Cu₂O/WO₃ S-scheme heterojunctions for photocatalytic degradation of levofloxacin based on coordination activation

Heterogeneous photocatalytic degradation of antibiotic involves the activation of antibiotic molecules and the photocatalytic oxidation process. However, the simultaneous improvement of these processes is still a challenge. Herein, S-scheme heterojunctions consisted of Cu₂O nanocluster with defective WO₃ nanosheets were constructed for efficient photocatalytic degradation of levofloxacin (LVX). The typical CNS-5 composite (5 wt% Cu₂O/WO₃) achieves an optimal LVX degradation efficiency of 97.9% within 80 min. The spatial charge separation and enhancement of redox capacity were realized by the formation of S-scheme heterojunction between Cu₂O and WO₃. Moreover, their interfacial interaction would lead to the loss of lattice oxygen and the generation of W⁵⁺ sites. It is witnessed that the C-N of piperazine ring and CO of carboxylic acid in LVX are coordinated with W⁵⁺ sites to build the electronic bridge to activate LVX, greatly promoting the further degradation. This work highlights the important role of selective coordination activation cooperated with S-type heterojunctions for the photocatalytic degradation and offers a new view to understand the degradation of antibiotics at molecular level.