Refining the active phases of silver/nickle-based catalysts achieves a highly-selective reduction of nitrate to ammonium at low overpotential

• Published in: Applied catalysis. B, Environmental Vol. 356; p. 124224
• Main Authors: Jiang, Yingyang, Kong, Deqing, Huang, Longlong, Wu, Shilu, Xu, Peng, Ye, Ling, Zhou, Xuemei, Qian, Jinjie, Tang, Hao, Ge, Yongjie, Guan, Jia, Yang, Zhi, Nie, Huagui
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-11-2024
• Subjects: Ag/Ni/Ni(OH)2 NWs; Ammonia; Electrocatalysis; Hads-mediated pathway; Nitrate reduction; Electrocatalysis; Ammonia; Ag/Ni/Ni(OH)2 NWs; Hads-mediated pathway; Nitrate reduction
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2024.124224

The electrocatalytic conversion of NO3‾ to NH3 (NO3RR) with elevated activity and exceptional selectivity at low potential remains a formidable challenge. Herein, the A-Ag@Ni/Ni(OH)2 NWs with atomic-level Ag/Ni interfaces were synthesized via electrochemical activation of Ag@Ni/Ni(OH)2 NWs at −1.05 V vs. RHE for 1 hour, and subsequently employed for electrocatalytic NO3RR. Specially, Ag sites could afford active centers for the adsorption of NO3‾ and convert it to NO2‾. Furthermore, Ni/Ni(OH)2 sites as vibrant centers for electrocatalytic H2O splitting, generating atomic H on the catalyst surface (Hads), thereby facilitating the rapid conversion of NO2‾ to NH3 via the Hads-mediated pathway. DFT calculations further substantiate that the Hads-mediated pathway is thermodynamically more favorable than the electron reduction pathway, the former of which facilitates the generation of NH3 and is an energy-efficient process, thus, the A-Ag@Ni/Ni(OH)2 NWs show outstanding electrocatalytic activity and selectivity for NO3‾-to-NH3 transformation at low potential.
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•The A-Ag@Ni/Ni(OH)2 NWs with atomic-level Ag/Ni interfaces have been synthesized for electrocatalytic NO3RR.•The Ag sites could afford active centers for the adsorption of NO3‾ and convert it to NO2‾.•Ni/Ni(OH)2 sites as vibrant centers for generating Hads, facilitating the conversion of NO2‾ to NH3 via the Hads-mediated pathway.•The Hads-mediated pathway is kinetically and thermodynamically more favorable than the electron reduction pathway.