Design and depositing composition gradient functional metal oxide films via Solution Precursor Plasma Spray Process

As well-know, excellent photocatalytic activity exhibiting good visible light response, photochemical stability and slow recombination of photogenerated hole and electrons seem impossible to be achieved by single metal oxide semiconductor (MOS) material. Therefore, using mixture of various MOS could benefit advantages of each oxide for better photocatalytic performance. Firstly, the energy bandgaps for different composition gradient binary metal oxides were predicted using the “first principle calculation method”. Then, based on these simulation results, selective three kind mixture material coating systems (including ZnO/Co₃O₄, ZnO/Fe₂O₃ and Co₃O₄/Fe₂O₃) with relative narrowing bandgap were prepared via a facile effective single-step Solution Precursor Plasma Spray route, which were tested with SEM, XRD and UV-Vis. Besides, with the same composition gradient, effects of substrate preheating temperature and thickness of each layer on corresponding properties of films were characterized as well. In addition, photocatalytic degradation performances for each kind gradient material film system were evaluated under different light irradiations. This pioneer work demonstrates that preparing composition gradient MOS films provides a promising strategy for improved photogradation performance.

Keywords: Solution precursor plasma spray, Composition gradient films, First principle calculation method, Bandgap, Microstructure, Photocatalytic degradation