Photoelectric structure and dual-photoelectrode photoelectrochemical cell

Abstract

The invention discloses a photoelectric structure and a dual-photoelectrode photoelectrochemical cell. The photoelectric structure comprises a transparent conductive substrate, micron-sized micro-column arrays formed on the substrate, and mesoporous membranes formed on the substrate and located between the micro-column arrays. A photocatalyst is arranged on the micro-column array, the mesoporous membrane is made of a mesoporous material for absorbing light with partial wavelength in a full spectrum, and at least partial light penetrates through the mesoporous membrane. The micro-column array is adopted to counteract stress generated in the mesoporous membrane in the high-temperature calcination process, so that the mesoporous membrane is kept complete, and the high-loading-capacity mesoporous membrane is efficiently prepared. The photo-anode has high light transmittance and can transmit more light to the photo-cathode behind the photo-anode, so that the utilization rate of light energy is improved. The mesoporous material has a high specific surface area, can provide more reaction active sites, and improves the photoelectrochemical properties of the mesoporous material. The photoanode and the photocathode do not need to be staggered, the cell structure is simple, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrochemical cells, and in particular to a photoelectric structure and a dual-photoelectrode photoelectrochemical cell. Background Art

[0002] As a device that drives electrochemical reactions through light energy, photoelectrochemical cells have a wide range of applications in the fields of photocatalytic degradation of pollutants while generating electricity, photoelectric reduction of carbon dioxide, and photoelectric hydrogen production. It uses photoelectrodes to convert solar energy into electrical energy or chemical energy, thus realizing the utilization of solar energy. Secondly, the photocatalysts used to prepare photoelectrodes are usually inexpensive semiconductors, which reduces the cost of the battery. In addition, the operating conditions are simple and the products are pollution-free. Photoelectrochemical cells have good application prospects. In order to further improve their light energy utilization and reduce costs, semiconductor photocatalysts are used at both the cathode and anode, thus proposing a dual-photoelectrode photoelectrochemical cell.

[0003] To adapt to the single-sided illumination operating conditions of actual application scenarios, the dual-photoelectrode photoelectrochemical cell uses a staggered arrangement of the cathode and anode to avoid light obstruction. This staggered arrangement of the cathode and anode complicates the cell structure, and the increased spacing between the cathode and anode increases the mass transfer distance. Furthermore, the area receiving illumination remains unchanged, and the light energy utilization rate cannot be effectively improved. As a result, the performance of the dual-photoelectrode photoelectrochemical cell has not improved as expected, hindering its large-scale application. Summary of the Invention

[0004] Based on this, it is necessary to provide a photoelectric structure and a dual-photoelectrode photoelectrochemical cell to address the problem that in the existing dual-photoelectrode photoelectrochemical cell, under the operating conditions of single-sided lighting, the anode and cathode are placed alternately, resulting in a complex cell structure and the inability to effectively improve the utilization rate of light energy.

[0005] A photovoltaic structure comprising:

[0006] Transparent conductive substrate;

[0007] A micro-pillar array of micrometer scale is formed on the substrate, and a photocatalyst is provided on the micro-pillar array;

[0008] A mesoporous membrane is formed on the substrate and located between the microcolumn arrays. The mesoporous membrane is made of a mesoporous material that absorbs light of a portion of wavelengths in the full spectrum, so that at least a portion of the light passes through the mesoporous membrane.

[0009] In the above-mentioned photoelectric structure, the mesoporous membrane is made of a mesoporous material with a high specific surface area, which can provide more reactive sites and improve its photoelectrochemical performance. The mesoporous membrane has a higher light transmittance than the membrane formed by the accumulation of traditional nanoparticles. Therefore, the mesoporous membrane has good light transmittance, and the photoanode made of the photoelectric structure has a high light transmittance. In addition, a micropillar array is first formed on the substrate, and then the mesoporous sol is coated on the micropillar array area on the substrate, and the mesoporous membrane is prepared by combining the multi-step evaporation-induced self-assembly method. The micropillar array is interspersed in the mesoporous membrane to support the mesoporous membrane, offsetting the bending stress generated by the shrinkage of the mesoporous membrane due to the removal of volatile substances in the mesoporous membrane during the high-temperature calcination process, as well as the grain growth in the mesoporous membrane and the mutual extrusion stress, thereby avoiding the breakage and shedding of the mesoporous membrane, keeping the mesoporous membrane intact, and realizing the efficient preparation of high-load mesoporous membranes, ensuring the molding quality of the photoelectric structure.

[0010] In one embodiment, the substrate is made of a transparent conductive material.

