Photo-anode interface layer and preparation method and application thereof

Abstract

The invention discloses a photo-anode interface layer and a preparation method and application thereof, and belongs to the technical field of material synthesis. The interface layer is composed of three elements of Fe, Ti and O, is of a cubic phase structure and comprises a multi-metal redox state. The preparation method comprises the following steps: dissolving a Fe source and a Ti source in an organic solvent according to a certain molar ratio to obtain a precursor solution for interface layer modification; the precursor solution is modified on the surface of the photo-anode in a hydrothermal treatment mode, and stable growth of an interface layer is achieved through annealing. The interface layer modification can effectively promote the separation and transfer of photogenerated charges of the photoanode, effectively improve the initial potential of a photoelectrocatalytic water decomposition reaction, and improve the photocurrent density and fill factors.

Description

Technical Field

[0001] The present application relates to a photoanode interface layer and a preparation method and application thereof, belonging to the technical field of material synthesis. Background Art

[0002] The production of green hydrogen from renewable energy is an important part of achieving the transformation of energy structure. Solar water splitting is an important route for the production of green hydrogen. Photoelectrocatalysis can realize a one-step solar self-driven water splitting process, making it possible to produce hydrogen through water splitting reactions in areas with power shortages. The solar-to-hydrogen conversion efficiency of the photoelectrocatalytic water splitting reaction is closely related to light harvesting, charge separation, and surface catalysis processes. The time scales of these three processes are mismatched, and there is serious charge recombination, which makes the efficiency of photoelectrocatalytic water splitting far from practical application. Therefore, more efficient photoelectrode materials and photoelectrocatalytic devices must be developed. The core issue is how to promote charge separation and transfer. Interface layer modification is an effective way to improve photogenerated charge separation and transfer. Yuxuan Chen et al. reported in the literature (Small 2024,2402406) that a FeOCl-modified BiVO4 photoanode at 1.23V RHE The photocurrent density under potential reached 5.23 mA cm -2 , however, the starting potential is poor, only 0.3V RHE Kan Zhang et al. introduced a black phosphorene (BP) interface layer between BiVO4 and the oxygen-generating co-catalyst in the literature (Nat. Commun. 2019, 10, 2001). The p-type BP interface layer can promote the extraction of holes in BiVO4 and prolong the hole lifetime. It can be seen that the interface layer material that matches the photoanode and promotes charge separation and transport is critical to improving the photoelectrocatalytic performance. Summary of the invention

[0003] In order to solve the problem of low efficiency in the existing technology of photoelectrocatalytic water splitting, the present application proposes a technical solution for improving the separation and transfer of photogenerated charges in the photoanode by modifying the interface layer. Multiple metal redox states are introduced through the Fe2TiO4 interface layer to promote charge separation and transfer, increase the photogenerated voltage, and thus effectively improve the performance of photoelectrocatalytic water splitting.

[0004] This application adopts the following technical solutions:

[0005] According to the first aspect of the present application, there is provided a photoanode interface layer comprising Fe2TiO4 material.

[0006] Optionally, the Fe2TiO4 material has a cubic phase structure and contains multiple metal redox states;

[0007] Optionally, the photoanode interface layer has a thickness of 8 to 10 nm.

[0008] Optionally, the photoanode interface layer is grown on a conductive substrate of the photoanode.

[0009] According to another aspect of the present application, a method for preparing the above-mentioned photoanode interface layer is provided, characterized in that it comprises the following steps:

[0010] A precursor solution containing Fe source, Ti source and organic solvent is placed in a sealed container, and then a conductive substrate is placed in the precursor solution for hydrothermal reaction, and then the conductive substrate is annealed to grow the photoanode interface layer on the surface of the conductive substrate.

[0011] The precursor solution is obtained as follows: dissolving the Fe source and the Ti source in an organic solvent, stirring for 15 to 30 minutes to mix evenly to obtain the precursor solution.

[0012] Optionally, the Fe source is selected from at least one of ferric acetate, ferric acetylacetonate, ferric citrate, ferric sulfate, ferric chloride and ferric nitrate.

