Bi2WO6 photo-anode regulated and controlled by carrier transport layer and preparation method of Bi2WO6 photo-anode

Abstract

The invention relates to the field of photoelectrochemistry. More specifically, the invention relates to a Bi2WO6 photo-anode regulated and controlled by a carrier transport layer and a preparation method of the Bi2WO6 photo-anode. According to the Bi2WO6 photoanode regulated and controlled by the carrier transport layer and the preparation method of the Bi2WO6 photoanode, the carrier transport layer is adopted to modify the conductive substrate, and compared with a pure Bi2WO6 photoanode, the Bi2WO6 photoanode has better light absorption capacity.

Description

Technical Field

[0001] The present invention relates to the field of photoelectrochemistry, and more specifically, to a Bi2WO6 photoanode regulated by a carrier transport layer and a preparation method thereof. Background Art

[0002] Photocatalytic water splitting to produce hydrogen is considered to be an effective way to produce hydrogen in a green way and has always attracted much attention. In recent years, photocatalytic fuel cell (PFC) technology has also developed rapidly. PFC can be widely used in solar water splitting, environmental remediation, energy recovery and other fields, and is of great significance for sustainable development and global carbon neutrality. Among them, the selection of photoelectrode materials is a key link in the construction of the PFC system. The efficiency of PFC can be effectively improved by strategies such as improving the visible light utilization rate of photoelectrode materials, improving the transmission efficiency of photogenerated carriers, and suppressing the recombination efficiency of photogenerated electron-hole pairs.

[0003] Bismuth tungstate (Bi2WO6) is a non-toxic, harmless and environmentally friendly bismuth-based material with a special layered structure consisting of [WO4] 2- Octahedron and [Bi2O2] 2+ Layer composition, and has been widely used in CO2 reduction, hydrogen production and antibiotic degradation. Although Bi2WO6 can show certain photocatalytic activity under visible light, pure Bi2WO6 still has defects such as narrow visible light response range and high recombination rate of photogenerated carriers, which seriously limit its application in the field of photocatalysis and hinder the industrial application of photocatalytic technology. Therefore, an electron transport layer is used to transfer and extract the photogenerated electrons excited on the photoelectrode, while blocking holes, so as to improve the efficient transmission of photogenerated carriers.

[0004] (1) Existing photoanode preparation technologies are mostly physical preparation processes, first preparing powdered photocatalysts, and then preparing photoelectrodes by spin coating, scraping, dipping, etc. The photoelectrodes prepared by this method are immersed in the electrolyte for a long time, and the photocatalysts are easy to fall off, and the preparation process is cumbersome;

[0005] (2) The interface contact between the conductive substrate and the photocatalyst and the efficiency of photogenerated carrier migration are not considered in the existing photoelectrode preparation process;

[0006] (3) The existing seed layer method for improving the interface contact between the conductive substrate and the catalyst is mostly used in perovskite solar cells, and is rarely used in photocatalytic fuel cells;

[0007] (4) Existing bismuth tungstate is mostly prepared as powder nano-photocatalysts, and it is rare to grow it directly on a conductive substrate. Most of them are used for photodegradation of pollutants, and it is rarely used for decomposing water to produce hydrogen. Summary of the invention

[0008] The purpose of the present invention is to provide a Bi2WO6 photoanode regulated by a carrier transport layer and a preparation method thereof. After the conductive substrate is modified by the carrier transport layer, it has better light absorption ability than the pure Bi2WO6 photoanode.

[0009] In order to achieve these purposes and other advantages according to the present invention, a method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer is provided, comprising the following steps:

[0010] S1, covering the surface of FTO conductive glass with a carrier transport layer for standby use;

[0011] S2, prepare Bi2WO6 precursor solution for standby use;

[0012] S3. Place the FTO conductive glass treated in S1 in the Bi2WO6 precursor solution prepared in S2, react at a temperature of 140-180°C for 18-24h, and then naturally cool to room temperature. Then, use deionized water and ethanol to clean the surface of the FTO conductive glass respectively, and dry the FTO conductive glass. After drying, calcine at a temperature of 450-550°C for 0.5-2h to obtain the Bi2WO6 photoanode.

