In Situ Epitaxial Growth of a Lattice Matched BiO _2‐x /BiOCl Heterojunction for Efficient Photocatalytic Degradation of Emerging Organic Contaminants: Enhanced Exciton Dissociation and Reactive Species Generation

ABSTRACT During photocatalytic emerging organic contaminants degradation, bismuth oxyhalides typically exhibit limited exciton dissociation, resulting predominantly in the generation of ¹ O ₂ that is insufficient for deep oxidation of pollutants. Although constructing lattice‐matched bismuth oxyhalide‐based heterojunctions represents an effective strategy to enhance exciton separation and reactive oxygen species generation, achieving such constructions under mild synthetic conditions remains a challenge. Here, we successfully synthesize a lattice‐matched BiO _2‐x /BiOCl (BO/BOC) heterojunction of 99.63% using a simple light‐triggered in situ growth strategy in NaCl solution, which degrades 95.6% bisphenol A (BPA), representing a 4.79 fold enhancement over the NaCl‐free control. Besides, BO/BOC‐2 causes more severe degradation of low‐density polyethylene (LDPE) than BiO _2‐x and BiOCl, as evidenced by pronounced morphological damage and the formation of oxygen‐containing groups (O─H, C═O) in LDPE. Detailed characterization and experimental results indicate that this high photocatalytic activity stems from the built‐in electric field (IEF) at the in situ grown BO/BOC Z‐scheme heterojunction interface, which promotes the dissociation of excitons into carriers and the generation of ·O ₂ ⁻ and ·OH. This study provides a feasible strategy for the rational design of Z‐scheme heterojunctions, highlighting the crucial role of interface engineering in regulating exciton dynamics and promoting charge separation to enhance the photocatalytic performance.