Abstract
The electrochemical conversion of nitrate (NO(3)(-)), a common nitrogen source in industrial wastewater and contaminated groundwater, into ammonia (NH(3)), signifies an approach to wastewater treatment and NH(3) production. Nevertheless, its selectivity and activity at low NO(3)(-) concentrations and industrial current densities are constrained by limited mass transfer around the electrode. Here, we report a metal-polymer bridging interface constructed by anchoring Cu/Cu(2)O nanoparticles onto a two-dimensional (2D) Cu-based benzene dicarboxylate (CuBDC) coordination polymer via in situ electroreduction (denoted as E-CuBDC). This interface weakens the electrostatic repulsion and regulates the distribution/migration of NO(3)(-) and H(2)O, creating a Janus NO(3)(-)-rich and H(2)O-poor domain near the catalyst surface. Operando characterizations and theoretical simulations indicate that the metal-polymer bridging interface selectively accumulates NO(3)(-) and reduces the energy barrier toward the reduction of *NH(2)OH to *NH(2), overcoming the mass transfer limitations at a low NO(3)(-) concentration. E-CuBDC exhibits a high Faradaic efficiency (FE) of over 90% across wide NO(3)(-) concentrations (7.1-100 mM NO(3)(-)) and high applied voltages. Additionally, it achieved stable NH(3) production over 100 h at ampere-level current densities. When applied in a Zn-NO(3)(-) system, this newly developed E-CuBDC catalyst demonstrates an outstanding power density and FE for NH(3) production, showcasing its great potential for large-scale electrochemical conversion and storage systems. This study presents a generalizable strategy for constructing metal-polymer interfaces to regulate interfacial mass transport.