Ampere-Level Nitrate Electroreduction to Ammonia over Monodispersed Bi-Doped FeS2

Electrochemical conversion of NO3– into NH3 (NO3RR) holds an enormous prospect to simultaneously yield valuable NH3 and alleviate NO3– pollution. Herein, we report monodispersed Bi-doped FeS2 (Bi–FeS2) as a highly effective NO3RR catalyst. Atomic coordination characterizations of Bi–FeS2 disclose that the isolated Bi dopant coordinates with its adjacent Fe atom to create the unconventional p–d hybridized Bi–Fe dinuclear sites. Operando spectroscopic measurements combined with theoretical calculations disclose that Bi–Fe dinuclear sites can synergistically enhance the hydrogenation energetics of NO3–-to-NH3 pathway, while suppressing the competitive hydrogen evolution, leading to a high NO3RR selectivity and activity. Consequently, the specially designed flow cell equipped with Bi–FeS2 exhibits a high NH3 yield rate of 83.7 mg h–1 cm–2 with a near-100% NO3–-to-NH3 Faradaic efficiency at an ampere-level current density of 1023.2 mA cm–2, together with an excellent long-term stability for 100 h of electrolysis, ranking almost the highest performance among all reported NO3RR catalysts.