Impact of Heterocore Atoms on CO₂ Electroreduction in Atomically Precise Silver Nanoclusters

Abstract

Understanding the effect of internal atoms in metal nanoparticles on heterogeneous catalytic processes is crucial for achieving high activity and selectivity. This requires meticulous synthetic control over the size, composition, and atomic arrangement of nanoparticles. Here, we report the design of ligand-exchange-induced structure transformation and nanomolecule-templated atomic-level galvanic exchange strategies to synthesize PtAg 24 (IPBT) 18 (denoted as PtAg 24 ) and AuAg 24 (IPBT) 18 (denoted as AuAg 24 ) nanoclusters (NCs). Both NCs exhibit identical total metal atom and ligand (IPBT: 2-isopropylbenzenethiolate) counts, as well as atomic-level structure, except for the difference in the core atom (Pt and Au). Using these model NCs, we uncover the impact of heterocore atoms on the electrochemical CO 2 reduction reaction (eCO 2 RR) activity and selectivity. The central Pt atom in PtAg 24 is less favorable for eCO 2 RR activity, with an activity approximately 4 times smaller than that of Au in AuAg 24 . The eCO 2 RR product CO selectivity is <30% for PtAg 24, while it exceeds 70% for AuAg 24, revealing the critical role of the central atom in surface catalytic pathways. Furthermore, AuAg 24 exhibits high activity, with a CO partial current density of −202.2 mA cm –2, and stability over 24 h, retaining 90% CO selectivity in a membrane electrode assembly configuration. Operando spectroscopy and density functional theory calculations suggest the weaker adsorption of *CO intermediates and smaller energy barrier facilitate CO production on AuAg 24 compared to PtAg 24, providing valuable atomistic insights into the reaction intermediates and mechanism. The findings in this work will inspire the design of more atomically precise model nanocatalysts to explore the role of their remarkable features in the catalytic activity and selectivity for renewable energy conversion and storage.

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