Boron-induced electron localization in Cu nanowires promotes efficient nitrate reduction to ammonia in neutral media

Abstract

Electrochemical nitrate reduction is regarded as a sustainable alternative approach for the synthesis of ammonia. It is important to design and develop advanced electrocatalysts to improve the nitrate reduction to ammonia (NRA) activity. Herein, an efficient boron-doped copper nanowire electrocatalyst, B-Cu NWs/CF, for the NRA was successfully synthetized. The incorporation of electron deficient boron atoms into copper nanowires resulted in the electron localization with the partially empty Cu 3d orbitals and improved significantly the catalytic activity of Cu active sites. The FE, nitrate conversion rate, the ammonia selectivity, and yield rate for the NRA catalyzed by B-Cu NWs/CF achieved 94.41 ± 0.12 %, 100.02 ± 0.94 %, 96.58 ± 1.5 %, and 0.276 ± 0.00296 mmol·h−1·cm−2, respectively, remarkably superior to those of the pristine Cu NWs/CF and most of recently reported copper-based catalysts. And B-Cu NWs/CF exhibited the outstanding stability with high activity. The DFT calculations confirmed that the incorporation of boron into copper nanowires effectively inhibited the hydrogen evolution and the production of other reaction by-products. Importantly, the incorporation of boron significantly enhanced the adsorption of the *NO3 intermediate on the copper surface and greatly reduced the activation barrier of *NO→*HNO. This work presents a new idea to devise highly active catalysts by the incorporation of nonmetal to adjust the activity of the NRA and inhibit the production of by-products.