An innovative S-scheme PhC2Cu/Ag/Ag2MoO4 photocatalyst for efficient degradation of sulfamethazine antibiotics: heterojunctions and innergenerated-H2O2 promote radical production

Abstract

Copper-phenylacetylide (PhC₂Cu) is a promising candidate for photocatalysis. Herein, an S-scheme heterojunction of PhC₂Cu/Ag/Ag₂MoO₄ (PAM) photocatalyst was synthesized for the effective and stable photocatalytic reduction of sulfamethazine (SMT) under blue LED light. In the optimal PAM40 system, the kinetic rate constant for the degradation of SMT was 0.1622 min⁻¹, which was 16.3 times that of PhC₂Cu (0.0099 min⁻¹). The enhanced photocatalytic performance was attributed to efficient photoexcited charge separation, higher innergenerated-H₂O₂ and greater oxidation–reduction capacities for the generation of reactive oxygen species (ROS). The potential photocatalytic mechanism of the S-scheme PAM40 was elucidated through relevant characterization and experimental investigations, which confirmed the existence of an internal electric field (IEF), which promoted photocarrier separation and transport. The SMT degradation pathways were proposed, and the developmental toxicities of the intermediates were predicted. Moreover, this work compounded the materials with innergenerated-H₂O₂ capability (PhC₂Cu) and with H₂O₂ catalytic capability (Ag₂MoO₄), which provides an innovative perspective for the synthesis of S-scheme heterojunction photocatalysts with superior activities.