Photodeposited Cu₂O on BiVO₄ to Achieve a S-Scheme Heterojunction for Boosting Photocatalytic Water Purification

Constructing a S-scheme heterojunction is crucial for improving the separation and transfer efficiency of a photogenerated charge carrier, which is essential for effective water treatment. However, designing suitable heterojunction interfaces that facilitate efficient charge transfer remains a significant challenge. Herein, cuprous oxide (Cu₂O) was successfully photodeposited onto BiVO₄ to form a S-scheme heterojunction for photocatalytic water purification. This catalyst achieved a remarkable visible-light-driven ciprofloxacin degradation rate of 1.32 h^-1, approximately 3.88 and 66 times higher than that of pristine BiVO₄ and Cu₂O, respectively. The significantly enhanced photocatalytic activity primarily originates from the formation of a S-scheme heterostructure, which markedly accelerates exciton separation and prolongs the lifetime of charge carriers. The more negative conduction band of Cu₂O enables efficient oxygen molecular reduction to produce superoxide radicals (O₂^• -) upon integration with BiVO₄. Systematic characterization confirmed that the S-scheme charge transfer pathway significantly increased the generation of oxygen species and greatly promoted the overall photocatalytic activity. Moreover, the photocatalyst demonstrated excellent stability and recyclability, maintaining its activity without noticeable loss over multiple cycles, highlighting its strong potential for practical application. This work offers valuable insights into regulating photogenerated carrier transfer for enhanced water purification.