Men Yana, Men Xiaomei, Li Peng, Li Lei, Wang Xiaoyan, Su Xiaozhi, Zhang Leijie, Chen Shengli, Luo Wei
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China.
Suzhou Institute of Wuhan University, Suzhou, Jiangsu 215123, P. R. China.
J Am Chem Soc. 2025 Jun 25;147(25):21672-21685. doi: 10.1021/jacs.5c03433. Epub 2025 Jun 13.
The role of interfacial water and hydrogen-bonding structures in an electric double layer (EDL) in alkaline hydrogen oxidation reaction (HOR) kinetics has garnered widespread attention. However, the dynamic evolution of alkali metal cations (AM), as key components in EDL, and their impact on interfacial solvation structure and alkaline HOR kinetics remain poorly understood. Here, based on the NiS-island-encapsulated Ni (NiS/Ni) catalyst, we demonstrate that the AM arrangement in the EDL can be regulated by the potential of zero charge (PZC) of the electrode, which in turn controls the associated solvation environment (i.e., the ordering of interfacial water and hydrogen-bonding network). molecular dynamics simulations, surface-enhanced infrared absorption spectroscopy, and electrochemical experiments indicate that the introduction of NiS fosters a lower PZC for NiS/Ni, which thus promotes a less crowded cation arrangement and more disordered interfacial water structures, ultimately contributing to the accelerated shuttling of H/OH across the EDL through a more interconnected H-bonding network, thereby leading to a reduced energy barrier of proton-coupled electron transfer (PCET) and enhanced HOR kinetics under alkaline electrolytes. This molecular-level picture is further supported by the unconventional cation dependence of HOR activities on NiS/Ni (i.e., KOH > NaOH > LiOH) by which we reveal a new mechanistic insight; that is, the coordination of the NiS island with a partially desolvated K cation (NiS-K) promotes dynamic evolution of cation-solvated water into strongly hydrogen-bonded water on adjacent Ni, significantly accelerating the proton transfer process. This work highlights the dominant role of AM in controlling the EDL structure and PCET kinetics in alkaline HOR.
界面水和氢键结构在碱性氢氧化反应（HOR）动力学中的双电层（EDL）中的作用已引起广泛关注。然而，作为EDL关键组分的碱金属阳离子（AM）的动态演变及其对界面溶剂化结构和碱性HOR动力学的影响仍知之甚少。在此，基于硫化镍岛封装的镍（NiS/Ni）催化剂，我们证明了EDL中AM的排列可通过电极的零电荷电位（PZC）来调节，这反过来又控制了相关的溶剂化环境（即界面水的有序性和氢键网络）。分子动力学模拟、表面增强红外吸收光谱和电化学实验表明，NiS的引入使NiS/Ni的PZC降低，从而促进了阳离子排列不那么拥挤和界面水结构更无序，最终通过更相互连接的氢键网络促进了H/OH在EDL中的加速穿梭，从而导致质子耦合电子转移（PCET）的能垒降低，并增强了碱性电解质下的HOR动力学。HOR活性对NiS/Ni的非常规阳离子依赖性（即KOH > NaOH > LiOH）进一步支持了这一分子水平的图景，由此我们揭示了一种新的机理见解；即，NiS岛与部分去溶剂化的K阳离子（NiS-K）的配位促进了阳离子溶剂化水向相邻Ni上强氢键水的动态演变，显著加速了质子转移过程。这项工作突出了AM在控制碱性HOR中EDL结构和PCET动力学方面的主导作用。
