A photoelectrocatalytic reaction cell applicable to thin film samples

Abstract

The present invention belongs to the field of photoelectrochemical reactions, and discloses a photoelectrocatalytic reaction cell suitable for thin film samples. The photoelectrocatalytic reaction cell suitable for thin film samples includes: different main cavities separated by a proton membrane and used for adding different electrolytes to carry out photocatalytic reactions simultaneously; Pt is deposited on the inner surface of one end of the main cavity as a counter electrode to reduce the system overpotential; a circulating water system is externally added to the main cavity to ensure a constant electrolyte temperature during the sample test process. The present invention is small in size, effectively shortens the electrode spacing, greatly increases the current during the reaction process, is conducive to the progress of the catalytic reaction, and improves the photocatalytic efficiency. The structure of the present invention is simple, the installation and disassembly methods are simple and flexible, it is easy to clean, and at the same time it is resistant to acids and alkalis and is suitable for testing in various electrolyte systems. Moreover, after assembly, the structure is tight, there will be no liquid leakage phenomenon, and at the same time it can ensure the purity of the electrolyte and avoid contamination from the reaction cell.

Description

Technical Field

[0001] The present invention belongs to the field of photoelectrochemical reactions, and particularly relates to a photoelectrocatalytic reaction cell suitable for thin film samples. Background Art

[0002] At present, artificial photosynthesis mimics the photosynthesis in nature, converting inorganic substances such as carbon dioxide and water into organic substances such as hydrogen peroxide, formic acid, and ethanol through solar energy, thereby realizing the conversion of solar energy into chemical energy. It is one of the potential ways to solve the energy crisis and environmental problems. However, limited by the selective generation of products and the spontaneous degradation of the generated products during the process of artificial photosynthesis, artificial photosynthesis cannot be actually popularized and used at present. Therefore, the focus of artificial photosynthesis lies in the development and design of highly selective semiconductor photoanodes.

[0003] A photoanode is usually composed of a semiconductor thin film grown on a conductive substrate. At present, the testing of photoelectrochemical products of photoanodes is mainly carried out in a photoelectrochemical reaction cell. A conventional H-type photoelectrochemical reaction cell generally consists of two identical cylindrical glass containers, which are fixedly sealed by raw rubber and flanges in the middle. There is a quartz window on one side of the reaction cell, and external condensed water is added. This reaction cell has certain advantages, but its defects are also very obvious.

[0004] Through the above analysis, the problems and defects existing in the commonly used photoelectrochemical reaction cells in the prior art are as follows:

[0005] (1) The reaction cell has a large volume and low yield: The reaction cell has a large volume, requiring a large amount of electrolyte. At the same time, the large volume will make the distance between the two photoanodes relatively far, thus restricting mass transfer and introducing a large overpotential, resulting in a small current generated during the reaction process, which is not conducive to the progress of the catalytic reaction.

[0006] (2) Low test accuracy and poor repeatability: When the sample in the conventional reaction cell undergoes a photoelectrochemical reaction, it is difficult to fix the area of the working electrode, and the position of the electrode cannot be completely fixed during each test, resulting in different light intensities received by the sample in actual tests and poor test repeatability. Directly introducing gas into the electrolyte during the reaction process or directly extracting samples from the electrolyte during the reaction will cause disturbances to the reaction system. In addition, the two chambers of the reaction cell are connected by raw rubber and flanges, and it is very easy to occur liquid leakage, resulting in abnormal testing.

[0007] (3) Prone to loss and increasing research costs: Usually, the previously used H-type photoelectrochemical reaction cell is made of quartz, with a complex structure and is very easy to break. At the same time, the quartz reaction cell has poor stability in strong alkaline electrolytes and cannot work continuously for a long time. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a photoelectrocatalytic reaction cell suitable for thin film samples.

[0009] The present invention is implemented as follows. A photoelectrocatalytic reaction cell suitable for thin film samples includes: a first main cavity and a second main cavity;

[0010] Both the first sample and the second sample are thin films grown on transparent conductive glass. When a photoelectrochemical reaction occurs on one side, the sample on the other side is replaced with a platinum electrode;

[0011] The inner cavity surface of the second main cavity is coated with a Pt film of 20 nm to 50 nm, forming one end of the Pt electrode. When in a single electrode reaction, it serves as the Pt counter electrode, and both ends can be used for illumination in a single electrode reaction system; and the coating on the inner cavity surface increases the area of the counter electrode, shortens the electrode spacing, and reduces the system overpotential;

[0012] When reactions occur simultaneously on both electrodes, a photoelectrode of another sample is placed at one end of the second main cavity. The structure of the reaction cell enables a relatively short distance between the two electrodes, and good photocurrent can be obtained to carry out photoelectrocatalytic reactions.

[0013] The inner cavity surface of the second main cavity is coated with 20 to 50 nm of Pt to form the Pt electrode. When in a single electrode reaction, it serves as one end of the Pt electrode. At this time, quartz glass is placed at the position where the sample is placed in the second main cavity, so that light can pass through both sides, realizing illumination from both ends. The reaction sample is placed at the other end as usual for reaction. If Pt is not coated inside the main cavity, a Pt sheet needs to be placed on one side of the second main cavity during a single electrode reaction. Firstly, it will increase the electrode spacing and affect mass transfer. Secondly, the placed Pt sheet will block light, resulting in the inability to illuminate from both sides.

