Interfacial chemical‐bonded Fe(III)/CdIn ₂ S ₄ with boosted charge carrier transfer for efficient O ₂ activation

Abstract Photocatalysis is hindered by inefficient charge carrier separation and transfer, which result in poor photocatalytic performance. Herein, an interfacial Fe‐S chemical‐bonded Fe(III)/CdIn 2 S 4 photocatalyst was designed and synthesized via a facile impregnation method. The Fe(III) species chemical‐bonded on the surface of CdIn 2 S 4 facilitate the electron transfer from CdIn 2 S 4 to Fe(III) cluster, achieving the boosted O 2 molecule activation for ciprofloxacin (CIP) photocatalytic degradation. Under visible‐light irradiation, the optimal 15%Fe(III)/CdIn 2 S 4 yielded a CIP degradation rate and mineralisation degree of 98.9% and 74.5%, respectively. The apparent kinetic constant ( k app, min −1 ) for CIP degradation was 3.66 times larger than that of pristine CdIn 2 S 4 . Notably, the degree of CIP mineralisation surpassed those of most reported photocatalysts. The regulatory effects of Fe(III) on the interfacial electronic structure of CdIn 2 S 4 were further confirmed using Kelvin probe force microscopy, in ‐situ X‐ray photoelectron spectroscopy, and density functional theory calculations. Furthermore, the boosted charge separation and transfer for O 2 molecule activation mechanisms were also elucidated. In addition, a photocatalytic degradation pathway for CIP and its potential ecotoxicological effects were proposed. The findings of this study provide a new strategy for regulating the interfacial electronic structure of catalysts to improve their photocatalytic performance.