Interface water photovoltaic power generation method and application thereof

Abstract

The invention discloses an interface water photovoltaic power generation method, which is characterized in that a conductive substrate with a super-hydrophilic coating on the surface is used as a hydrophilic electrode, the contact interface of the surface of the hydrophilic electrode and water is illuminated, and the interface water formed on the surface of the super-hydrophilic coating is used as a proton semiconductor material to realize photovoltaic power generation. According to the invention, the interface water generated by a hydrophilic material is used as a proton semiconductor for the first time to realize energy conversion among light, water and electricity, and the interface water solar cell is assembled. The battery adopts interface water as a medium, so that the battery is green and clean in the electricity generation process, and basically does not generate byproducts harmful to human bodies or the environment in the device preparation and assembly process, and the problem of environmental pollution caused by photovoltaic material production in the existing photovoltaic power generation technology can be effectively solved; therefore, the method has a good application prospect and a high application value.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and in particular relates to an interfacial water photovoltaic power generation method and application thereof. Background Art

[0002] Solar energy is a clean, efficient, carbon-free new energy source, and photovoltaic power generation is currently the most direct and cleanest way to utilize solar energy. Existing photovoltaic power generation technology is based on the photovoltaic effect of semiconductors to convert solar energy into electrical energy, and the device that converts solar energy into electrical energy is a solar cell. Based on the semiconductor materials used in solar cells, solar cells can currently be divided into the following three categories: (1) Silicon-based solar cells. This type of cell uses single-element silicon as the light-absorbing material. According to the different crystallization characteristics of silicon-based materials, it can be divided into single-crystal silicon solar cells, polycrystalline silicon solar cells and amorphous silicon solar cells. As the first generation of solar cells, single-crystal silicon solar cells were the first to be developed and are currently the most mature solar cells. This type of solar cell has high production efficiency, mature preparation process and stable structure. It has been widely used in photovoltaic power stations of different sizes. Despite this, the purity of single-crystal silicon required for the preparation of solar cells is as high as 99.999%. It is extremely difficult to purify, the preparation process is complex, the cost is high, and there are serious environmental pollution problems such as high energy consumption, high pollution and high carbon emissions. Therefore, it seriously restricts the large-scale promotion and application of single-crystal silicon solar cells.

[0003] (2) Compound thin-film solar cells, also known as the second generation of solar cells. This type of cell often uses binary compounds (such as gallium arsenide GaAs, cadmium sulfide CdS and cadmium telluride CdTe) or more complex ternary compounds (such as copper indium gallium selenide CIGS) as semiconductor light-absorbing materials. Compared with silicon-based solar cells, thin-film solar cells have the characteristics of simple preparation process and low raw material consumption. At present, both CdTe and CIGS solar cells have been successfully industrialized. However, CdTe cells contain the highly toxic element Cd, which poses a great threat to the natural environment and human health, while Te, In and Se are rare elements with very limited reserves. Therefore, thin-film solar cells are still not the most ideal substitute for silicon-based solar cells.

[0004] (3) New solar cells. This type of cell mainly includes organic-polymer solar cells, dye-sensitized solar cells, quantum dot solar cells and perovskite solar cells. The main difference from the first two types of photovoltaic devices is that this type of cell uses a large amount of organic compound materials and nanomaterials in its structure. Therefore, the cell has a higher theoretical efficiency, lower material cost and simpler preparation process. However, the light absorption range of organic solar cells is narrow and does not match the solar spectrum, which leads to insufficient light utilization and low carrier mobility. The liquid electrolyte contained in dye-sensitized solar cells will undergo some irreversible reactions other than redox cycle reactions. Therefore, the device stability is poor. In addition, the commonly used dyes in this cell contain precious metal ruthenium, which is expensive and is not conducive to the promotion and use of the device. Although perovskite solar cells have achieved high photoelectric conversion efficiency, the problems of battery stability and lead pollution remain to be solved.

[0005] It can be seen that although the photoelectric conversion process of solar cells is green and clean, the preparation of semiconductor materials and the production of batteries will have adverse effects on human health and the ecological environment to varying degrees. Therefore, the existing photovoltaic power generation technology is still not a truly green and clean technology.

[0006] It is well known that electronic semiconductor materials will produce electron / hole separation after light exposure, and water can spontaneously dissociate into hydrogen ions and hydroxide ions. Since the diffusion rate of hydrogen ions and hydroxide ions is similar to that of electrons, the self-dissociation process of water molecules can be regarded as the electron / hole separation process of electronic semiconductor materials. Therefore, some studies have proposed that water is a protonic semiconductor material similar to electronic semiconductor materials, with an energy gap of about 1.04 eV. However, due to the low light absorption rate and high resistivity of bulk water, and the fact that the self-dissociated hydrogen ions and hydroxide ions can easily recombine into water, there is currently no report on assembling solar cells using water as a protonic semiconductor.

