Anion-cation co-doped Cu2(OH)2CO3 enables high-efficiency electrocatalytic nitrite reduction to ammonia

The electrocatalytic nitrite reduction reaction (NO 2 RR) converts harmful nitrite in aqueous media into high value-added ammonia (NH 3 ) under mild conditions, representing a promising technology that integrates environmental remediation and green NH 3 synthesis. However, the NO 2 RR undergoes a complex process involving multi-electron/proton transfer steps. Cu-based catalytic systems are universally plagued by the inherent bottleneck of insufficient activity and selectivity, and these dual constraints can hardly be simultaneously overcome by single-element doping alone. Herein, we fabricated fluoride and cobalt co-doped Cu 2 (OH) 2 CO 3 nanosheet catalysts via a one-step hydrothermal method, where the synergistic effect between anionic and cationic dopants enables the simultaneous tailoring of the electronic structure and active site distribution of the material. Electrochemical test results demonstrate that F and Co co-doping can significantly boost the NO 2 RR catalytic performance of Cu 2 (OH) 2 CO 3 . The optimal F-3 sample achieves the highest NH 3 Faradaic efficiency (FE) of 96.47% with an NH 3 yield rate of 28.55 mg h −1 mg cat -1 at −0.8 V (vs. RHE) in 0.15 M NaNO 2 neutral electrolyte, showing a nearly 2-fold performance improvement over the undoped counterpart and outperforming most reported non-noble metal NO 2 RR electrocatalysts. This work provides a high-performance NO 2 RR electrocatalyst for neutral aqueous systems, and demonstrates that anion-cation synergistic doping can break the intrinsic performance bottleneck of Cu-based hydroxyl compounds, offering a valuable modification strategy for rational catalyst design towards electrocatalytic nitrogen-containing pollutant conversion.