[0013] Optionally, the Ti source is selected from at least one of tetrabutyl titanate, butyl titanate isopropoxide, isopropyl titanate, titanium tetraisoacetate, titanium butyl acetate, and tetraethyl titanate.

[0014] Optionally, the hydrothermal reaction is carried out in terms of molar amounts of elements in the chemical formula Fe2TiO4, and the molar ratio of the Fe source to the Ti source is 2:1.

[0015] Optionally, the organic solvent is selected from at least one of ethanol, isopropanol and n-butanol.

[0016] Optionally, the concentration of the Fe source is 2 to 60 mmol / L.

[0017] Optionally, the concentration of the Ti source is 1 to 30 mmol / L.

[0018] Optionally, the concentration of the Fe source is 6 to 20 mmol / L.

[0019] Optionally, the concentration of the Ti source is 3-10 mmol / L.

[0020] Optionally, the conductive substrate is FTO or ITO, or FTO or ITO with a light-harvesting material on the surface. The light-harvesting material may be BiVO4.

[0021] Optionally, the conditions of the hydrothermal reaction include: a hydrothermal reaction temperature of 100 to 180° C., and a hydrothermal reaction time of 2 to 12 hours.

[0022] Optionally, the annealing conditions include: an annealing temperature of 300 to 500° C., and an annealing time of 1 to 5 hours.

[0023] According to another aspect of the present application, there is also provided an application of the above-mentioned photoanode interface layer or the photoanode interface layer obtained according to the above-mentioned preparation method as a modification layer of the photoanode in photoelectrocatalytic water decomposition, pollutant degradation, and biomass oxidation reaction.

[0024] The beneficial effects of this application include:

[0025] (1) The photoanode interface layer provided in the present application and its preparation method and application have good charge transfer properties, which can significantly improve the photoelectrocatalytic water oxidation performance of the photoanode. After the BiVO4 photoanode is modified by the interface layer, the starting potential is 0.25V. RHE , at 1.23V RHE At this potential, the photocurrent density reaches 3 mA cm -2 The original BiVO4 photoanode has a starting potential of 0.38V. RHE , at 1.23V RHE At this potential, the photocurrent density is only 1.5 mA cm -2 .

[0026] (2) The photoanode based on the photoanode interface layer provided in the present application can be suitable for neutral or alkaline conditions.

[0027] (3) The raw materials required for the photoanode interface layer provided in the present application are cheap, the preparation method is simple, no large-scale equipment is required, and it is suitable for mass production.

[0028] (4) The method for preparing the photoanode interface layer provided in the present application can form a firm and uniformly covered interface layer film on the photoanode by hydrothermal treatment and annealing. The thickness of the interface layer can be adjusted by changing the concentration of the precursor solution, the hydrothermal reaction time and other parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the XRD pattern of the BiVO4\Fe2TiO4 photoanode with a Fe2TiO4 interface layer prepared on a BiVO4 substrate in Example 1.

[0030] Figure 2 This is the HRTEM image of the BiVO4\Fe2TiO4 photoanode with Fe2TiO4 interface layer prepared in Example 1.

[0031] Figure 3 This is the redox state distribution of the Fe2TiO4 interface layer prepared in Example 1.

[0032] Figure 4Linear sweep voltammetry (LSV) curves of the original BiVO4 photoanode and the BiVO4\Fe2TiO4 photoanode with a Fe2TiO4 interface layer prepared in Example 1 under AM 1.5G irradiation in potassium borate electrolyte with pH 9.

[0033] Figure 5 This is the XRD pattern of the FTO\Fe2TiO4 electrode prepared on the FTO substrate in Example 2.

[0034] Figure 6 This is the HRTEM image of the Fe2TiO4 interface layer prepared on the FTO conductive substrate in Example 2.

[0035] Figure 7 XRD patterns of BiVO4\Fe2TiO4 photoanodes with Fe2TiO4 interface layer obtained from different embodiments.