[0011] In one embodiment, the base includes a transparent substrate and a conductive film disposed on a surface of the substrate.

[0012] In one embodiment, the size of the micropillar array is 1 μm-100 μm; and / or

[0013] The spacing between the micro-pillar arrays is 1 μm-100 μm.

[0014] In one embodiment, the micropillar array is arranged in sequence along a first direction and a second direction perpendicular to each other, and the first direction and the second direction constitute the surface of the substrate.

[0015] In one embodiment, the micropillar array is a prism, a cylinder, a pyramid or a cone.

[0016] In one embodiment, the photocatalyst is a sulfide photocatalytic material or a metal oxide photocatalytic material.

[0017] In one embodiment, the thickness of the mesoporous membrane is smaller than the height of the micropillar array.

[0018] In one embodiment, the mesoporous material includes TiO2, WO3 or ZnO.

[0019] A dual-photoelectrode photoelectrochemical cell comprises: a battery shell, and a photoanode and a photocathode arranged opposite to each other in the battery shell, wherein the photoanode comprises any one of the above-mentioned photoelectric structures.

[0020] In this dual-photoelectrode photoelectrochemical cell, because the photoanode is constructed using the aforementioned photoelectric structure and has high light transmittance, the photoanode and photocathode can be positioned relative to each other. When external light strikes the photoanode, at least some of the light passes through the mesoporous membrane and strikes the photocathode. This eliminates the need for staggered placement of the photoanode and photocathode, simplifying the cell structure and significantly improving light energy utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0022] Figure 1 is a schematic diagram of an optoelectronic structure in one embodiment;

[0023] Figure 2 Schematic diagram of a dual-photoelectrode photoelectrochemical cell in one embodiment.

[0024] Reference numerals:

[0025] 10-photoelectric structure, 11-substrate, 12-micropillar array, 13-mesoporous membrane, 20-dual-photoelectrode photoelectrochemical cell, 21-cell housing, 211-anode cover, 212-cathode cover, 213-cell chamber, 22-photoanode, 23-photocathode, 24-light-punching hole, 25-electrode hole. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] See also Figure 1 In one embodiment, the optoelectronic structure 10 includes a transparent conductive substrate 11 , a micropillar array 12 and a mesoporous film 13 .

[0030] The substrate 11 is generally a sheet-like structure, and its specific structure is not fixed and is adjusted for suitability according to the specific design structure of the battery. The substrate 11 can be a narrow strip or long strip structure, or can also be made into a square or circular shape, etc. A micron-sized micropillar array 12 is formed on the substrate 11. The micropillar array 12 is provided with a photocatalyst so that light irradiated by the micropillar array 12 can be absorbed and utilized. A mesoporous membrane 13 is formed on the substrate 11 and is located between the micropillar array 12. The mesoporous membrane 13 is made of a mesoporous material that absorbs light of a portion of the wavelengths in the full spectrum, allowing at least part of the light to pass through the mesoporous membrane 13.

[0031] Mesoporous membrane 13 is made of a mesoporous material with a high specific surface area, providing more reactive sites and improving photoelectrochemical performance. Mesoporous membranes have higher light transmittance than films made of traditional nanoparticles. Therefore, mesoporous membrane 13 exhibits excellent light transmittance, and the photoelectrode formed from photoelectric structure 10 exhibits high light transmittance.

[0032] When preparing the mesoporous membrane 13 by the traditional method, the removal of volatile substances in the mesoporous membrane 13 during the high-temperature calcination process, the bending stress generated by the shrinkage of the mesoporous membrane 13, and the growth of grains in the mesoporous membrane 13 will generate stress, which will cause the mesoporous membrane 13 to break and detach, making it difficult to efficiently prepare a high-load mesoporous membrane 13.

[0033] Therefore, in this solution, a micropillar array 12 is first formed on a substrate 11, and then a mesoporous sol is coated on the micropillar array 12 area on the substrate 11, and a mesoporous membrane 13 loaded with the micropillar array 12 is prepared by combining a multi-step evaporation-induced self-assembly method. The micropillar array 12 is interspersed in the mesoporous membrane 13 to support the mesoporous membrane 13, offsetting the bending stress generated by the removal of volatile substances in the mesoporous membrane 13 and the shrinkage of the mesoporous membrane 13 during high-temperature calcination, as well as the extrusion stress between the grains growing in the mesoporous membrane 13, thereby preventing the mesoporous membrane 13 from breaking and falling off, and keeping the mesoporous membrane 13 intact. The smaller the size and spacing of the micropillar array 12, the better the effect of supporting the mesoporous membrane 13 to offset the stress. By loading the mesoporous membrane 13 with the micropillar array 12, a high-load mesoporous membrane 13 can be efficiently prepared to ensure the molding quality of the optoelectronic structure 10.

