Unlocking superior chloride ion capture in silver/porous carbon nanoarchitectures through MOF-templated galvanic replacement and heterointerface engineering

The efficient capture of chloride ions (Cl − ) from industrial effluents remains a significant challenge, constrained by both the intrinsic characteristics of Cl − and the inadequacies of conventional treatment methods. Herein, we present a MOF-templated galvanic replacement strategy to synthesize ultrafine Ag nanoparticles spatially confined within a MOF-derived porous carbon (Ag/PC). As a Faradaic anode in a hybrid capacitive deionization (HCDI) system, Ag/PC achieves exceptional Cl − electrosorption performance, delivering exceptional specific adsorption capacities (90.5 mg g −1 at 1.2 V; 154.7 mg g −1 at 1.6 V), outstanding energy efficiency (0.38–0.43 Wh g −1 ) and remarkable long-term cycling stability (89.0 % retention after 100 cycles). Comprehensive in situ and ex situ characterizations reveal a dynamic and reversible Ag/AgCl phase transformation governing the Cl − electrosorption process. Density functional theory (DFT) calculations further highlight that the Ag/PC heterointerface promotes electronic coupling and induces a favorable d-band center shift, facilitating charge transfer and lowering the energy barrier for Cl − capture. This study provides fundamental insights into Faradaic Cl − storage mechanisms and outlines a versatile paradigm for the rational design of high-performance electrodes for industrial wastewater treatment technologies. • A MOF-templated galvanic replacement strategy constructs Ag nanoparticles confined in porous carbon. • Ag/PC achieves large Cl − capacity (154.7 mg g −1 ) and low energy efficiency (0.38 Wh g −1 ). • In situ/ex situ characterizations and calculations demonstrate the reversible Ag/AgCl phase transformation mechanism.