Enzyme‐Mimicking Confined Cu–Co Dual Sites for Selective Electrocatalytic Reduction of Dilute Nitrate to Ammonia

Abstract Electrocatalytic nitrate‐to‐ammonia conversion offers a low‐carbon shortcut to traditional energy‐intensive denitrification and nitrogen fixation processes. However, challenges persist regarding sluggish reaction kinetics in environmental nitrate streams and high energy consumption in neutral media. Inspired by the structure of channels and active sites in nitrite reductase, a spatially confined copper–cobalt dual‐site catalyst (CuCo/MCS) featuring atomic‐level synergy is designed. The optimized CuCo/MCS sample achieves complete conversion of 50 mg L −1 nitrate within 150 min, with an ammonia selectivity of 91.2% while maintaining an ultra‐low energy consumption of 1.35 kWh m −3 . Notably, the nano‐confined effect enhances resistance to complexing inhibitors like SCN − , inhibition experiments confirm that proton‐coupled electron transfer is more fundamental than the reduction process mediated by atomic hydrogen. In situ FT‐IR analysis reaveals synergistic relationship between water dissociation and nitrate reduction at −0.60 V versus RHE. Theoretical calculations elucidate that electronic gains and losses around copper facilitate d–p orbital hybridization with nitrate, accelerating rate‐determining steps. Overall, this work advances rational design of catalytic systems for nitrate pollution control and resource conversion at environmental concentrations.