[0007] Research in the past two decades has found that interfacial water on hydrophilic surfaces has special photoelectric properties different from bulk water, such as enhanced conductivity, characteristic ultraviolet absorption at 270 nm, and a significant increase in the thickness of the interfacial water film after illumination. Based on these photoelectric properties of interfacial water, the present invention uses interfacial water produced by hydrophilic materials as a proton semiconductor for the first time to achieve energy conversion between light, water, and electricity, and assembles interfacial water solar cells. By regulating the surface hydrophilicity and hydrophobicity of the electrode material, the thickness of the interfacial water can be increased, the light-water-electricity conversion efficiency of the interfacial water can be improved, and the output power of the interfacial water solar cell can be increased. Summary of the invention

[0008] The purpose of the present invention is to provide a method for interfacial water photovoltaic power generation, which uses interfacial water generated by hydrophilic materials as a proton semiconductor to achieve energy conversion between light-water-electricity.

[0009] To achieve the above object, the present invention adopts the following technical solution: A method for interfacial water photovoltaic power generation, which uses a conductive substrate with a super-hydrophilic coating on its surface as a hydrophilic electrode, illuminates the contact interface between the hydrophilic electrode surface and water, and utilizes interfacial water formed on the surface of the super-hydrophilic coating as a proton semiconductor material to achieve photovoltaic power generation.

[0010] Furthermore, the contact angle of the superhydrophilic coating is less than 10°.

[0011] Furthermore, the super hydrophilic material used can be nano-TiO2 or graphene hydrogel.

[0012] Furthermore, the conductive substrate includes any one of metal, conductive glass, and conductive film.

[0013] The above method can be used to prepare an interfacial water solar cell, which is constructed by using a hydrophilic electrode prepared on a conductive substrate with a super-hydrophilic coating on the surface as a photoanode, the same conductive substrate as a photocathode, and water as a medium. When in use, the side of the photoanode with the super-hydrophilic coating faces the photocathode and is placed in water parallel to the photocathode. After connecting with a wire, a light source is vertically irradiated on the interface between the photoanode and water, so that interfacial water is formed on the surface of the super-hydrophilic coating, and the formed interfacial water is used as a proton semiconductor material to realize light-water-electricity conversion.

[0014] The significant advantages of the present invention are: Different from the existing electronic semiconductor photovoltaic power generation theory, the present invention uses interfacial water with special photoelectric properties as a proton semiconductor to perform energy conversion between light, water and electricity, and improves the surface hydrophilicity of the electrode material to improve the working efficiency of the interfacial water, thereby improving the performance of the interfacial water solar cell. Among them, because the interfacial water is a carrier and working medium of renewable clean energy, the interfacial water solar cell constructed using it is not only green and clean in the power generation process, but also basically does not produce by-products that are harmful to the human body or the environment during the device preparation and assembly process. The impact on human society and the ecological environment is extremely low, and it can effectively solve the environmental pollution problem caused by the production of photovoltaic materials in the existing photovoltaic power generation technology. In other words, the whole process is green, clean and low-carbon, which is the biggest difference and advantage between the interfacial water solar cell technology and the existing photovoltaic power generation technology.

[0015] At the same time, interfacial water solar cells are based on light and water, the two cleanest, most abundant and renewable resources on earth. They can be used on a small scale or developed on a large scale. Especially in large-scale development and utilization, since 70% of the earth's surface is covered by vast oceans or water bodies such as rivers, lakes, etc., solar power plants based on interfacial water photovoltaic power generation technology can be deployed on large natural water bodies such as oceans and lakes, without occupying precious and scarce land resources like existing large photovoltaic power stations. Therefore, interfacial water solar cell technology has a scale effect that cannot be matched by existing photovoltaic power generation technology.

[0016] In conclusion, the interfacial water solar cell technology proposed in the present invention is a truly green and clean technical solution for utilizing solar energy. The method is safe and reliable, green and environmentally friendly, simple and easy to implement, highly stable, has no pollution emissions, consumes no fuel, is not restricted by resource distribution, and can generate electricity on-site where there is water, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a working principle diagram of the interfacial water solar cell constructed in the present invention.

[0018] Figure 2 Surface scanning electron microscope image (A) and water contact angle (B) of the FTO conductive glass used in Example 1.

[0019] Figure 3 This is a schematic diagram of the structure of the interfacial water solar cell constructed in Example 2, wherein 1 is conductive glass, 2 is a nano-TiO2 hydrophilic layer, and 3 is an interfacial water layer.

[0020] Figure 4 The surface scanning electron microscope image (A) and water contact angle (B) of the nano-TiO2 hydrophilic electrode of Example 2.

[0021] Figure 5 This is a performance diagram of the interfacial water solar cell constructed with nano-TiO2 as the hydrophilic material in Example 2, where a is the performance of a single cell, b is the performance of 4 cells connected in series, c is the voltage after different numbers of cells are connected in series, d is the current after different numbers of cells are connected in parallel, e is the timer driven by the solar cell, and f is the red LED lamp bead lit by the solar cell.

[0022] Figure 6 This is a performance diagram of the interfacial water solar cell constructed using graphene hydrogel as the hydrophilic material in Example 3. DETAILED DESCRIPTION

[0023] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0024] Embodiment 1: (1) Two identical pieces of FTO conductive glass (size 1 cm × 3 cm) were ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 20 minutes. The water contact angle of the surface was about 48.3° (e.g. Figure 2 ).