[0013] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, the preparation of the Bi2WO6 precursor solution in S2 specifically includes:

[0014] The Bi(NO3)3·5H2O solution and the Na2WO4·2H2O solution are added into ethylene glycol and stirred until the solution becomes clear, thereby obtaining the Bi2WO6 precursor solution.

[0015] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, in S3, the conductive surface of the FTO conductive glass is placed facing downward in the Bi2WO6 precursor solution prepared in S2.

[0016] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, the carrier transport layer described in S1 is a TiO2 seed layer.

[0017] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, when the TiO2 seed layer is covered on the surface of the FTO conductive glass in S1, the method specifically includes:

[0018] S1.1, tetrabutyl titanate and ethanol solution are mixed in a volume ratio of 1:60, and stirred and ultrasonically treated in sequence to obtain a first solution;

[0019] S1.2, placing the FTO conductive glass in the first solution obtained in S1.1, placing it in an oven at 70°C for 30 minutes, taking out the FTO conductive glass and slowly rinsing it with anhydrous ethanol;

[0020] S1.3. Place the FTO conductive glass rinsed in S1.2 in an air atmosphere at 450°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the TiO2 seed layer is obtained.

[0021] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, the carrier transport layer described in S1 is a SnO2 seed layer.

[0022] Furthermore, in the method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, when the SnO2 seed layer is covered on the surface of the FTO conductive glass in S1, it specifically includes:

[0023] S1.1, mix the SnCl2 solution and IPA, stir evenly, and let stand for 24 hours to obtain a second solution;

[0024] S1.2, using the spin coating method, the second solution obtained in S1.1 is evenly coated on the FTO conductive glass at a speed of 4000 r / min for 30 seconds, and then placed on a hot plate at 150°C and heated for 30 minutes;

[0025] S1.3. Place the FTO conductive glass treated in S1.2 in an air atmosphere at 500°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the SnO2 seed layer is obtained.

[0026] A Bi2WO6 photoanode with carrier transport layer regulation is prepared by adopting the preparation method.

[0027] The beneficial effects of the present invention are:

[0028] 1. The carrier transport layer of the present invention provides a good mass transfer channel for the transport of photogenerated carriers at the interface between the photocatalyst and the conductive substrate, thereby improving the photocatalytic performance of the entire system.

[0029] 2. The present invention can solve the problem of inconvenience in recovering organic pollutants in wastewater treated with photocatalyst powder.

[0030] 3. The Bi2WO6 photoanode regulated by the carrier transport layer provided by the present invention has better light absorption capacity than pure photocatalyst after the conductive substrate is modified by the carrier transport layer.

[0031] 4. The Bi2WO6 photoanode regulated by the carrier transport layer provided by the present invention can be used in photoelectrocatalytic systems and photocatalytic fuel cells for the removal of organic pollutants, heavy metals, microplastics and other pollutants in wastewater, and can also be used in photoelectrocatalytic systems for the electrolysis of water to produce hydrogen and oxygen

[0032] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the JV curves of the Bi2WO6 photoanode of experimental groups 1-3;

[0034] Figure 2 Schematic diagram of the photocatalytic degradation experimental results of the PFC system constructed by the photoanode of experimental groups 1-3 using tetracycline as the target reactant. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0036] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] Example 1

[0038] An embodiment of the present invention provides a method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, comprising the following steps:

[0039] S1, covering the TiO2 seed layer on the surface of FTO conductive glass for standby use;

[0040] When the TiO2 seed layer is covered on the surface of the FTO conductive glass, the method specifically comprises:

[0041] S1.1, tetrabutyl titanate and ethanol solution are mixed in a volume ratio of 1:60, and stirred and ultrasonically treated in sequence to obtain a first solution;

[0042] S1.2, placing the FTO conductive glass in the first solution obtained in S1.1, placing it in an oven at 70°C for 30 minutes, taking out the FTO conductive glass and slowly rinsing it with anhydrous ethanol;

[0043] S1.3. Place the FTO conductive glass rinsed in S1.2 in an air atmosphere at 450°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the TiO2 seed layer is obtained.