[0014] When reactions occur simultaneously on both electrodes, a photoelectrode is placed at one end of the second main cavity, and a photoelectrode is still placed in the first main cavity at the same time, forming a two - electrode system. The position where Pt is coated is on the inner cavity surface of the second main cavity and will not contact the placed photoelectrode, thus having no impact on the process of simultaneous reactions of the two electrodes.

[0015] Furthermore, in the assembly of the photoelectrocatalytic reaction cell suitable for thin film samples, three groups of screws are used to fix the components together; the specific installation sequence: one group of large screws connects the first main cavity and the second main cavity, and the other two groups of small screws fix the first sample cover, the first sample, and the first main cavity, as well as the second sample cover, the second sample, and the second main cavity. In the test system, the positions of the samples are fixed with three groups of screws, ensuring repeatability and preventing liquid leakage. At the same time, the structure is simple and convenient for disassembly and cleaning.

[0016] Further, the first main cavity and the second main cavity are separated by a proton membrane. The proton exchange membrane is of the N117 type and is used to separate the photoanode and the cathode, allowing different electrolytes to be added simultaneously for photocatalytic reactions in different main cavities. At the same time, it provides a channel for the migration and transportation of protons.

[0017] Further, cavities are opened in the centers of the first main cavity and the second main cavity. Together with the first sample and the second sample through silicone rubber seals, they form an electrolyte storage pool, which is separated by a proton exchange membrane in the middle.

[0018] The sizes of both the first main cavity and the second main cavity are 5×5×1 cm 3 , and the volumes of the cavities opened in the centers are 2×2×1 cm 3 .

[0019] The photocatalytic reaction cell applicable to thin film samples further includes: 2 identical sample covers, samples, seal rings and fixing screws, and an interface for connecting to an external circulating water system.

[0020] A circulating water system for ensuring a constant electrolyte temperature during the sample test is externally added to the main cavity.

[0021] Both the first main cavity and the second main cavity are provided with plastic hose adapters on the sides to connect to the circulating water system, enabling the electrolyte to circulate from bottom to top. This keeps the electrolyte temperature constant and ensures that the system will not be disturbed during ventilation and sampling.

[0022] Further, a threaded hole is also opened on the upper surface of the first main cavity for the sealing and fixing of a miniature Ag / AgCl reference electrode during unilateral photocatalytic reactions.

[0023] The seal ring is silicone rubber protected by polytetrafluoroethylene.

[0024] Further, the first main cavity and the second main cavity are respectively provided with windows on the outside, and samples are placed on both sides for testing; the first main cavity and the second main cavity are used for testing the photocatalytic reactions of unilateral electrodes, and are also used for placing photo electrodes in the first main cavity and the second main cavity simultaneously for photocatalytic reactions.

[0025] Further, the reaction cell material is acid and alkali resistant and is suitable for various electrolytes.

[0026] Another object of the present invention is to provide a reaction cell for preparing hydrogen peroxide, and the reaction cell for preparing hydrogen peroxide is equipped with the photocatalytic reaction cell applicable to thin film samples.

[0027] Another object of the present invention is to provide a reaction cell for preparing ethanol or formic acid, and the reaction cell for preparing ethanol is equipped with the photocatalytic reaction cell applicable to thin film samples.

[0028] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0029] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving such problems, closely combined with the technical solutions to be protected by the present invention and the results and data during the R & D process, etc., analyze in detail and profoundly how the technical solutions of the present invention solve the technical problems and the creative technical effects brought about after solving the problems. The specific description is as follows:

[0030] The present invention solves the problems of low production, inaccurate testing, poor repeatability, and high cost limitations in the photoelectrochemical process due to the design defects of the existing photoelectrochemical reaction cell, and provides a photoelectrocatalytic reaction cell applicable to thin film samples that is double-sided transparent, has a small and fixed sample spacing, strong repeatability, can adapt to various testing environments, and is easy to disassemble, which helps to promote the progress of photoelectrochemical reactions.

[0031] The present invention provides a photoelectrocatalytic reaction cell applicable to thin film samples, which can be used to effectively separate the semiconductor thin film photoanode and photocathode, so that oxidation reactions and reduction reactions occur in two chambers respectively. A circulating water system can be externally connected to achieve the effect of constant temperature of the electrolyte circulation. Gas can be introduced from outside the chamber to participate in the reaction through the electrolyte circulation, and at the same time, samples can be taken from the electrolyte circulation outside the chamber for testing the product concentration. By shortening the distance between the working electrode and the counter electrode and increasing the area of the working electrode, efficient photoelectrochemical reactions are realized, so as to realize reactions such as reducing oxygen to produce hydrogen peroxide and reducing carbon dioxide to produce organic substances through photoelectrochemical reactions. The present invention not only has a simple structure and low cost, but also can ensure that the photoelectrochemical reactions of the samples occur efficiently on the photoanode and photocathode respectively, improving the research quality.

