Full water splitting system and method based on BaTaO2N-mediated S-type heterojunction photocatalyst

Abstract

The invention discloses a full water splitting system and method based on a BaTaO2N-mediated S-type heterojunction photocatalyst, and relates to the technical field of photocatalysts.The system comprises a photocatalytic reaction module, a light source module, a gas collection module and a temperature control module; according to the system, a BiVO4 / Ti < 3 > C < 2 > T < x > / BaTaO2N two-dimensional S-type heterojunction photocatalyst is used as a core, wherein Ti < 3 > C < 2 > T < x > is used as a middle layer and is positioned between BiVO4 and BaTaO2N; according to the invention, oxidation reaction of photo-generated holes to water is promoted, proton recombination loss on the surface of the catalyst is reduced in a high-pH environment, the catalyst has more advantages under alkaline conditions, directional migration of photo-generated electrons from BiVO4 to BaTaO2N can be accelerated by taking Ti3C2Tx as a high-conductivity channel, reaction activation energy can be reduced by taking FeNiP and Co (OH) 2 as active sites of hydrogen evolution and oxygen evolution reactions respectively, and the catalytic activity of the catalyst is improved. Compared with a traditional single-component or interlayer-free system, the performance is remarkably improved, and high efficiency, stability and wide pH adaptability are achieved.

Claims

1. A comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst, characterized in that: The system includes a photocatalytic reaction module, a light source module, a gas collection module and a temperature control module; the system is based on BiVO4 / Ti3C2T X / BaTaO2N two-dimensional S-type heterojunction photocatalyst as the core, in which Ti3C2T X As an intermediate layer between BiVO4 and BaTaO2N; The photocatalytic reaction module includes a reaction container for loading BiVO4 / Ti3C2T in the container. X / BaTaO2N photocatalyst and electrolyte solution with pH = 7-14; The light source module is used to drive the photocatalyst to generate photogenerated carriers and stimulate the complete water splitting reaction. It uses a xenon lamp light source with a wavelength of ≥400nm and a light intensity of ≥100mW / cm 2 Visible light with adjustable irradiation angle of 0-90°; The gas collection module is used to separate and collect H2 and O2 generated by the reaction; The temperature control module is used to maintain the reaction temperature at 20-40°C.

2. The comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst according to claim 1, characterized in that: The BiVO4 is an ultra-thin two-dimensional nanosheet structure with a thickness of 50-200 nm and a band gap value of 2.3-2.5 eV; The BaTaO2N is an ultrathin two-dimensional nanosheet with a lateral size of 400-1200 nm and a band gap value of 1.7-1.9 eV; The Ti3C2T X It is a few-layer two-dimensional MXene nanosheet with 2-6 layers, and the surface functional groups include -OH, -O or -F.

3. The comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst according to claim 1, characterized in that: The surface of the photocatalyst is loaded with FeNiP and Co(OH)2 co-catalysts, FeNiP is used to promote hydrogen evolution reaction, and Co(OH)2 is used to promote oxygen evolution reaction.

4. The comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst according to claim 1, characterized in that: The band structure of the S-type heterojunction satisfies: The conduction band potential of BiVO4 is higher than that of BaTaO2N, and the valence band potentials of the two form a gradient difference; The Ti3C2T X It is an electron transmission channel used to realize the directional migration of photogenerated carriers. Photogenerated electrons are transferred from BiVO4 to Ti3C2T X Transferred to BaTaO2N, the photogenerated holes remain on the BiVO4 surface; The photogenerated electron transfer rate is ≥10 7 s -1 , hole lifetime ≥10 -6 s.

5. The comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst according to claim 1, characterized in that: The photocatalyst exists in the reaction container in a suspended state or in the form of being supported on a conductive substrate. The electrolyte solution is an aqueous solution. The irradiation direction of the light source module is perpendicular to the reaction liquid surface.

6. The comprehensive water splitting system based on BaTaO2N-mediated S-type heterojunction photocatalyst according to claim 1, characterized in that: The gas collection module includes independent H2 and O2 collection channels, and a gas separation membrane is provided between the channels. The H2 and O2 collection channels are respectively connected to a gas chromatograph for real-time monitoring of the volume ratio of gas products.

7. A method for completely splitting water using the BaTaO2N-mediated S-type heterojunction photocatalyst according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Synthesis of 2D layered Ti3C2T by etching X -MXene nanosheets, ultrathin 2DBaTaO2N nanosheets were prepared by flux method, and BiVO4, Ti3C2T X Composite with BaTaO2N to form BiVO4 / Ti3C2T X / BaTaO2N heterojunction, and finally loaded with FeNiP and Co(OH)2 co-catalysts; Step 2: Disperse or load the photocatalyst in the reaction vessel, add the electrolyte solution, connect the H2 and O2 collection channels, and align the light source module with the reaction area; Step 3: Turn on the light source module. Under visible light irradiation, the photocatalyst drives the decomposition of water into H2 and O2. The products are collected through the H2 and O2 collection channels respectively. During the reaction, the temperature is controlled at 20-40°C and the pH is maintained at 7-14 by the buffer solution.

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