[0044] S2, prepare Bi2WO6 precursor solution for standby use;

[0045] The preparation of Bi2WO6 precursor solution in S2 specifically includes:

[0046] Adding Bi(NO3)3·5H2O solution and Na2WO4·2H2O solution into ethylene glycol and stirring until clear, thereby obtaining the Bi2WO6 precursor solution;

[0047] S3. Place the conductive surface of the FTO conductive glass treated in S1 downward in the Bi2WO6 precursor solution prepared in S2, react at a temperature of 140-180°C for 18-24 hours, cool naturally to room temperature, clean the surface of the FTO conductive glass with deionized water and ethanol respectively, and dry the FTO conductive glass. After drying, calcine at a temperature of 450-550°C for 0.5-2 hours to obtain the Bi2WO6 photoanode.

[0048] Example 2

[0049] An embodiment of the present invention provides a method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, comprising the following steps:

[0050] S1, covering the surface of FTO conductive glass with a SnO2 seed layer for later use;

[0051] When the SnO2 seed layer is covered on the surface of the FTO conductive glass, the method specifically includes:

[0052] S1.1, mix the SnCl2 solution and IPA, stir evenly, and let stand for 24 hours to obtain a second solution;

[0053] S1.2, using the spin coating method, the second solution obtained in S1.1 is evenly coated on the FTO conductive glass at a speed of 4000 r / min for 30 seconds, and then placed on a hot plate at 150°C and heated for 30 minutes;

[0054] S1.3. Place the FTO conductive glass treated in S1.2 in an air atmosphere at 500°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the SnO2 seed layer is obtained.

[0055] S2, prepare Bi2WO6 precursor solution for standby use;

[0056] The preparation of Bi2WO6 precursor solution in S2 specifically includes:

[0057] Adding Bi(NO3)3·5H2O solution and Na2WO4·2H2O solution into ethylene glycol and stirring until clear, thereby obtaining the Bi2WO6 precursor solution;

[0058] S3. Place the conductive surface of the FTO conductive glass treated in S1 downward in the Bi2WO6 precursor solution prepared in S2, react at a temperature of 140-180°C for 18-24 hours, cool naturally to room temperature, clean the surface of the FTO conductive glass with deionized water and ethanol respectively, and dry the FTO conductive glass. After drying, calcine at a temperature of 450-550°C for 0.5-2 hours to obtain the Bi2WO6 photoanode.

[0059] Test example

[0060] Experimental group 1 adopts the method of Example 1 to prepare Bi2WO6 photoanode grown on TiO2 seed layer modified (Tpre-FTO / BWO), experimental group 2 adopts the method of Example 2 to prepare Bi2WO6 photoanode grown on SnO2 seed layer modified (Spre-FTO / BWO), and experimental group 3 uses Bi2WO6 photoanode that has not been regulated by carrier transport layer (pure BWO).

[0061] like Figure 1 As shown, by comparing the JV curves of the Bi2WO6 photoanodes of the above experimental groups 1-3, it can be seen that the photocurrent density of Tpre-FTO / BWO in experimental group 1 and Spre-FTO / BWO in experimental group 2 are significantly improved compared with the pure BWO in experimental group 3. Among them, the photocurrent density of Spre-FTO / BWO in experimental group 2 is also significantly higher than that of Tpre-FTO / BWO in experimental group 1. From the above content, it can be seen that the pretreatment of the TiO2 seed layer and the SnO2 seed layer can significantly reduce the energy loss caused by the charge transport process, provide higher conductivity, and thus accelerate the migration of photogenerated electrons. Among them, the pretreatment of the SnO2 seed layer is better than the pretreatment of the TiO2 seed layer in reducing the energy loss caused by the charge transport process.

