Construction of LSPR enhanced Ag/Cu2O/CuO Z-scheme heterojunction films and their superior photocatalytic redox activity

Traditional methods, including wet chemistry, annealing, and photoreduction, were employed to prepare Ag/Cu₂O/CuO composite films. Analysis indicates that the Cu₂O/CuO heterojunction films were formed after wet chemical treatment and annealing. After the photoreduction reaction, Ag⁰ nanoparticles and nanosheets modified the Cu₂O/CuO heterojunction films at the nano and micro scales. The Ag modification not only enhanced the absorption of solar light of the heterojunction but also improved the transfer and separation of photogenerated electrons within the heterojunction, primarily attributed to the localized surface plasmon resonance (LSPR) effect of elemental silver. Compared to Cu₂O/CuO films, the performance of Ag/Cu₂O/CuO films in the photocatalytic degradation of MB increased by up to two times, while the performance in the photocatalytic reduction of Cr⁶⁺ improved by up to 2.56 times. Through the analysis of the charge transfer pathways of photogenerated electrons and holes within this system, we propose that the heterojunction formed between Cu₂O and CuO is of the Z-type. This study will provide valuable guidance for the design of highly efficient copper-based photocatalysts.