Preparation Of ZnO-based Nanocomposite Materials And Study For Photoelectrochemical Performance

Recent years, exploiting clean and sustainable energy as well as new techniques for solving increasingly serious environment pollution and energy crisis have been widely focused. As a traditional semiconductor photocatalyst, ZnO has been extensively investigated due to its potential application in environment and energy field. However, the practical application in photocatalysis is extremly restricted due to the wide band gap? 3.2 eV? and fast recombination of photoinduced charge carriers, which inevitably leads to a poor visible light absorption and low quantum yield. Therefore, it is imperative to design and develop new photocatalyst with strong visible light response, high quantum yield and superior stability performances. In this work, ZnO NRAs-based hybrid photoanodes with tunable band structure, good visible light response ability and high stability were rationally designed and successfully prepared by using the chemical bath deposition, electrodeposition, solvothermal and thermal condensation methods. Accordingly, the photoelectrochemical properties were investigated systematically. Concrete research contents are as follows:?1? Double-shelled ZnO/CdS/CdSe porous NTAs composite materials were synthesized through the chemical bath deposition and electrodeposition methods. The as-prepared materials exhibit superior photoelectrochemical performance and pollutant degradation ability, which can be mainly attributed to the following aspects: stepwise band-edge structure, cosensitization effect and the porous nanotube.?2? ZnO/Cu₂O/CdS dual p-n heterostructured NRAs composite materials were prepared through the electrodeposition and chemical bath deposition methods. Compared to the ZnO and ZnO/Cu₂ O NRAs, ZnO/Cu₂O/CdS NRAs display superior water splitting performance and pollutant degradation ability, which can be ascribed to the formed dual p-n junction that provides large enough space charge region to generate abundant charge carrier; meanwhile, dual p-n heterostructure could greatly facilitate the separation and transfer of photoinduced electron-hole pairs, which should be main responsibility for the superior performances.?3? P-type BiOI NPs decorated n-type ZnO NRAs composite materials were fabricated by the electrodeposition and solvothermal process. The as-prepared p-n heterostructure shows superior photoelectrochemical performance and pollutant degradation ability, which may be attributed to the p-type BiOI serves as a sensitizer to absorb visible light and promotes electron transfer to n-type ZnO NRAs; on the other hand, ZnO NRAs provide fast electron transfer channel which can effectively inhibit the recombination rate of charge carriers, and unique layered structure of BiOI enlarges the contact area of pollutants.?4? BiOBr NPs wrapped ZnO NRAs composite materials were synthesized through the electrodeposition and solvothermal methods. Compared to the ZnO and BiOBr, ZnO/BiOBr displays enhanced water splitting performance and pollutant degradation ability, which is benefited from the formed heterostructure that not only promotes the visible light absorption but also facilitate the separation of charge carriers.?5? g-C₃N₄ decorated ZnO NRAs composite materials were prepared by using the electrodeposition and thermal condensation methods. The as-prepared material obtained obviouly promoted light response activity, which may be ascribed to the introduction of g-C₃N₄ that improves the separation and transfer efficiency of photoinduced charge carriers.