Preparation of Novel Cu/Cu2O Composite Thin Films by Pulse Deposition Method and Their Enhanced Photocatalytic Performance for Methylene Blue

Cu/Cu2O 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/Cu2O composite thin films for methylene blue was studied. The results showed that the prepared Cu/Cu2O 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 Cu2O. The carrier concentration, photocurrent and open-circuit voltage of Cu/Cu2O increased, and the alternating current impedance obviously decreased. Compared with pure Cu2O, Cu/Cu2O with a pulse time of 85-5 s had good photocatalytic performance. The recombination of Cu allows the photogenerated electrons on the Cu2O conduction band to be quickly transferred to the Cu surface, which promotes the effective separation of photogenerated charge on the Cu2O 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.