Chloride-Driven Interfacial Confinement Facilitates Adaptive Directional Electron Transfer in Hypersaline Environments.

Chloride ions (Cl-) are conventionally regarded as inhibitory species in hypersaline wastewater treatment, where they cause active-site shielding, radical scavenging, and catalyst deactivation. Contrary to this established view, we demonstrate that Cl- can transform from a passive inhibitor into an active interfacial regulatory species. We show that rather than suppressing reactivity, Cl- can reconfigure the confined solid-liquid interface to modulate charge-transfer kinetics and facilitate mass transport, establishing a new catalytic pathway. Herein, we report a Cl--driven directional coordination strategy that combines the Cl- species with the catalyst interface and oxidant to construct an adaptive electron transfer channel (AETC). Multi-scale experiments, density functional theory (DFT) calculations, and molecular dynamics simulations reveal that the Cl--driven coordination changes internal electronic interactions, modulates orbital hybridization with the oxidant, and adjusts the interfacial hydrogen-bonding network. This AETC alleviates mass-transfer constraints and suppresses catalytic deactivation, enabling accelerated degradation kinetics alongside long-term stability. Overall, this work challenges the traditional perception of Cl-, demonstrating that Cl- can drive constructive interfacial functions in extreme ionic environments.