Nonmetallic Modified Atomically Precise Octagold Nanoclusters for Electrocatalytic Nitrate Reduction to Ammonia
Xiaojuan Zhu, Wei‐Dan Si, Kaiyu Qu, Leyang Song, Jing Wang, Yushuang Gong, Di Sun, Xiang Liu, An‐Liang Wang
Abstract
Atomically precise metal nanoclusters (NCs) with metal cores functionalized by nonmetallic elements hold great promise for electrocatalytic NO 3 – reduction reaction (NO 3 RR). However, elucidating structural evolution during catalysis and precisely identifying the active sites remain formidable challenges. Herein, we have synthesized [Au 8 S 2 (dppm) 4 ] 2+ and [Au 8 Se 2 (dppm) 4 ] 2+ (dppm: Ph 2 PCH 2 PPh 2 ) NCs with Au cores modified by S or Se atoms and subjected them to electrochemical pre-activation. Comprehensive experiments reveal that pre-activation leads to the removal of one dppm ligand from both NCs, thereby exposing metallic Au sites. As NO 3 RR catalysts, the activated [Au 8 S 2 (dppm) 4 ] 2+ achieves an NH 3 yield rate of 1108.47 mg h –1 mg Au –1 and a Faradaic efficiency of 98.34%, significantly surpassing [Au 8 Se 2 (dppm) 4 ] 2+, most reported NCs, and conventional nanocatalysts. Mechanistic studies unveil that the exposed metallic Au sites after pre-activation serve as the primary catalytic center. Furthermore, the introduction of S atoms into the Au core induces a more positive surface potential, upshifts the Au-d band center, enhances NO 3 – adsorption, and strengthens the balance between the generation and consumption of active hydrogen, collectively boosting the NO 3 RR performance. This work not only provides definitive experimental evidence for structural evolution and active-site identification in atomically precise NCs under electrolysis, but also reveals the distinct effects of different nonmetallic element modifications on catalytic performance.