Bismuth–Sulfur Engineered Zero‐Valent Iron Prioritizes Chloramphenicol‐Class Antibiotics Dechlorination Over Hydrogen Evolution and Nitro Reduction

Chloramphenicol (CAP) and florfenicol (FF), as chloramphenicol‐class antibiotics, often coexist in wastewater, where chlorine substituents largely determine their toxicity. Although zero‐valent iron (ZVI) is a promising reductive remediation material, its poor chemoselectivity and preferential electron consumption by hydrogen evolution (HER) and nitro‐reduction severely limit the detoxification of chlorinated moieties. Herein, we develop bismuth–sulfur co‐intercalated ZVI (Bi‐S‐ZVI) to reduce CAP+FF co‐contaminants, achieving enhanced nitro‐reduction (22–74‐fold), dechlorination (175–419‐fold), and low HER. Notably, the dechlorination selectivity (defined as the ratio of FF dechlorination to CAP nitro‐reduction) increased from 0.3%–2% to 39%, and Bi‐S‐ZVI enabled a distinct pathway where dechlorination preceded nitro‐reduction in the ‐NO 2 /‐Cl co‐substituted CAP molecule. Mechanistically, Bi 2 S 3 and Bi 0 are the dominant contributors to the reactivity and dechlorination selectivity of Bi‐S‐ZVI, respectively. Bi 2 S 3 couples galvanically with Fe 0 to generate a built‐in electric field and creates Fe–S–Bi charge‐transfer channels to accelerate electron transport. Bi 0 selectively associates with ─Cl as a halogen‐bond acceptor. Bi 2 S 3 and Bi 0 synergistically suppress HER by increasing surface hydrophobicity and hindering atomic hydrogen recombination, while Bi 2 S 3 further disrupts the interfacial hydrogen‐bonding network. This work provides a cost‐effective and scalable strategy for selective reductive remediation, overcoming the reactivity–selectivity–stability trade‐offs of existing iron materials.