重庆大学唐青团队报道了电位和阳离子效应在全炔基保护Ag15纳米团簇电催化CO₂还原中的作用。相关研究成果发表在2025年1月8日出版的《美国化学会杂志》。

原子精确的金属纳米簇（NCs）已成为电化学CO₂还原反应（CO₂RR）的一类有趣的模型催化剂。然而，界面环境（如电势、阳离子浓度）和电子-质子转移（ET/PT）动力学之间的相互作用，特别是在炔基保护的金属NCs中，仍然知之甚少。

研究人员综合第一性原理模拟和电化学实验，研究了电势和阳离子效应对原型全炔基保护的Ag₁₅（C≡C–CH₃）+团簇中CO₂RR性能的作用。模拟表明，施加的还原电位通过顺序断裂两个π型Ag-C键和一个σ型Ag-C链以暴露催化活性Ag位点，引发炔基配体的消除，Ag-C断裂的势垒随着电位的降低而单调降低。

此外，研究发现，引入内层Na⁺大大增强了*CO₂的活化，并通过形成Na⁺-CO₂（*COOH）络合物促进质子转移产生*COOH和*CO，同时大大抑制了水解离的竞争性析氢反应（HER），从而显著提高了CO₂电还原的选择性。

电化学测量进一步验证了该预测，其中CO法拉第效率（FECO）和电流密度（jCO）显示出对Na⁺浓度的明显依赖性。在0.1 M NaCl的最佳浓度下，FECO可以达到～96%，这表明阳离子在促进CO₂RR中起着至关重要的作用。

附：英文原文

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

Author: Yuping Chen, Xia Zhou, Xunying Liu, Zhenghua Tang, Likai Wang, Qing Tang

Issue&Volume: January 8, 2025

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 (FECO) and current density (jCO) show a pronounced dependence on the Na+ concentration. At an optimal concentration of 0.1 M NaCl, FECO 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.

DOI: 10.1021/jacs.4c15112

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c15112