Chen Yuping, Zhou Xia, Liu Xunying, Tang Zhenghua, Wang Likai, Tang Qing
School of Chemistry and Chemical Engineering, Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Chongqing 401331, China.
School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, Shandong 255049, China.
J Am Chem Soc. 2025 Jan 22;147(3):2699-2713. doi: 10.1021/jacs.4c15112. Epub 2025 Jan 8.
Atomically precise metal nanoclusters (NCs) have emerged as an intriguing class of model catalysts for electrochemical CO reduction reactions (CORR). 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 CORR performance in a prototype all-alkynyl-protected Ag(C≡C-CH) 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 *CO activation and promotes proton transfer to generate *COOH and *CO by forming the Na-CO(*COOH) complexes, while the competitive hydrogen evolution reaction (HER) from water dissociation is greatly suppressed, thus dramatically improving the selectivity of CO electroreduction. The electrochemical measurements further validated our predictions, where the CO Faradaic efficiency (FE) and current density () show a pronounced dependence on the Na concentration. At an optimal concentration of 0.1 M NaCl, FE can reach up to ∼96%, demonstrating the crucial role of cations in promoting the CORR. Our findings provide vital insights into the atomic-level reaction mechanism of the CORR on alkynyl-protected Ag NCs and highlight the important role of potential and electrolyte cation in governing the electron/proton transfer kinetics.
原子精确的金属纳米团簇（NCs）已成为一类用于电化学CO还原反应（CORR）的有趣的模型催化剂。然而，界面环境（例如，电势、阳离子浓度）与电子-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。在这里，我们结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在原型全炔基保护的Ag(C≡C-CH)团簇中对CORR性能的作用。我们的模拟表明，施加的还原电势通过依次断裂两个π型Ag-C键和一个σ型Ag-C键来触发炔基配体的消除，从而暴露出催化活性的Ag位点，并且Ag-C键断裂的势垒随着电势的降低而单调降低。此外，我们表明引入内球Na离子极大地增强了CO活化，并通过形成Na-CO(COOH)络合物促进质子转移以生成COOH和CO，同时来自水离解的竞争性析氢反应（HER）被大大抑制，从而显著提高了CO电还原的选择性。电化学测量进一步验证了我们的预测，其中CO法拉第效率（FE）和电流密度（）对Na浓度有明显的依赖性。在0.1 M NaCl的最佳浓度下，FE可高达~96%，证明了阳离子在促进CORR中的关键作用。我们的研究结果为炔基保护的Ag NCs上CORR的原子级反应机理提供了重要见解，并突出了电势和电解质阳离子在控制电子/质子转移动力学中的重要作用。