[0032] Structure - function is as follows:

[0033] Through two independent main chambers and a proton separator in the middle, the semiconductor thin film photoanode and photocathode can be effectively separated, so that oxidation reactions and reduction reactions occur in two chambers respectively; at the same time, different electrolytes can be added to the two chambers to selectively carry out the reaction of generating H2O2; at the same time, it can prevent the generated products from degrading.

[0034] The reaction cell material is selected as PEEK, which is acid and alkali resistant and can be applicable to various electrolyte environments.

[0035] Components are connected by tightening screws. The main cavity is sealed with a sealing rubber ring, which can effectively seal the electrolyte and prevent leakage. At the same time, the structure is simple, and the installation and disassembly are convenient and flexible. The connection of the main cavity is convenient for cleaning, effectively avoiding contamination from the reaction cell itself. Meanwhile, the method of combining screws and sealing rubber rings to fix the sample avoids the complex preparation process of working electrodes using traditional conductive silver paste, epoxy resin, glass tubes, etc., greatly simplifies the testing process, and improves the testing efficiency.

[0036] The specially designed main cavity has a small width, effectively shortening the distance between the working electrode and the counter electrode; and the cavity has a large size to obtain a larger working area. The shorter electrode distance and the larger working area result in a higher photocurrent during the photoelectrochemical reaction, thus obtaining more reaction products.

[0037] The inner cavity surface of the main cavity 2 is plated with Pt, so that when a single electrode reaction occurs, it does not block this side window and both ends can be illuminated. At the same time, the internal cavity coating can increase the counter electrode area and shorten the electrode distance to reduce the system overpotential. Thus, a higher photocurrent is obtained, and the yield is further improved. When reactions occur at both electrodes simultaneously, a photoelectrode can still be placed at one end of the second main cavity. Pt will not come into contact with the sample and will not affect the photoelectrode because Pt is located on the inner surface.

[0038] An external circulating water system can be connected to achieve the effect of constant temperature of the electrolyte circulation. Gas can be introduced from outside the chamber, allowing it to participate in the reaction through the electrolyte circulation. At the same time, samples can be taken from the electrolyte circulation outside the chamber for testing the product concentration. This ensures the stability of the system during the reaction and avoids external interference. Meanwhile, the circulating electrolyte ensures that there are sufficient concentrations of ions participating in the reaction to ensure mass transfer.

[0039] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows:

[0040] A photoelectrocatalytic reaction cell suitable for thin film samples provided by the present invention can achieve the separation of the photoanode and photocathode of the semiconductor thin film during the reaction process. It can be used for the preparation of hydrogen peroxide, ethanol, etc. through photoelectrochemical reactions.

[0041] The present invention effectively separates the products of the photoanode and photocathode through a proton diaphragm, which can prevent the degradation of the generated products, improve the selectivity of the products, and effectively improve the photoelectrochemical reaction efficiency. At the same time, different electrolytes can be added to the separated photoanode chamber and photocathode chamber to enhance the selectivity of the photocatalytic products and improve the reaction efficiency.

[0042] The present invention is small in size, effectively shortens the electrode distance, greatly increases the current during the reaction process, facilitates the progress of the catalytic reaction, and improves the photocatalytic efficiency.

[0043] The present invention further effectively shortens the electrode spacing by plating Pt inside the cavity, thereby improving the energy conversion efficiency of the reaction.

[0044] The structure of the present invention is simple, and the installation and disassembly methods are simple and flexible, facilitating cleaning. Meanwhile, it is resistant to acids and alkalis and is applicable to tests in various electrolyte systems. Moreover, after assembly, the structure is tight, there is no liquid leakage phenomenon, and the purity of the electrolyte can be guaranteed, avoiding contamination from the reaction cell.

[0045] The present invention realizes the complete fixation of the position and area of the sample in the incident light spot. Meanwhile, both gas ventilation and sampling are carried out outside the reaction cell, reducing the external disturbance during the photoelectrochemical reaction process. Greatly reducing the test error caused by human factors, it effectively improves the accuracy and repeatability of sample performance testing.

[0046] The present invention ensures the constant temperature of the electrolyte during the test by adding an external circulating water system. During the test of hydrogen peroxide products, the electrolyte temperature is stabilized at 5°C to prevent the decomposition of the generated hydrogen peroxide. Meanwhile, compared with the prior art, the external circulating water system can also introduce gas from the outside, which is more conducive to the progress of the reaction.

[0047] The present invention fixes the position and area of the test sample through a sealing ring and a sample cover plate, avoiding the traditional complex process of preparing a working electrode using conductive silver paste, epoxy resin, glass tubes, etc., greatly simplifying the test process and improving the test efficiency.

[0048] The present invention mainly focuses on the test of the products of the photocatalytic reaction, testing the concentration of liquid products such as hydrogen peroxide and CO2 reduction products.

[0049] The present invention adopts an integrated design, with a compact structure, beautiful appearance, convenient operation, low manufacturing cost, and is easy to be popularized and used on a large scale.

