Efficient Electroreduction of Nitrate to Ammonia with CuPd Nanoalloy Catalysts
Zhimin Song, Lang Qin, Yan Liu, Yongzhi Zhong, Qing Guo, Zhigang Geng, Jie Zeng
Abstract
Abstract The electroreduction of nitrate (NO 3 − ) to valuable ammonia (NH 3 ) is a green and appealing alternative to the Haber‐Bosch process. Nevertheless, this process suffers from low performance for NH 3 due to the sluggish multi‐electron/proton‐involved steps. In this work, a CuPd nanoalloy catalyst was developed toward NO 3 − electroreduction at ambient conditions. By modulating the atomic ratio of Cu to Pd, the hydrogenation steps of NH 3 synthesis during NO 3 − electroreduction can be effectively controlled. At −0.7 V versus reversible hydrogen electrode (vs. RHE), the optimized CuPd electrocatalysts achieved a Faradaic efficiency for NH 3 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 NH 3 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 NH 3 .