[0036] Figure 8 LSV curves of the original BiVO4 photoanode and the BiVO4\Fe2TiO4 photoanode with a Fe2TiO4 interface layer prepared by Example 4 under AM 1.5G irradiation in potassium borate electrolyte with pH 9.

[0037] Fig. 9 LSV curves of the original BiVO4 photoanode and BiVO4\Fe2TiO5 photoanode under AM1.5G irradiation in potassium borate electrolyte at pH 9. DETAILED DESCRIPTION

[0038] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0039] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0040] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0041] Example 1

[0042] The Fe2TiO4 interface layer is modified on the surface of the BiVO4 photoanode. The specific steps are as follows:

[0043] Step 1: Dissolve 10 mmol / L ferric acetylacetonate and 5 mmol / L isopropyl titanate in 50 mL isopropanol to obtain a precursor solution for interface layer modification.

[0044] Step 2: Stir the precursor solution for 20 minutes to mix evenly, transfer it to a hydrothermal reactor, place the FTO conductive substrate (FTO\BiVO4) containing the light-harvesting material BiVO4 in the hydrothermal reactor, and react in an oven at 150°C for 10 hours. Afterwards, anneal in a muffle furnace at 350°C for 3 hours to achieve stable growth of the interface layer, and obtain a photoanode interface layer.

[0045] from Figure 1 It can be seen that after the growth of Fe2TiO4 on BiVO4, the peak intensity of BiVO4 decreases, while a high-intensity peak corresponding to Fe2TiO4 appears, indicating that a BiVO4\Fe2TiO4 electrode is prepared. Figure 2 It is shown that the above steps make the thickness of the Fe2TiO4 interface layer grown on the BiVO4 surface to be about 10 nm. Figure 3 This indicates that there are multiple metal redox states in the Fe2TiO4 interface layer. Figure 4 It shows that after being modified by the Fe2TiO4 interface layer, the light response increases exponentially. The Fe2TiO4 interface layer significantly improves the performance of photoelectrocatalytic water splitting.

[0046] Example 2

[0047] Fe2TiO4 is modified on the surface of the FTO conductive glass photoanode to obtain the photoanode interface layer. The specific steps are as follows: the preparation process is basically the same as Example 1, the difference is that in step 2: the FTO conductive substrate without light-harvesting material is placed in a hydrothermal kettle, and the obtained electrode is represented by FTO\Fe2TiO4.

[0048] Figure 5 This indicates that the Fe2TiO4 interface layer can be grown directly on the FTO surface. Figure 6 This indicates that the lattice fringes match well with Fe2TiO4, indicating that Fe2TiO4 can also be directly prepared on FTO.

[0049] Example 3

[0050] The preparation process is basically the same as that of Example 1, except that in step 1: the concentration of ferric acetylacetonate is 12 mmol / L, and the concentration of isopropyl titanate is 5 mmol / L.

[0051] Figure 7 The XRD diagrams of the Fe2TiO4 interface layer obtained from different embodiments, wherein: Figure 7 a in is the XRD result of this embodiment. Figure 7 It can be seen from a in that the XRD diffraction peak of the Fe2TiO4 interface layer obtained in this embodiment is the same as that in other embodiments.

[0052] Example 4

[0053] The preparation process is basically the same as that of Example 1, except that in step 2: the hydrothermal reaction time is 5 h. Figure 7 It can be seen from b that the XRD diffraction peaks of the Fe2TiO4 interface layer obtained in this embodiment are the same as those in other embodiments.

[0054] Figure 8 LSV curves of the original BiVO4 photoanode and the BiVO4\Fe2TiO4 photoanode with Fe2TiO4 interface layer prepared in Example 4 under AM 1.5G irradiation in potassium borate electrolyte at pH 9. The Fe2TiO4 interface layer obtained in this example also significantly improves the performance of photoelectrocatalytic water splitting.

[0055] Example 5

[0056] The preparation process is basically the same as that of Example 1, except that in step 1: tetrabutyl titanate is replaced by isopropyl titanate.