[0050] Thirdly, as the creative auxiliary evidence of the claims of the present invention, it is also reflected in the following important aspects:

[0051] The expected benefits and commercial value after the transformation of the technical solution of the present invention are as follows: The present invention adopts an integrated design, with a compact structure, beautiful appearance, and convenient operation, and can produce H2O2 in a portable manner. Compared with the traditional anthraquinone method for producing H2O2, which has high energy consumption, large pollution, and is not convenient for transportation, the present invention is small in size and easy to carry, and only requires short-time light irradiation to produce a certain concentration of H2O2 for disinfection and sterilization.

[0052] Specific application directions include field-portable H2O2 production equipment, which can quickly produce H2O2 for disinfection and sterilization. The size of this product after assembly is approximately 5×5×3 cm. 3, it meets the need of being small and portable. It can also be used in scenarios that require disinfection such as hospitals, taking up very little space but being able to quickly generate H2O2.

[0053] The technical solution of the present invention fills the technical gaps in the domestic and international industries: the reactor capable of synthesizing H2O2 is of great significance for the large-scale and practical application of the photoelectrochemical synthesis of H2O2. And the photoelectrochemical reaction cell applicable to actual application scenarios (such as hospitals, the wild, etc.) is of great significance for the technology of photocatalytic production of H2O2 to move towards application.

[0054] Currently, there is no standard reaction cell for photocatalytic production of H2O2. The electrode spacing of the conventional H-type reaction cell is relatively large, resulting in a series of problems such as a large internal resistance and low reaction efficiency. What the present invention focuses on solving is the problem of large electrode spacing. The present invention is small in size, the distance between the two electrodes is very close, so the internal resistance is small, and a higher photocurrent can be obtained, thus generating H2O2 more efficiently. Description of the Drawings

[0055] Figure 1 is a partial schematic diagram of the photoelectrochemical reaction cell applicable to thin film samples provided by an embodiment of the present invention;

[0056] Figure 2 is the overall structural schematic diagram of the photoelectrochemical reaction cell applicable to thin film samples provided by an embodiment of the present invention;

[0057] Figure 3 is the diagram of the change of photocurrent-time response and hydrogen peroxide concentration with time under zero bias of the semiconductor provided by an embodiment of the present invention;

[0058] Figure 4 is the schematic diagram of the photocurrent-time response and the change of hydrogen peroxide concentration with time repeated 3 times when the BiVO4 photoanode reacts under a bias of 0.8V vs. Ag / AgCl provided by an embodiment of the present invention;

[0059] Figure 5 is the I-t curve diagram of the BiVO4 photoanode under a bias of 0.8V vs. Ag / AgCl in an H-type photoelectrochemical reaction cell provided by an embodiment of the present invention.

[0060] In the figure: 1. First sample cover plate; 2. First sample; 3. First sealing rubber ring; 4. First main cavity; 5. Second sealing rubber ring; 6. Proton exchange membrane; 7. Third sealing rubber ring; 8. Second main cavity; 9. Fourth sealing rubber ring; 10. Second sample; 11. Second sample cover plate. Detailed Embodiments

[0061] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] I. Explanation of the embodiments. In order to enable those skilled in the art to fully understand how the present invention is specifically implemented, this part is an explanatory embodiment that expands and explains the technical solutions of the claims.

[0063] The embodiment of the present invention provides a photoelectrocatalytic reaction cell suitable for thin film samples. The inner cavity surface of the second main cavity 8 of the reaction cell is coated with a Pt film of 20 nm to 50 nm, forming one end of the Pt electrode. When performing a single electrode reaction, it can be used as a Pt counter electrode, which can ensure that both ends can be irradiated in a single electrode reaction system. And coating the inner cavity can increase the counter electrode area and shorten the electrode spacing to reduce the system overpotential. Thereby obtaining a higher photocurrent and further improving the yield.

[0064] When reactions occur at both electrodes simultaneously, a photoelectrode can still be placed at one end of the second main cavity 8. Pt will not come into contact with the sample and will not affect the photoelectrode because Pt is located on the inner surface.

[0065] In the PEC process, reducing the solution resistance will make the application of the photoelectrode catalytic reaction more extensive. Minimizing the distance between the electrodes can effectively reduce the solution resistance value. A large number of experiments have proven that a shorter electrode spacing can improve the overall energy conversion efficiency. At the same time, reducing the thickness of the electrolyte (i.e., shortening the electrode spacing) will increase the photo-oxidation reduction effect of certain specific redox pairs (such as anthraquinone). In addition, too large an electrode spacing (i.e., channel size) may lead to significant mass transfer phenomena, which will result in a low energy conversion efficiency even with a certain electrolyte flow rate.

[0066] In short, the electrolyte must have a sufficiently low resistance (<2.5 Ω·cm 2 ) to meet the actual application of the optoelectronic material. Experiments have shown that reducing the electrode spacing by 1 cm is equivalent to reducing the solution resistance by about 50%. Therefore, this patent effectively shortens the electrode spacing, can obtain a higher energy conversion efficiency, and thus has a wider application than the previous reaction cell.

[0067] The embodiment of the present invention provides a photoelectrocatalytic reaction cell suitable for thin film samples, which specifically includes:

[0068] Using a proton membrane to separate different main cavities for adding different electrolytes to simultaneously perform photocatalytic reactions;

[0069] A circulating water system is externally added to the main cavity to ensure a constant electrolyte temperature during the sample test.

