Efficient Electroreduction of Nitrate to Ammonia with CuPd Nanoalloy Catalysts

Abstract The electroreduction of nitrate (NO3−) to valuable ammonia (NH3) is a green and appealing alternative to the Haber‐Bosch process. Nevertheless, this process suffers from low performance for NH3 due to the sluggish multi‐electron/proton‐involved steps. In this work, a CuPd nanoalloy catalyst was developed toward NO3− electroreduction at ambient conditions. By modulating the atomic ratio of Cu to Pd, the hydrogenation steps of NH3 synthesis during NO3− electroreduction can be effectively controlled. At −0.7 V versus reversible hydrogen electrode (vs. RHE), the optimized CuPd electrocatalysts achieved a Faradaic efficiency for NH3 of 95.5 %, which was 1.3 and 1.8 times higher than that of Cu and Pd, respectively. Notably, at −0.9 V vs. RHE, the CuPd electrocatalysts showed a high yield rate of 36.2 mg h−1 cm−2 for NH3 with a corresponding partial current density of −430.6 mA cm−2. Mechanism investigation revealed the enhanced performance originated from the synergistic catalytic cooperation between Cu and Pd sites. The H‐atoms adsorbed on the Pd sites prefer to transfer to adjacent nitrogen intermediates adsorbed on the Cu sites, thereby promoting the hydrogenation of intermediates and the formation of NH3.