Design, Synthesis And Photocatalytic Properties Research Of Graphene-based Polyacid Composites

Photocatalysis as an advanced technology, can transform some chemical reactions that occur under harsh conditions into other chemical reactions that can be conducted under mild condition through photocatalysts absorbing certain photo energy under light illumination. The technology plays a unique role in solving the problem of environment pollution, because of its easy operation, green non-pollution, extensive applicability, and so on. Photocatalysis technology not only sets up a new land for environment governance, but also makes a great difference in settling energy crisis. However, as a kind of new technology, it still has some shortcomings. In order to solve the problems of the poor adsorptive performance and the easy recombination of phtoinduced carriers in semiconductor photocatalysts, graphene, with large specific surface area and good conductivity, was introduced in this paper to prepare graphene-based photocatalytic composites with expectation of improved photocatalytic perform of semiconductor photocatalysts. The researches were carried out from the following several aspects:?1? For the problem of high recombination of photoinduced electron-hole pairs in SrWO₄, graphene nanosheets was selected as electrons collectors in this paper to prepare graphene/SrWO₄ nanocomposites through simple chemical precipitation method with the expectation of enhanced photocatlytic activity. As shown in TEM images, SrWO₄ nanoparticles in synthesized graphene/SrWO₄ nanocomposites in this paper deposite dispersedly on the surface of graphene nanosheets. Photocatalytic experiments showed that graphene/SrWO₄ exhibited obviously improved photocatalytic performance compared with pure SrWO₄ and when the content of initial graphite oxide was 4%, the apparent rate constant of graphene/SrWO₄ composites in photocatalytic degradation methyl orange solution was three times bigger than that of pure Sr WO₄.?2? For the high solubility in water and hard to recycle of H3PW12O₄0, K+ with larger ion radius was chosed to precipitate H3PW12O₄0 for forming undissolved solid K₃PW₁₂O₄₀ through chemical precipitation at room temperature. For the problem of poor adsorptive performance and the high recombination rate of electron-hole pairs, Graphene nanosheets was used as support for K₃PW₁₂O₄₀ to synthesize graphene/K₃PW₁₂O₄₀ nanocomposites with water as solvent through a green photoreduction strategy. The introduction of graphene, not only can immobilize catalyst, but can restrain the recombination of electron-hole pairs by transferring electron coming from photoinduced K₃PW₁₂O₄₀. Photocatalytic experiments indicated that: the addition of graphene effecitively improved the photocatalytic performance of materials.?3? K⁺ with large ion radius was adpoted for precipitating H3PMo12O₄0 to shape undissolved solid K3PMo12O₄0. In order to further solve the problem of poor adsorptive performance and the high recombination rate of carriers in K3PMo12O₄0, this paper brought in new nanomaterial graphene. Under the condition of ethanol as solvent and adding surfactant, Graphene/K3PMo12O₄0 composites were prepared in this paper by photoreduction method. As displayed in SEM images, K3PMo12O₄0 wrapped by graphene nanosheets presents flower structure, composed of nanosheeets of about 20 nm thickness in composites. Photocatalytic experiments exhibited that Rhodamine B solution showed obviously improved decolourization rate and larger apparent rate constant value in the case of composites as photocatalysts in contrast with pure K3PMo12O₄0 as photocatalysts.