[0070] With two independent main cavities and a proton separator in the middle, the semiconductor thin-film photoanode and photocathode can be effectively separated, enabling the oxidation reaction and reduction reaction to occur in two chambers respectively; at the same time, different electrolytes can be added to the two chambers to selectively generate H2O2; and the degradation of the generated products can be prevented.

[0071] The reaction cell is made of PEEK, which is acid and alkali resistant and can be applied to various electrolyte environments.

[0072] The components are connected by tightening screws. The main cavity is sealed with a sealing rubber ring, which can effectively seal the electrolyte and prevent leakage. At the same time, the structure is simple, and the installation and disassembly are convenient and flexible. The connection of the main cavity is convenient for cleaning, effectively avoiding contamination from the reaction cell itself. At the same time, the method of combining screws and sealing rubber rings to fix the sample avoids the complex process of preparing working electrodes using traditional conductive silver paste, epoxy resin, glass tubes, etc., greatly simplifies the test process, and improves the test efficiency. Different from the conventional reaction cell fixed by a long screw, through multiple experiments, it is verified that this sample cell uses three groups of screws to jointly play a fixing role, ensuring that each component is tightly combined and in the correct position during the installation process, which can be adjusted once, with a lower probability of error. It can prevent situations such as leakage. The specific installation sequence: one group of large screws connects the first main cavity 4 and the second main cavity, and the other two groups of small screws fix the first sample cover 1, the first sample 2 and the first main cavity 4, and the second sample cover 11, the second sample 10 and the second main cavity 8.

[0073] The specially designed main cavity has a smaller width, effectively shortening the distance between the working electrode and the counter electrode; and the cavity has a larger size, obtaining a larger working area. The shorter electrode distance and the larger working area result in a higher photocurrent during the photoelectrochemical reaction, thus obtaining more reaction products.

[0074] A circulating water system can be externally connected to achieve the effect of constant temperature of the electrolyte circulation. Gas can be introduced from outside the chamber to participate in the reaction through the electrolyte circulation. At the same time, samples can be taken from the electrolyte circulation outside the chamber for testing the product concentration. To ensure the stability of the system during the reaction and avoid external interference. The photoelectrocatalytic reaction cell provided by the embodiment of the present invention performs electrolyte circulation through a circulating water system, and realizes operations such as constant temperature, sampling, and gas introduction of the electrolyte through the electrolyte circulation. At the same time, the circulating electrolyte ensures that there are enough ions with sufficient concentration to participate in the reaction, ensuring mass transfer.

[0075] The embodiment of the present invention also provides a sample detection step for a photoelectrocatalytic reaction cell applicable to thin-film samples (both-sided samples simultaneously undergo photoelectrochemical reactions to generate H2O2):

[0076] 1. Assemble in the order of connecting the first main cavity 4 and the second main cavity with a set of large screws, and fixing the first sample cover plate 1, the first sample 2, and the first main cavity 4 and the second sample cover plate 11, the second sample 10, and the second main cavity 8 with another two sets of small screws. The sample side faces inward. The components of the formed reaction cell are in the order of the first sample cover plate 1, the first sample 2, the first sealing rubber ring 3, the first main cavity 4, the second sealing rubber ring 5, the proton exchange membrane 6, the third sealing rubber ring 7, the second main cavity 8, the fourth sealing rubber ring 9, the second sample 10, and the second sample cover plate 11.

[0077] 2. Both the first main cavity and the second main cavity are connected to the circulating water system through side interfaces and electrolyte is injected respectively.

[0078] 3. Turn on the water cooling system to keep the electrolyte temperature constant at 5°C. At the same time, ventilate in the externally connected circulating water system: Ar gas is introduced on the photoanode side and O2 is introduced on the photocathode side for 30 minutes of gas washing.

[0079] 4. Connect the photoanode and photocathode (it can be connected to the two-electrode system of the electrochemical workstation and monitored the current during the reaction under a constant 0V).

[0080] 5. Turn on the light source to irradiate the sample to start the reaction.

[0081] 6. Take the electrolyte at the same interval and test the H2O2 content in the electrolyte.

[0082] Example 1

[0083] As shown in Figure 1 - Figure 2 As shown, the embodiment of the present invention provides a photoelectrocatalytic reaction cell suitable for thin film samples. The main body of the reaction cell is composed of PEEK, mainly including 2 mirror-image main cavities - the first main cavity ( Figure 1b ) and the second main cavity ( Figure 1c ), 2 identical sample cover plates ( Figure 1a ), a proton exchange membrane, a sealing rubber ring and fixed screws, and an interface for externally connecting the circulating water system.

[0084] During use, the reaction cell will be connected and fixed in the order of the first sample cover plate 1, the first sample 2, the first sealing rubber ring 3, the first main cavity 4, the second sealing rubber ring 5, the proton exchange membrane 6, the third sealing rubber ring 7, the second main cavity 8, the fourth sealing rubber ring 9, the second sample 10, and the second sample cover plate 11 with stainless steel screws. Both the first main cavity and the second main cavity are connected to the circulating water system through side interfaces. The sample is a thin film grown on a transparent conductive glass. When a photoelectrochemical reaction occurs on one side, the sample on the other side is replaced with a quartz sheet.