[0034] In one embodiment, the substrate 11 is transparent and conductive, and can be made of a transparent conductive material. For example, the substrate 11 can be made of conductive glass, indium tin oxide (ITO), aluminum zinc oxide, tin oxide (FTO), silver nanowires, graphene, etc. In this embodiment, the substrate 11 is made of conductive glass.

[0035] Of course, in other embodiments, the substrate 11 may also be transparently conductive using other methods. Specifically, the substrate 11 includes a transparent substrate and a conductive film disposed on the substrate surface. The conductive film is made of a transparent conductive material, which can reduce the cost of the substrate 11. For example, the substrate can be made of transparent glass, and then the conductive film is formed on the substrate surface using a coating such as indium tin oxide or graphene.

[0036] In one embodiment, the size of the micropillar array 12 is 1 μm-100 μm. The spacing between the micropillar arrays 12 is 1 μm-100 μm. The size and spacing of the micropillar arrays 12 can be the same or different.

[0037] Optionally, the spacing between the micropillar arrays 12 can be made larger than the size of the micropillar arrays 12 , thereby increasing the illumination area of the optoelectronic structure 10 and improving light energy utilization while ensuring that the micropillar arrays 12 offset the stress effect of the mesoporous film 13 .

[0038] In one embodiment, the smaller the size and spacing of the micropillar array 12, the better the stress-offsetting effect of the supporting mesoporous membrane 13. Therefore, the size and spacing of the micropillar array 12 are preferably 1 μm to 50 μm. Specifically, the size and spacing of the micropillar array 12 can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, or any other value within the range of 1 μm to 50 μm.

[0039] In one embodiment, when substrate 11 is a plate-like structure, micropillar array 12 is sequentially arranged along a first and second perpendicular direction, where the first and second directions constitute the surface of the substrate. A rectangular array of micropillar array 12 ensures uniform distribution of micropillar array 12 on plate-like substrate 11, thereby ensuring uniform support for mesoporous membrane 13 and ensuring the quality of the formation of mesoporous membrane 13.

[0040] In one embodiment, the micropillar array 12 can be made directly from a photocatalyst, or the micropillar array 12 can be pre-formed on the substrate 11, and then the photocatalyst is coated or plated on the micropillar array 12. The micropillar array 12 is generally a columnar structure, and the micropillar array 12 can be selected to be a prism, a cylinder, a pyramid, or a cone. The pillars of the micropillar array 12 can all be pillars of a uniform shape. The micropillar array 12 can also be designed with different pillar shapes in different areas. In this embodiment, the micropillar array 12 is a rectangular parallelepiped.

[0041] In one embodiment, the photocatalyst can be a sulfide-type photocatalytic material or a metal oxide photocatalytic material. Specifically, CdS, ZnS and MoS2 are representative materials of sulfide in the application of photocatalysis. They have adjustable energy bands. When they change from multilayer to single layer, their band gap width becomes wider, and the optical and electrical properties also change. Metal oxide photocatalytic materials include TiO2, Fe2O3, WO3, ZnO, Cu2O, SnO2 and BiVO4, etc. Among them, TiO2 is favored due to its stable chemical properties, high catalytic activity, low price, non-toxicity and pollution-free, and is the most studied photocatalyst today.

[0042] On the basis of the above embodiment, the photocatalyst on the micro-pillar array 12 further adopts a photocatalyst that mainly absorbs high-energy ultraviolet light, such as TiO2, WO3, etc. Specifically in this embodiment, the photocatalyst on the micro-pillar array 12 is TiO2.

[0043] In one embodiment, mesoporous membrane 13 also has a micrometer-level thickness, but its thickness is less than the height of micropillar array 12, allowing micropillar array 12 to protrude from the surface of mesoporous membrane 13, allowing the photocatalyst to absorb light and excite electron-hole pairs. Specifically, the thickness of mesoporous membrane 13 should be less than or equal to 1 / 2 the height of micropillar array 12, preferably 1 / 5 to 1 / 3 the height of micropillar array 12.

[0044] In one embodiment, the mesoporous material of mesoporous membrane 13 is made of a photocatalyst that absorbs a portion of the full spectrum of light wavelengths, allowing some light to pass through the mesoporous membrane. Specifically, the photocatalyst of mesoporous membrane 13 is similar to the photocatalyst on micropillar array 12, primarily absorbing high-energy ultraviolet light to allow visible light to pass through mesoporous membrane 13. In one embodiment, the mesoporous material includes TiO2, WO3, or ZnO. In this embodiment, the mesoporous material is TiO2.

