Graphene coupled MoO3 films prepared by wetting-induced climbing and key role of graphene on photocatalytic activity enhancement

Abstract

Because of its unique physical and chemical characteristics, such as excellent electrical conductivity, wide-range light absorption, and strong chemical adsorption, graphene was used to couple with the MoO3 films prepared by anodization followed by annealing to improve their photocatalytic performance using a novel thin-film composite method, called the wetting-induced climbing method. These composite films were analyzed by XRD, SEM, XPS, UV–vis spectroscopy, and EIS spectra. The XRD, SEM, and XPS analysis results show that the graphene/MoO3 composite films were prepared. The light absorption capacity of these composite films was greatly enhanced. The bandgap values were decreased due to the graphene coupling and crystal defects in the MoO3 films. The EIS spectra indicate that the photogenerated charge carriers were easier to transfer to the coupled graphene, which worked as the acceptor and transferred medium of photo-induced electrons owing to the graphene coupling. The graphene coupling amount has a moderate and optimum value to improve photocatalytic activity. Too many graphene platelets would shield the greater surface area of MoO3 films and thus reduce the number of photo-inspired carriers, leading to fewer oxidizing species. The number reduction of graphene layers has no positive effect on improving photocatalytic activity. The photocatalytic activity of the graphene/MoO3 composite films is 2.62 times that of the individual MoO3 films.