Understanding the Role of Potential and Cation Effect on Electrocatalytic CO2 Reduction in All-Alkynyl-Protected Ag15 Nanoclusters

Yuping Chen; Xia Zhou; Xunying Liu; Zhenghua Tang; Likai Wang; Qing Tang

doi:10.1021/jacs.4c15112

Understanding the Role of Potential and Cation Effect on Electrocatalytic CO₂ Reduction in All-Alkynyl-Protected Ag₁₅ Nanoclusters

J Am Chem Soc. 2025 Jan 8. doi: 10.1021/jacs.4c15112. Online ahead of print.

Authors

Yuping Chen¹, Xia Zhou², Xunying Liu³, Zhenghua Tang³, Likai Wang², Qing Tang¹

Affiliations

¹ School of Chemistry and Chemical Engineering, Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Chongqing 401331, China.
² School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, Shandong 255049, China.
³ New Energy Research Institute, School of Environment and Energy, Guangzhou Higher Education Mega Center, South China University of Technology, Guangzhou 510006, China.

PMID: 39772524
DOI: 10.1021/jacs.4c15112

Abstract

Atomically precise metal nanoclusters (NCs) have emerged as an intriguing class of model catalysts for electrochemical CO₂ reduction reactions (CO₂RR). However, the interplay between the interface environment (e.g., potential, cation concentration) and electron-proton transfer (ET/PT) kinetics─particularly in alkynyl-protected metal NCs─remains poorly understood. Here, we combined first-principles simulations and electrochemical experiments to investigate the role of potential and cation effect on CO₂RR performance in a prototype all-alkynyl-protected Ag₁₅(C≡C-CH₃)⁺ cluster. Our simulations revealed that the applied reduction potential triggers the elimination of the alkynyl ligand via sequentially breaking two π-type Ag-C bonds and one σ-type Ag-C bond to expose the catalytically active Ag sites, and the barrier of the Ag-C breakage monotonically decreases with the lowering in potential. Furthermore, we show that introducing the inner-sphere Na⁺ ions greatly enhances *CO₂ activation and promotes proton transfer to generate *COOH and *CO by forming the Na⁺-CO₂(*COOH) complexes, while the competitive hydrogen evolution reaction (HER) from water dissociation is greatly suppressed, thus dramatically improving the selectivity of CO₂ electroreduction. The electrochemical measurements further validated our predictions, where the CO Faradaic efficiency (FE_CO) and current density (j_CO) show a pronounced dependence on the Na⁺ concentration. At an optimal concentration of 0.1 M NaCl, FE_CO can reach up to ∼96%, demonstrating the crucial role of cations in promoting the CO₂RR. Our findings provide vital insights into the atomic-level reaction mechanism of the CO₂RR on alkynyl-protected Ag₁₅ NCs and highlight the important role of potential and electrolyte cation in governing the electron/proton transfer kinetics.