[0062] like Figure 2As shown, the PFC system constructed by the photoanode of the above test groups 1-3 (Tpre-FTO / BWO-Pt PFC, Spre-FTO / BWO-Pt PFC and pure BWO-Pt PFC) was subjected to photocatalytic degradation experiments with tetracycline as the target reactant. After comparing the photodegradation of tetracycline hydrochloride by the pure BWO-Pt PFC, Tpre-FTO / BWO-Pt PFC and Spre-FTO / BWO-Pt PFC systems, it was found that the PFC system constructed by the two photoanodes with seed layer pretreatment had a higher degradation efficiency of tetracycline within 4 hours. It can be seen that the photocatalytic performance of the Spre-FTO / BWO-Pt PFC system has been greatly improved, and the maximum degradation efficiency is 38.02%.

[0063] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer, characterized in that: The following steps are involved: S1, covering the surface of FTO conductive glass with a carrier transport layer for standby use; S2, prepare Bi2WO6 precursor solution for standby use; S3. Place the FTO conductive glass treated in S1 in the Bi2WO6 precursor solution prepared in S2, react at a temperature of 140-180°C for 18-24h, and then naturally cool to room temperature. Then, use deionized water and ethanol to clean the surface of the FTO conductive glass respectively, and dry the FTO conductive glass. After drying, calcine at a temperature of 450-550°C for 0.5-2h to obtain the Bi2WO6 photoanode.

2. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 1, characterized in that: The preparation of Bi2WO6 precursor solution in S2 specifically includes: The Bi(NO3)3·5H2O solution and the Na2WO4·2H2O solution are added into ethylene glycol and stirred until the solution becomes clear, thereby obtaining the Bi2WO6 precursor solution.

3. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 1, characterized in that: In S3, the conductive surface of the FTO conductive glass is placed facing downward in the Bi2WO6 precursor solution prepared in S2.

4. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 1, characterized in that: The carrier transport layer described in S1 is a TiO2 seed layer.

5. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 4, characterized in that: When the TiO2 seed layer is covered on the surface of the FTO conductive glass in S1, it specifically includes: S1.1, tetrabutyl titanate and ethanol solution are mixed in a volume ratio of 1:60, and stirred and ultrasonically treated in sequence to obtain a first solution; S1.2, placing the FTO conductive glass in the first solution obtained in S1.1, placing it in an oven at 70°C for 30 minutes, taking out the FTO conductive glass and slowly rinsing it with anhydrous ethanol; S1.

3. Place the FTO conductive glass rinsed in S1.2 in an air atmosphere at 450°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the TiO2 seed layer is obtained.

6. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 1, characterized in that: The carrier transport layer described in S1 is a SnO2 seed layer.

7. The method for preparing a Bi2WO6 photoanode regulated by a carrier transport layer according to claim 6, characterized in that: When the SnO2 seed layer is covered on the surface of the FTO conductive glass in S1, it specifically includes: S1.1, mix the SnCl2 solution and IPA, stir evenly, and let stand for 24 hours to obtain a second solution; S1.2, using the spin coating method, the second solution obtained in S1.1 is evenly coated on the FTO conductive glass at a speed of 4000 r / min for 30 seconds, and then placed on a hot plate at 150°C and heated for 30 minutes; S1.

3. Place the FTO conductive glass treated in S1.2 in an air atmosphere at 500°C and anneal at a temperature drop rate of 2°C / min for 30 minutes. After cooling, the FTO conductive glass modified with the SnO2 seed layer is obtained.

8. A Bi2WO6 photoanode regulated by a carrier transport layer, characterized in that: The method is prepared according to any one of claims 1 to 6.

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