[0085] In the embodiment of the invention, the proton exchange membrane is of the N117 type, which can be used to separate the photoanode and the cathode and at the same time provide a channel for the migration and transportation of protons.

[0086] In the invention embodiment, the sizes of the two main cavities are both 5×5×1 cm 3 , and the center thereof is a cavity with a volume of 2×2×1 cm 3 . Through a silica gel sealing ring, it forms an electrolyte storage pool with two samples of 3.3×3.3 cm 2 . The middle is separated by a proton exchange membrane; meanwhile, a plastic hose adapter with a diameter of 1 mm is provided on the side of each of the two main cavities for the circulation of the electrolyte (entering from the bottom and exiting from the top); in addition, there is a threaded hole with a size of 6.2 mm on the upper surface of the first main cavity for the sealing and fixation of the micro Ag / AgCl reference electrode during the occurrence of unilateral photoelectrocatalytic reaction. When the two electrodes react simultaneously, this hole is sealed with a screw.

[0087] In the invention embodiment, a Pt film with a thickness of 20 - 50 nm is plated on the inner cavity surface of the main cavity 2, which serves as a counter electrode during the occurrence of unilateral photoelectrocatalytic reaction.

[0088] In the invention embodiment, polytetrafluoro - protected silica gel is used as the sealing ring, which can prevent the corrosion of most electrolytes such as acidic and alkaline electrolytes.

[0089] In the invention embodiment, the first main cavity and the second main cavity are respectively provided with windows on the outside, and samples can be placed on both sides for testing simultaneously. That is, not only can the photocatalytic reaction of a single - side electrode be tested, but also photo - electrodes can be placed on both sides for simultaneous photocatalytic reaction.

[0090] Shortening the distance between the two electrodes to 2 cm can effectively increase the photocurrent in the photoelectrochemical process, thereby improving the efficiency of the photoelectrochemical reaction. At the same time, the positions of the two electrodes are fixed, which improves the repeatability and comparability of the test.

[0091] In the invention embodiment, an external circulating condensed water system can be connected for the temperature constancy of the electrolyte. When reaction gases are introduced from the outside and reaction samples are taken out, it will not cause disturbance to the main photoelectrochemical process.

[0092] Example 2

[0093] The photoelectrocatalytic reaction cell applicable to thin - film samples provided by the invention embodiment, during the test process, the photoanode and the photocathode are separated by a proton diaphragm. At the same time, the distance between the photoanode and the photocathode is relatively close, which can achieve the effects of separating products and improving the photoelectrocatalytic efficiency, and at the same time improve the repeatability of the test. The two - chamber reaction cell can place electrodes at both ends simultaneously for reaction. At the same time, different electrolytes can be added to the two chambers separated by the proton diaphragm to improve the selectivity for the photocatalytic reaction products.

[0094] II. Application Examples. To prove the creativity and technical value of the technical solution of the present invention, this part provides application examples of the technical solution of the claims on specific products or related technologies.

[0095] Application Example 1 - Simultaneous Photoelectrochemical Generation of H2O2 at Photoanode and Photocathode

[0096] An n-type semiconductor - bismuth vanadate thin film photoanode and a p-type semiconductor - cupric bismuthate photocathode are prepared on FTO conductive glass by spin coating. Hydrogen peroxide is generated simultaneously at the photoanode and photocathode, and the specific implementation steps and details of the photoelectrocatalytic reaction cell applicable to thin film samples proposed by the present invention are described in detail.

[0097] Preparation of Photoanode: The photoanode used this time is a bismuth vanadate thin film prepared on FTO conductive glass by spin coating. A 0.2M and 0.03M solution of bismuth nitrate (5 mL) and vanadyl acetylacetonate (33 mL) is prepared with acetylacetone as the solvent. After ultrasonic treatment for 10 min respectively, they are mixed evenly and ultrasonic treatment is continued for 10 min to obtain the precursor solution of bismuth vanadate. Then spin coating is carried out at a speed of 1000 r / min for 20 s. After repeating spin coating 8 times, the obtained thin film is calcined in air at 480 °C for 2 h to obtain the photoanode sample. The obtained sample is cut into 3.3×3.3 cm 2 , and a corner is erased with dilute hydrochloric acid to expose part of the FTO, and a conductive copper tape is connected to make the photoanode for testing.

[0098] Preparation of Photocathode: The photocathode used this time is a cupric bismuthate thin film prepared by spin coating on FTO conductive glass. Cupric nitrate and bismuth nitrate with a molar ratio of 1:2 are dissolved in ethylene glycol monomethyl ether to form the precursor solution of cupric bismuthate. Then spin coating is carried out at a speed of 2000 r / min for 30 s. After repeating spin coating 8 times, the obtained thin film is calcined in air at 500 °C for 1 h to obtain the photocathode sample. The obtained sample is cut into 3.3×3.3 cm 2 size, and a corner is erased with dilute hydrochloric acid to expose part of the FTO, and a conductive copper tape is connected to make the photocathode for testing.