[0045] Of course, in other embodiments, the photocatalyst of the mesoporous film 13 and the photocatalyst on the micropillar array 12 may be different, and the photocatalyst of the mesoporous film 13 and the photocatalyst on the micropillar array 12 absorb light of different wavelengths.

[0046] In one embodiment, the steps of an exemplary process for preparing the optoelectronic structure 10 are as follows:

[0047] A silicon wafer template with a micropore array photoresist film is prepared by photolithography, and then it is molded with liquid silicone to obtain a silicone template with a micropillar array 12. Holes are punched outside the micropillar array 12 area of the silicone template, and the silicone template is attached to the cleaned conductive glass. The two are bonded to obtain a mesh microchannel.

[0048] The microchannel is placed on a heating plate, and the model wax is placed at the microchannel inlet. Once the model wax melts, a micropump connected to the microchannel outlet pumps the wax into the microchannel. Once the wax fills the microchannel, the microchannel is removed from the heating plate to allow the wax to cool and solidify. The silicone template is then removed to create a wax film with a micropore array on the conductive glass.

[0049] TiO2 nanoparticles are dispersed in ethanol to obtain a TiO2 dispersion. The conductive glass with the wax film is placed in an air plasma environment to make the wax film hydrophilic, ensuring that the TiO2 dispersion can more easily enter the micropores of the wax film.

[0050] A TiO2 dispersion is applied to the wax film surface using a soft brush, allowing the dispersion to enter the micropores. Once the ethanol evaporates, the TiO2 is deposited in the micropores. Repeat the application of the dispersion until the TiO2 completely fills the micropores. Excess TiO2 on the wax film surface is then wiped off with a damp, dust-free paper. Finally, the film is calcined in a tube furnace, where the wax film pyrolyzes into gases that are removed, and the TiO2 sinters onto the conductive glass, forming a TiO2 micropillar array. 12

[0051] A silicone gasket is placed on the conductive glass surrounding the TiO2 micropillar array 12. Uncured siloxane oligomers in the silicone gasket diffuse and transfer to the surface. After the silicone gasket is removed, they remain on the conductive glass, making it hydrophobic. An appropriate amount of mesoporous TiO2 sol is applied to the micropillar array 12 area. Because the surrounding conductive glass is hydrophobic, the sol is confined to the micropillar array 12 area, forming droplets. After evaporation-induced self-assembly, the conductive glass is placed on a hot plate for thermal stabilization.

[0052] The above-mentioned process of coating the mesoporous TiO2 sol until it is thermally stable is repeated multiple times, and calcination is performed after the last evaporation-induced self-assembly to obtain a mesoporous TiO2 film optoelectronic structure 10 with a TiO2 microcolumn array 12.

[0053] It is understood that in other embodiments, the micropillar array 12 can be formed on the substrate 11 by other processes. For example, the micropillar array 12 can be prepared on quartz glass by laser etching, wet etching, or focused ion beam etching, and then coated with indium tin oxide (ITO) or fluorine-doped tin oxide (FTO) to make it conductive, thereby obtaining a transparent and conductive micropillar array 12 substrate 11 for supporting the mesoporous film 13.

[0054] See also Figure 2 The present invention also provides a dual-photoelectrode photoelectrochemical cell 20, comprising a battery housing 21 and a photoanode 22 and a photocathode 23 arranged opposite to each other in the battery housing 21, wherein the photoanode 22 comprises the above-mentioned photoelectric structure 10.

[0055] Because photoanode 22 is constructed using the aforementioned photovoltaic structure 10, it exhibits high light transmittance, allowing it to be positioned relative to photocathode 23. When external light strikes photoanode 22, at least some of it passes through mesoporous membrane 13 and strikes photocathode 23. The photovoltaic structure 10 and photocathode 23 do not need to be staggered, simplifying the battery structure and significantly improving light energy utilization.

[0056] In one embodiment, the battery housing 21 includes an anode cover plate 211, a cathode cover plate 212, and a battery chamber 213. The battery chamber 213 is disposed between the anode cover plate 211 and the cathode cover plate 212. The photovoltaic structure 10 is located between the anode cover plate 211 and the battery chamber 213. The photocathode 23 is located between the battery chamber 213 and the cathode cover plate 212. A light hole 24 is provided on the anode cover plate 211 to allow external light to enter the battery. Opposing electrode holes 25 are provided on opposite sides of the battery chamber 213 for positioning the photoanode 22 and photocathode 23 relative to each other.

