrochemically activated MXene-modified BiVO4 photoelectrode of the present invention changes with the activation time, referring to Figure 3 It can be seen that with the increase of activation time, the photocurrent density of the electrochemically activated MXene-modified BiVO4 photoelectrode tends to be flat until it is higher than 8000s.

[0057] Figure 4 The LSV diagram of the MXene / BiVO4 composite photoelectrode described in Comparative Examples 2-4 of the present invention is shown in FIG. Figure 4 It can be seen that compared with the electrochemically activated MXene modified BiVO4 photoelectrode described in Examples 1-3, the unactivated MXene / BiVO4 composite photoelectrode in Comparative Examples 2-4 has no difference in the performance of the electrochemically activated MXene / BiVO4 composite photoelectrode as the bias voltage applied for depositing MXene increases, indicating that the bias voltage of MXene deposition has no effect on the performance of the electrochemically activated MXenee / BiVO4 composite photoelectrode, so the bias voltage range of MXene deposition can be set to 2-5V.

[0058] Figure 5 The LSV diagrams of the electrochemically activated MXene-modified BiVO4 photoelectrodes described in Examples 1-3 of the present invention, the BiVO4 photoelectrodes described in Comparative Example 1, and the MXene / BiVO4 composite photoelectrodes described in Comparative Example 3 are shown in FIG. Figure 5 It can be seen that compared with the electrochemically activated MXene modified BiVO4 photoelectrode described in Examples 1-3, the performance of the unactivated MXene / BiVO4 composite photoelectrode in Comparative Example 3 is similar to that of the BiVO4 photoelectrode described in Comparative Example 1, and the photocurrent density is about 1.72 mA / cm 2 As the activation time increases, the performance of the MXene-modified BiVO4 photoelectrode is significantly improved. After 8000s of activation, the photocurrent density of MXene / BiVO4-8000s reaches 3.9mA / cm2 .

[0059] Figure 6 ABPE diagrams of the electrochemically activated MXene-modified BiVO4 photoelectrodes described in Examples 1-3 of the present invention, the BiVO4 photoelectrodes described in Comparative Example 1, and the MXene / BiVO4 composite photoelectrodes described in Comparative Example 3, refer to Figure 6 It can be seen that with the increase of activation time, ABPE also increases significantly.

[0060] Figure 5 and Figure 6 The results show that with the introduction of MXene, the recombination of carriers is suppressed by applying bias to activate MXene, while the migration of BiVO4 holes is accelerated, and the longer the activation time, the higher the carrier transfer rate.

[0061] Figure 7 The XPS spectra of the electrochemically activated MXene-modified BiVO4 photoelectrode described in Example 1 of the present invention and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3, wherein the electrochemically activated MXene-modified BiVO4 photoelectrode after activation corresponds to the electrochemically activated MXene-modified BiVO4 photoelectrode described in Example 1, and the MXene / BiVO4 composite photoelectrode described in Comparative Example 3 before activation. The chemical structure of MXene (Ti3C2) can be determined by analyzing the Ti and C elements. Figure 7 (a) It can be seen that in the Ti 2p spectrum of the MXene / BiVO4 composite photoelectrode before activation, 3 / 2 Among them, Ti-C, Ti 2+ 、Ti 3+ The binding energies of Ti-O are 454.68, 455.28, 456.48 and 458.68 eV respectively. 1 / 2 Among them, Ti-C, Ti 2+ 、Ti 3+ The binding energies of Ti-O and Ti-O are 460.48, 460.78, 461.88 and 464.58 eV, respectively, and are accompanied by satellite peaks. The binding energy is 465.88, which is consistent with the XPS research results of previous researchers. The activated MXene-modified BiVO4 photoelectrode is significantly different from the MXene / BiVO4 composite photoelectrode before activation. 3 / 2 and Ti 2p 1 / 2 Ti-C, Ti 2+ 、Ti 3+ The peaks disappeared, and only the Ti-O peak and satellite peaks were observed. It is speculated that Ti-C, Ti 2+ 、Ti 3+ Transformed to Ti-O X , indicating the generation of new substances; refer to Figure 7(b) It can be seen that in the C1s spectrum of the MXene / BiVO4 composite photoelectrode before activation, the C1s spectrum is divided into four peaks centered at 281.65, 284.8, 286.45 and 288.35 eV, corresponding to C-Ti, CC, CH x / CO and COO, the C-Ti peak disappears after activation, which also proves that the material composition of the activated MXene-modified BiVO4 photoelectrode has undergone new changes.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an electrochemically activated MXene-modified BiVO4 photoelectrode, characterized in that: The steps include: S1. Using a BiVO4 photoelectrode as a working electrode and a solution containing MXene as an electrolyte, MXene is deposited on the BiVO4 photoelectrode by an electrophoresis method to obtain a MXene / BiVO4 composite photoelectrode; S2. Apply bias voltage to the MXene / BiVO4 composite photoelectrode for activation, thereby obtaining the electrochemically activated MXene-modified BiVO4 photoelectrode.

2. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 1, characterized in that: In step S1, the MXene is MXene Ti3C2.

3. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 1 or 2, characterized in that: In step S1, in addition to using the BiVO4 photoelectrode as the working electrode, a saturated Ag / AgCl electrode is used as a reference electrode and a Pt sheet is used as a counter electrode.

4. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 3, characterized in that: In step S1, the deposition voltage of the electrophoresis method is 2-5V, and the deposition time is 120-1200s.

5. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to any one of claims 1 to 4, characterized in that: In step S2, the bias voltage is 0.5-0.8V, and the activation time is at least 1000s.

6. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to any one of claims 1 to 5, characterized in that: In step S1, the BiVO4 photoelectrode is a BiVO4 / FTO composite photoelectrode.

7. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 6, characterized in that: The BiVO4 / FTO composite photoelectrode is prepared by the following method: Using the FTO substrate as the working electrode and a solution containing potassium iodide, bismuth nitrate and p-benzoquinone as the electrolyte, BiOI was deposited on the FTO substrate by electrodeposition to obtain a BiOI / FTO composite photoelectrode. Then, a dimethyl sulfoxide solution containing vanadium acetylacetonate is drop-coated on the BiOI / FTO composite photoelectrode, and after calcination, the BiVO4 / FTO composite photoelectrode is obtained.

8. The method for preparing the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 7, characterized in that: The deposition voltage of the electrochemical deposition method is -(0.1-0.2)V, and the deposition time is 150-250s; the calcination temperature is 430-470°C, and the time is 1-3h.

9. An electrochemically activated MXene-modified BiVO4 photoelectrode, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the electrochemically activated MXene-modified BiVO4 photoelectrode according to claim 9 in photoelectrocatalytic water decomposition.

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