[0099] Preparation of Electrolyte: The anodic electrolyte is a 0.5M potassium bicarbonate solution with an electrolyte pH of 7.9; the cathodic electrolyte is a pH buffer - mixed phosphate solution with an electrolyte pH of 6.86.

[0100] Reaction cell assembly: First, fix four sealing rings in the corresponding grooves of the main cavity. Then, connect the first main cavity 4 and the second main cavity with a set of large screws, and tighten the fixing screws in sequence according to the order of the other two sets of small screws to fix the first sample cover plate 1, the photoanode (with the conductive side facing in), and the first main cavity 4, and the second sample cover plate 11, the photocathode (with the conductive side facing in), and the second main cavity 8; screw the screws into the reserved threaded holes above the main cavity on the photoanode side to achieve sealing; then align the reaction cell, add the electrolyte, and tighten the sealing interface to complete the assembly.

[0101] Testing:

[0102] Thirty minutes in advance, introduce oxygen into the photocathode end and argon into the photoanode end, and continue to introduce them during the reaction process.

[0103] Place the photoanode and the photocathode under AM 1.5G simulated sunlight illumination respectively. Under the condition of no external bias voltage, test the I-t curve of the sample through a two-electrode system to obtain the data as Figure 3 shown.

[0104] Application Example 2 - Photoelectrochemical generation of H2O2 at the photoanode end

[0105] Prepare an n-type semiconductor - bismuth vanadate thin film photoanode on FTO conductive glass by spin coating method to generate hydrogen peroxide, and elaborate on the specific implementation steps and details of the photoelectrocatalytic reaction cell applicable to thin film samples proposed in the present invention.

[0106] Photoanode preparation: The photoanode used this time is a bismuth vanadate thin film prepared on FTO conductive glass by spin coating process. Prepare 0.2M and 0.03M bismuth nitrate (5 mL) and vanadyl acetylacetonate (33 mL) solutions with acetylacetone as the solvent, ultrasonicate for 10 min respectively, then mix them evenly and continue to ultrasonicate for 10 min to obtain the precursor solution of bismuth vanadate. Then spin coat at a speed of 1000 r / min for 20 s. After repeating the spin coating 8 times, calcine the obtained thin film in air at 480 °C for 2 h to obtain the photoanode sample. Cut the obtained sample into 3.3×3.3 cm 2 , and erase one corner with dilute hydrochloric acid to expose part of the FTO, and connect the conductive copper tape to make the photoanode for testing.

[0107] Electrolyte preparation: The electrolyte is 0.5M potassium bicarbonate solution, and the pH of the electrolyte is 7.9.

[0108] Reactor Assembly: First, fix four sealing rings in the corresponding grooves of the main cavity. Then, connect the first main cavity 4 and the second main cavity with a set of large screws, and sequentially tighten the fixing screws in the order of fixing the first sample cover plate 1, the photoanode (with the conductive side facing inwards), and the first main cavity 4, the second sample cover plate 11, the quartz glass, and the second main cavity 8 with the other two sets of small screws; insert the micro Ag / AgCl reference electrode into the threaded hole reserved above the main cavity on the photoanode side; then align the reactor, add the electrolyte, and tighten the sealing interface to complete the assembly.

[0109] Testing:

[0110] Introduce argon into both ends 30 minutes in advance and continuously introduce it during the reaction process.

[0111] Place the photoanode under AM 1.5G simulated sunlight illumination, apply a bias voltage of 0.8V vs. Ag / AgCl to the photoanode through a three-electrode system, perform an I-t scan to generate H2O2. As Figure 4 shown.

[0112] Similarly for the photocathode, replace the photoanode end with the photocathode and apply a negative bias voltage.

[0113] Application Example 3 - Photocatalytic CO2 Reduction

[0114] Photocatalytic CO2 reduction utilizes a p-type semiconductor photocathode, and the other side is a Pt electrode. CO2 is introduced during the reaction process and samples are taken at intervals. This reactor mainly tests and collects liquid products.

[0115] III. Evidence of Related Effects of the Embodiment. Some positive effects have been achieved during the research and development or use of the embodiments of the present invention, and there are indeed great advantages compared with the prior art. The following content is described in combination with the data, charts, etc. of the test process.

[0116] Figure 3 It is a graph showing the change of photocurrent-time response and hydrogen peroxide concentration with time under zero bias of the semiconductor provided by the embodiment of the present invention. a) The curve of the change of photocurrent with time during the simultaneous reaction of the photoanode and photocathode under 0 bias. b) The graph of the change of the yield of H2O2 generated by the simultaneous reaction of the photoanode and photocathode with time, with the photoanode being n-BiVO4 and the photocathode being p-CuBi2O4.

[0117] Figure 4 It is a graph showing the change of the hydrogen peroxide concentration generated by the photoelectrocatalysis of the semiconductor photoanode of the embodiment of the present invention with time. It is only the process of generating H2O2 by the photoanode reaction. a) The curve of the change of photocurrent with time under a bias voltage of 0.8V vs. Ag / AgCl. b) The graph of the change of the yield of H2O2 by the photoanode reaction with time, with each 40 minutes as a cycle and repeated three times to prove repeatability.

