Preparation of Novel Cu/Cu <sub>2</sub> O Composite Thin Films by Pulse Deposition Method and Their Enhanced Photocatalytic Performance for Methylene Blue
Xiaojiao Yu, Xiaoyi Zheng, Yuchen Wei, Jin Wang, Ningning Zhao, Qian Yang, Zhong Yu, Jinfen Niu
Abstract
Cu/Cu 2 O composite thin films were prepared by pulsed electrodeposition in a single electrolyte solution. The microstructure and performance of the composite thin films were tested and analysed. The photocatalytic performance of Cu/Cu 2 O composite thin films for methylene blue was studied. The results showed that the prepared Cu/Cu 2 O was a triangular pyramid with a (111) plane preferential orientation, the grain size was approximately 500–1000 nm, and the band gap width was wider than that of pure Cu 2 O. The carrier concentration, photocurrent and open-circuit voltage of Cu/Cu 2 O increased, and the alternating current impedance obviously decreased. Compared with pure Cu 2 O, Cu/Cu 2 O with a pulse time of 85–5 s had good photocatalytic performance. The recombination of Cu allows the photogenerated electrons on the Cu 2 O conduction band to be quickly transferred to the Cu surface, which promotes the effective separation of photogenerated charge on the Cu 2 O surface. After the stability test, the degradation rate of methylene blue was almost unchanged after 5 cycles. Methylene blue degradation process studies have shown that active hydroxyl free radicals and holes play a main role. Twelve types of degradation of intermediate products were determined, and the possible paths of MB degradation were proposed. The research results could be used to provide a new way of thinking for the treatment of refractory organic compounds in water environments.