Ag-decorated CuO NW@TiO2 heterojunction thin film for improved visible light photocatalysis

Abstract

Herein, Ag-decorated CuO@TiO2 (CuO@TiO2-Ag) semiconductor heterojunctions are prepared using a porous CuO nanowire (NW) matrix for visible light photocatalysis applications. The CuO NW matrix is synthesized by wet-oxidation-based growth on a commercial Cu plate. Conformal coating of TiO2 on the CuO NW surfaces is successively achieved by atomic layer deposition, following which Ag nanoparticles (NPs) are deposited to synthesize a Ag-decorated CuO@TiO2 photocatalyst film. Microstructural and chemical analyses reveal uniform synthesis of a CuO@TiO2 heterojunction as well as a binding energy shift at the interface to form balanced Fermi energy, respectively. The performance of CuO@TiO2-Ag as a visible-light photocatalyst is evaluated under 20-W low-power visible-light LED illumination for the photodegradation of methylene blue. In addition, the effects of the TiO2 layer and the Ag NPs on the decomposition efficiency are investigated. To control the thickness of TiO2 and the dosage of Ag NPs, the photodegradation of CuO@TiO2-Ag is optimized at a rate of 0.0133 min -1, which is approximately 3 and 2.5 times higher than those of a bare CuO@TiO2 heterojunction and Ag-deposited CuO, respectively. The high decomposition efficiency achieved in this study results from the combined effects of the conformal core-shell heterojunction formed by atomic layer deposition and the well-distributed Ag NPs.