Chlorine-mediated reconstruction of copper creates a tip-enriched interfacial microenvironment for deep electrochemical dechlorination

Chlorinated antibiotics are persistent halogenated pollutants whose detoxification requires deep dechlorination rather than simple parent-compound removal. Here, we report a structurally engineered, earth-abundant copper electrode (Tre-Cu) that enables rapid and deep electrochemical hydrodechlorination of chlorinated antibiotics. Prepared through a facile sequence of oxidation, in situ complex dissolution, and chloride-assisted electroreduction, Tre-Cu undergoes spontaneous surface reconstruction during operation, evolving into a spindle-shaped, sharp-tipped architecture. This electrode achieved nearly complete florfenicol removal within 20 min and full stoichiometric chloride release within 30 min under ambient air, while maintaining stable performance over 10 cycles and 36 h long-term continuous operation, as well as robust tolerance in environmental water matrices. Mechanistic studies show that dechlorination on Tre-Cu is dominated by direct electron transfer rather than atomic hydrogen-mediated reduction. Time-resolved SEM and XPS reveal that transient CuCl-like surface species drive the formation of the activated tip-rich morphology. Finite element simulations, electrochemical analysis, and DFT calculations further demonstrate that the reconstructed surface strengthens the local electric field, enriches interfacial K + , enhances pollutant adsorption, and lowers the barriers for sequential C-Cl bond cleavage. This work offers a simple strategy to couple surface reconstruction with interfacial microenvironment engineering for deep electrochemical detoxification.