Regulating Local Electron Distribution of Cu Electrocatalyst via Boron Doping for Boosting Rapid Absorption and Conversion of Nitrate to Ammonia

The electrochemical reduction of nitrate to ammonia (NO₃RR) is an effective route to ammonia synthesis with the characteristics of low energy input. However, the complex multi-electron/proton transfer pathways associated with this reaction may trigger the accumulation of competitive by-products. Herein, boron (B)-doped Cu electrode (denoted as B–Cu₂O/Cu/CP) as “all-in-one” catalyst is prepared by one-step electrodeposition strategy. Caused by the B doping, the charge redistribution and local coordination environment of Cu₂O/Cu species are modulated, resulting in the exposure of active sites on the Cu₂O/Cu/CP catalyst. In-situ Fourier transform infrared spectroscopy and theoretical investigations demonstrate that both Cu₂O and Cu sites modulated by B can effectively enhance the adsorption of NO₃⁻ and facilitate the conversion of intermediate by-products, thus promoting the direct reduction of NO₃⁻ to NH₃. Consequently, a remarkable Faradaic efficiency of 92.74% can be obtained on B–Cu₂O/Cu/CP catalyst with minimal accumulation of by-products. It is expected that this work, based on the heterogeneous B doping, will open a maneuverable and versatile way for the design of effective catalysts.