[0057] from Figure 7 It can be seen from c in Figure 1 that the XRD diffraction peak of the Fe2TiO4 interface layer obtained in this embodiment is the same as that in other embodiments.

[0058] The preparation methods described in Examples 1 to 5 can all prepare a Fe2TiO4 interface layer, which can play an important role in the photoelectrocatalytic water decomposition reaction.

[0059] Comparative Example

[0060] The surface of BiVO4 is modified with Fe2TiO5, a material similar to the Fe2TiO4 interface layer. The specific preparation steps are as follows: the preparation process is basically the same as that in Example 1, except that the annealing temperature of the muffle furnace in step 2 is 550°C.

[0061] Fig. 9 LSV curves of the original BiVO4 photoanode and BiVO4\Fe2TiO5 photoanode. Fig. 9 It can be seen that after the surface of BiVO4 photoanode is modified with Fe2TiO5, the photocurrent density is greatly reduced, highlighting the important role of the multi-band energy state of Fe2TiO4 in charge transport and photoelectric performance improvement.

[0062] The present application provides an effective Fe2TiO4 interface layer and its preparation method and application. The interface layer is prepared by hydrothermal treatment and annealing, and can form a firm and uniformly covered film on the photoanode. In the photoelectrocatalytic water decomposition reaction, it shows excellent performance. After the BiVO4 photoanode is modified by the interface layer, the starting potential is 0.25V RHE , at 1.23V RHEThe photocurrent density reached 3 mA cm -2 The initial potential of the original BiVO4 photoanode is 0.38V. RHE , at 1.23V RHE At this potential, the photocurrent density is only 1.5 mA cm -2 The interface layer described in the present application has low cost, simple preparation process, no need for large-scale equipment, and is suitable for mass production.

[0063] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A photoanode interface layer, characterized in that: The photoanode interface layer includes Fe2TiO4 material.

2. The photoanode interface layer according to claim 1, characterized in that: The Fe2TiO4 material has a cubic phase structure and contains multiple metal redox states; Preferably, the thickness of the photoanode interface layer is 8-10 nm.

3. The method for preparing the photoanode interface layer according to claim 1 or 2, characterized in that: The steps include: A precursor solution containing Fe source, Ti source and organic solvent is placed in a sealed container, and then a conductive substrate is placed in the precursor solution for hydrothermal reaction, and then the conductive substrate is annealed to grow the photoanode interface layer on the surface of the conductive substrate.

4. The preparation method according to claim 3, characterized in that: The Fe source is selected from at least one of ferric acetate, ferric acetylacetonate, ferric citrate, ferric sulfate, ferric chloride, and ferric nitrate; Preferably, the Ti source is selected from at least one of tetrabutyl titanate, butyl titanate isopropoxide, isopropyl titanate, titanium tetraisoacetate, titanium butyl acetate, and tetraethyl titanate.

5. The preparation method according to claim 3, characterized in that: The organic solvent is selected from at least one of ethanol, isopropanol and n-butanol.

6. The preparation method according to claim 3, characterized in that: The concentration of the Fe source is 2 to 60 mmol / L; Preferably, the concentration of the Ti source is 1 to 30 mmol / L.

7. The preparation method according to claim 3, characterized in that: The conductive substrate is FTO or ITO.

8. The preparation method according to claim 3, characterized in that: The conditions of the hydrothermal reaction include: the temperature of the hydrothermal reaction is 100 to 180° C., and the time of the hydrothermal reaction is 2 to 12 hours.

9. The preparation method according to claim 3, characterized in that: The annealing conditions include: an annealing temperature of 300 to 500° C. and an annealing time of 1 to 5 hours.

10. Use of the photoanode interface layer according to claim 1 or 2 or the photoanode interface layer obtained according to the preparation method according to any one of claims 3 to 9 as a modification layer of the photoanode in photoelectrocatalytic water decomposition, pollutant degradation, and biomass oxidation reactions.

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