High-performance Ag NPs@Cu-ZIF-8 membrane electrode for selective electrochemical separation and resourceful transformation of bromide from aqueous brine

Ag NPs@Cu-ZIF-8: ZIF-8 modified by partial Cu 2+ doping and Ag NPs loading. • The electrode maintains 128.2 mg・g −1 capacity after 10 Br − cycles. • At optimal conditions, the electrode achieves 147.2 mg·g −1 maximum Br − capacity. • DFT proves Cu 2+ -Ag modification enhances Br − adsorption. Bromide ions (Br − ) are finite and non-renewable strategic resources, and their highly selective recovery is of great significance for the sustainable utilization of brine resources and ecological environmental protection. To address the shortcomings of conventional adsorbents such as poor electrical conductivity and insufficient active sites, an Ag NPs@Cu-ZIF-8 composite was successfully constructed via a synergistic modification strategy involving copper framework doping and silver nanoparticle loading in this study. The composite not only retains the inherent porous structural advantages of ZIF-8 but also effectively overcomes its poor electrical conductivity. Systematic material characterizations combined with density functional theory (DFT) calculations were employed to reveal the microscopic adsorption mechanism of the composite toward Br − in aqueous solution. The results demonstrate that the introduction of silver nanoparticles significantly enhances the electrical conductivity of the material and provides abundant active adsorption sites for Br − capture. Electrochemical test results reveal that the Ag NPs@Cu-ZIF-8 membrane electrode achieves a maximum bromide adsorption capacity of 147.2 mg·g −1 under optimal experimental conditions. The adsorbed bromide can be converted into elemental bromine through extraction, realizing efficient resource recovery. Cycling experiments indicate that the adsorption capacity only drops from 139.7 mg·g −1 to 93.5 mg·g −1 after ten adsorption-desorption cycles under conventional conditions, which reflects outstanding cycling stability. This material presents prominent advantages for the green and efficient recovery of bromine resources. Download: Download high-res image (104KB) Download: Download full-size image