[0057] When the photoelectrochemical cell is in operation, light is irradiated from the anode side. The light passes through the light-perforated hole 24 on the anode cover plate 211 and irradiates the photoanode 22. After passing through the conductive glass, the ultraviolet light is absorbed by the micropillar array 12 and the mesoporous membrane 13 on the photoanode 22, exciting electron-hole pairs. Visible light passes through the mesoporous membrane 13. The visible light that passes through the mesoporous membrane 13 passes through the cell chamber 213 and irradiates the photocathode 23 placed opposite the photoanode 22, exciting electron-hole pairs. The holes generated on the photoanode 22 have strong oxidizing properties and participate in the oxidation reaction at the photoanode 22. The electrons are transmitted to the photocathode 23 through the external circuit, recombining with the holes generated on the photocathode 23 and forming a current in the external circuit. At the same time, the electrons generated on the photocathode 23 participate in the reduction reaction.

[0058] In one embodiment, the photocatalyst in the mesoporous membrane 13 and the photocatalyst in the micropillar array 12 primarily absorb high-energy ultraviolet light. Therefore, the photocathode 23 utilizes a photocatalyst that absorbs both ultraviolet light and lower-energy visible light. Specifically, the photocatalyst used in the photocathode 23 may be CuO, Cu2O, CsSb, or the like. Specifically, in this embodiment, the photocatalyst used in the photocathode 23 is CuO.

[0059] In one embodiment, the steps of an exemplary process for preparing the photocathode 23 are as follows:

[0060] A predetermined mass of CuO nanoparticles and Nafion solution was weighed and added to an ethanol solution. The mixture was stirred thoroughly to obtain a CuO dispersion. The CuO dispersion was sprayed onto a conductive glass substrate using an airbrush, controlling the spraying area and CuO loading. The CuO photocathode 23 was then dried.

[0061] The above-mentioned dual-photoelectrode photoelectrochemical cell 20 and its photoelectric structure 10 use a micropillar array 12 to offset the stress generated in the mesoporous membrane 13 during the high-temperature calcination process, so that the mesoporous membrane 13 remains intact, and a high-load mesoporous membrane 13 is efficiently prepared. The photoanode 22 has a high light transmittance and can transmit more light to the photocathode 23 behind it, thereby improving the photoelectrochemical performance of the photocathode 23. The mesoporous membrane has a high specific surface area and can provide more reaction active sites, thereby improving its photoelectrochemical performance. The photoanode 22 and the photocathode 23 do not need to be staggered, the battery structure is simple, and the cost is reduced.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A photovoltaic structure, characterized in that: include: Transparent conductive substrate; A micro-pillar array of micrometer scale is formed on the substrate, and a photocatalyst is provided on the micro-pillar array; A mesoporous membrane is formed on the substrate and located between the microcolumn arrays. The mesoporous membrane is made of a mesoporous material that absorbs light of a portion of wavelengths in the full spectrum, so that at least a portion of the light passes through the mesoporous membrane.

2. The optoelectronic structure according to claim 1, characterized in that: The substrate is made of transparent conductive material.

3. The optoelectronic structure according to claim 2, characterized in that: The base comprises a transparent substrate and a conductive film arranged on the surface of the substrate.

4. The photovoltaic structure according to claim 1, wherein: The size of the micropillar array is 1 μm-100 μm; and / or The spacing between the micro-pillar arrays is 1 μm-100 μm.

5. The photovoltaic structure according to claim 1, characterized in that: The micro-pillar array is arranged in sequence along a first direction and a second direction perpendicular to each other, and the first direction and the second direction constitute the surface of the substrate.

6. The photovoltaic structure according to claim 1, characterized in that: The micro-pillar array is a prism, a cylinder, a pyramid or a cone.

7. The photovoltaic structure according to claim 1, characterized in that: The photocatalyst is a sulfide photocatalytic material or a metal oxide photocatalytic material.

8. The photovoltaic structure according to claim 1, characterized in that: The thickness of the mesoporous film is smaller than the height of the micropillar array.

9. The photovoltaic structure according to claim 1, characterized in that: The mesoporous material includes TiO2, WO3 or ZnO.

10. A dual-photoelectrode photoelectrochemical cell, characterized in that: include: A battery shell and a photoanode and a photocathode are arranged opposite to each other in the battery shell, and the photoanode comprises the photovoltaic structure according to any one of claims 1-9.

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