Construction of the Z-scheme Cu2O-Ag/AgBr heterostructures to enhance the visible-light-driven photocatalytic water disinfection and antibacterial performance

Abstract

Constructing Z-scheme heterojunctions is considered to be an excellent strategy for enhancing the photocatalytic performance of compounds. In this study, visible-light-driven (VLD) Z-scheme Cu2O-Ag/AgBr photocatalysts with high efficiency were constructed with the aid of a photo-reduction precipitation technique. The photocatalytic properties and different mass fractions of Ag/AgBr nanoparticles were in situ deposited on the surface of an octahedral Cu2O. The results indicated that nearly 98.7% methyl orange (MO) could be degraded within 90 min using Cu2O-Ag/AgBr. Due to the reactive oxygen species (ROS) generated by Cu2O-Ag/AgBr, 99% antibacterial efficiency was achieved by Cu2O-Ag/AgBr against Gram-positive/Gram-negative bacteria. After four consecutive cycles of Cu2O-Ag/AgBr, the photocatalyst remained relatively stable and exhibited excellent stability and reusability. Various analyses demonstrated loading Ag/AgBr nanoparticles into composites can enhance their optical properties, accelerating the transport of photogenerated carriers. The Z-scheme heterojunction between Ag/AgBr and Cu2O provided higher redox capability. Moreover, the photocatalytic properties of the composites can be boosted via the surface plasmon resonance (SPR) effect from a small amount of metallic Ag. Lastly, the mechanism of photocatalysis occurrence was elucidated by exploring the essential reaction substances in the process, and primary active species were discovered to be the photogenerated holes (h+), •O2‾, and •OH. This study indicated that the as-prepared Cu2O-Ag/AgBr exhibited great potential to be applied in wastewater treatment.