[0118] Previously, due to the relatively large electrode spacing in the H-type photoelectrochemical reaction cell, the photocurrent measured for the BiVO4 photoanode of the same material was extremely small. As Figure 5 shown, and no H2O2 generation was detected even after 4 hours of reaction. The main reasons for the analysis are as follows: 1. The relatively large electrode spacing leads to a relatively large internal resistance, which limits the reaction photocurrent. 2. The H-type reaction cell has a relatively large volume, and more electrolyte enters. For the relatively small-area photoanode, H2O2 may be generated, but the concentration is too low to exceed the detection limit, so the generation of H2O2 cannot be detected, and thus it cannot be put into application.

[0119] As mentioned above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A photoelectrocatalytic reaction cell applicable to thin film samples, characterized in that, The photocatalytic reaction cell applicable to thin film samples includes: a first main cavity and a second main cavity; The inner cavity surface of the second main cavity is coated with a Pt film of 20 nm to 50 nm, forming one end of the Pt electrode. When performing a single electrode reaction, it serves as the Pt counter electrode and can be used for light illumination at both ends in a single electrode reaction system; When reactions occur at both electrodes simultaneously, a photo - electrode is placed at one end of the second main cavity, and the Pt electrode is located on the inner surface without contacting the sample, thus not affecting the reaction progress; The inner cavity surface of the second main cavity is coated with 20 - 50 nm of Pt to form the Pt electrode; when performing a single electrode reaction, it serves as one end of the Pt electrode, and a quartz glass is placed at the position where the sample is placed in the second main cavity; When reactions occur at both electrodes simultaneously, a photo - electrode is placed at one end of the second main cavity, and at the same time, a photo - electrode is placed at one end of the first main cavity to form a two - electrode system; The position where Pt is coated is on the inner cavity surface of the second main cavity; In the assembly of the photocatalytic reaction cell applicable to thin film samples, three groups of screws are used to fix the components together; one group of large screws connects the first main cavity and the second main cavity, and the other two groups of small screws fix the first sample cover plate, the first sample, the first main cavity, the second sample cover plate, the second sample, and the second main cavity; The first main cavity and the second main cavity are separated by a proton exchange membrane and are different main cavities for adding different electrolytes to simultaneously carry out photocatalytic reactions; cavities are opened in the centers of the different main cavities; A circulating water system for ensuring a constant electrolyte temperature during the sample test is externally added to the main cavity; The sizes of both the first main cavity and the second main cavity are 5×5×1 cm 3 , and the volume of the cavity opened in the center is 2×2×1 cm 3 .

2. The photoelectrocatalytic reaction cell applicable to thin film samples according to claim 1, characterized in that, The photocatalytic reaction cell applicable to thin film samples further includes: 2 identical sample cover plates, samples, sealing rubber rings, fixing screws, and an interface for externally connecting the circulating water system; Both the first main cavity and the second main cavity are connected to the circulating water system through side interfaces.

3. The photoelectrocatalytic reaction cell applicable to thin film samples according to claim 1, characterized in that, Both the first sample and the second sample are thin films grown on transparent conductive glass. When a photoelectrochemical reaction occurs on one side, a quartz glass is placed at the position of the other sample, and it is connected to the Pt electrode as the counter electrode; The proton exchange membrane is of the N117 type, used to separate the photoanode and the cathode, and at the same time provides a channel for the migration and transport of protons; The first main cavity and the second main cavity have cavities opened in their centers, and together with the first sample and the second sample through silica gel sealing rings, they form an electrolyte storage pool, which is separated by a proton exchange membrane in the middle.

4. The photoelectrocatalytic reaction cell applicable to thin film samples according to claim 1, characterized in that, Plastic hose adapters are provided on the sides of both the first main cavity and the second main cavity for the bottom - in and top - out circulation of the electrolyte.

5. The photoelectrocatalytic reaction cell applicable to thin film samples according to claim 4, characterized in that, Threaded holes are also opened on the upper surface of the first main cavity for the sealing and fixing of the micro Ag / AgCl reference electrode when a single - side photoelectrochemical reaction occurs; The sealing ring is silica gel protected by polytetrafluoroethylene.

6. The photoelectrocatalytic reaction cell applicable to thin film samples according to claim 1, characterized in that, The first main cavity and the second main cavity are respectively provided with windows on the outside, and samples are placed on both sides for testing; the first main cavity and the second main cavity are used for testing the photocatalytic reaction of a single - side electrode and are also used for simultaneously carrying out photocatalytic reactions by placing photo - electrodes in the first main cavity and the second main cavity.

7. A reaction cell for preparing hydrogen peroxide, characterized in that, The reaction cell for preparing hydrogen peroxide carries the photocatalytic reaction cell applicable to thin film samples as described in any one of claims 1 - 6.

8. A reaction cell for preparing formic acid or ethanol, characterized in that, The reaction cell for preparing ethanol or formic acid is equipped with the photoelectrocatalytic reaction cell for thin film samples described in any one of claims 1 to 6.

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