[0025] (2) The two washed FTO sheets are placed parallel to each other in deionized water to prepare an interfacial water solar cell, in which the interfacial water produced by the photoanode is the proton semiconductor material of the cell.

[0026] The light source was vertically irradiated at the interface between one of the FTO conductive glass sheets (i.e., the photoanode) and water under standard sunlight conditions (1000 W / m 2 ), the open circuit voltage and short circuit current of the battery are only 10 mV and 3 nA, and the photoelectric conversion efficiency is less than 1‰.

[0027] Embodiment 2: (1) Two identical pieces of FTO conductive glass (size 1 cm × 3 cm) were ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 20 min respectively.

[0028] (2) Titanium acetylacetonate was dissolved in n-butanol to prepare a 0.25 mol / L titanium dioxide precursor solution. Then, 100 μL of the obtained titanium dioxide precursor solution was evenly coated on one of the cleaned FTO conductive glass sheets by spin coating (rotation speed was 1500 rpm). The solution was then calcined at 450°C for 1 hour to obtain a hydrophilic electrode containing anatase nano-titanium dioxide particles on the surface. The surface water contact angle was 6.4°.

[0029] (3) The obtained hydrophilic electrode containing rutile nano-titanium dioxide particles on the surface was used as a photoanode, another piece of FTO conductive glass was used as a photocathode, and an aqueous solution with a pH value of 10 was used as a medium to construct an interfacial water solar cell. The interfacial water formed between the TiO2 surface and water under light was used as a proton semiconductor material (i.e., light-water-electricity energy conversion material) for photovoltaic power generation.

[0030] The light source was vertically irradiated at the interface between the hydrophilic electrode (i.e., the photoanode) and water. After testing, under a standard sunlight condition (1000 W / m 2), the open circuit voltage and short circuit current of the battery are stable at 0.35 V and 15 μA respectively, and the photoelectric conversion efficiency is about 8.75%. This is because TiO2 is more hydrophilic than FTO, so the long-range interface interaction between the hydrophilic material and water is enhanced, and the thickness of the interfacial water layer also increases (through a microscope, it can be observed that there is an interfacial water film with a thickness of about 80 μm on the surface of TiO2), thereby improving the light-water-electricity conversion efficiency of the interfacial water. Through multi-module series and parallel connection, the interfacial water battery can successfully light up a red LED bulb and drive an electronic watch to run for up to 1 hour (such as Figure 5 ).

[0031] Embodiment 3: (1) Two identical pieces of FTO conductive glass (size 1 cm × 3 cm) were ultrasonically cleaned in acetone, anhydrous ethanol, and deionized water for 20 min respectively.

[0032] (2) The graphene oxide (GO) solution was synthesized by the modified Hummers method. The GO solution (30 mL) with a concentration of 3 mg / mL was then vigorously stirred for 1 h in an ice-water bath to uniformly disperse the GO. After degassing for 10 min, the GO solution was added to a hydrothermal reactor and reacted at 180 °C for 12 h to obtain a superhydrophilic graphene hydrogel.

[0033] (3) The prepared super-hydrophilic graphene hydrogel was evenly coated on a piece of cleaned FTO conductive glass with a thickness of about 1 mm, thereby obtaining a hydrophilic electrode with a super-hydrophilic graphene hydrogel coating, and its surface water contact angle was about 4.6°.

[0034] (4) An interfacial water solar cell was constructed using the obtained hydrophilic electrode with super-hydrophilic graphene hydrogel coating as a photoanode, another piece of FTO conductive glass as a photocathode, and an aqueous solution with a pH value of 10 as a medium. The interfacial water formed between the surface of the graphene hydrogel coating and water under light was used as a proton semiconductor material (i.e., light-water-electricity conversion material) for photovoltaic power generation.

[0035] The light source was vertically irradiated at the interface between the hydrophilic electrode (i.e., the photoanode) and water. After testing, under a standard sunlight condition (1000 W / m 2 ), the open circuit voltage of the battery can reach 0.5 V, and the short circuit current is increased to 0.2 mA (such as Figure 6 ), the photoelectric conversion efficiency is about 10.11%. This is because graphene hydrogel has more excellent hydrophilic properties, which can further enhance the surface hydrophilicity of the electrode material, thereby improving the output power of the interfacial water solar cell.

[0036] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for interfacial water photovoltaic power generation, characterized in that: A conductive substrate with a super-hydrophilic coating on its surface is used as a hydrophilic electrode. By irradiating light on the contact interface between the hydrophilic electrode surface and water, interfacial water formed on the surface of the super-hydrophilic coating is used as a proton semiconductor material to achieve photovoltaic power generation.

2. The method for interfacial water photovoltaic power generation according to claim 1, characterized in that: The contact angle of the superhydrophilic coating is less than 10°.

3. The method for interfacial water photovoltaic power generation according to claim 1, characterized in that: The conductive substrate includes any one of metal, conductive glass and conductive film.

4. An interfacial water solar cell prepared by the method of claim 1.

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