水溶液中金属零电荷的潜力的建立：从头算分子动力学模拟揭示出不同的水面,The Journal of Physical Chemistry C

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水溶液中金属零电荷的潜力的建立：从头算分子动力学模拟揭示出不同的水面
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2021-02-12 , DOI: 10.1021/acs.jpcc.0c11089
Peng Li ₁ , Jun Huang ₂ , Youcheng Hu ₁ , Shengli Chen ₁

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以水为界面的Pt（111）和Au（111）作为模型系统，从头进行分子动力学模拟，研究了金属与水的相互作用，旨在了解界面水分子调节零电荷（PZC）电势的机理。水溶液中的金属电极。区分了几种金属与水的相互作用，并通过仔细关联界面原子和电子结构来量化它们对金属功函数（WF）的影响。界面水分子的第一层具有O-down构型，并通过Pauli斥力，配位键和次要偶极子方向增加近表面电子密度，从而显着降低金属WF。相比之下，由于金属与氢键的相互作用和偶极子的取向，第二溶剂化层中的氢向下构型的水分子增加了金属的WF。涉及第二层的还有没有优选取向并且仅充当氢键连接体的水分子。它们对金属电极的电子结构的影响可忽略不计。引入化学吸附氢（H_ad）具有不同的覆盖率，可调节金属与水的相互作用，从而导致金属WF的非单调变化。所获得的原子学见解不仅有助于阐明长期以来通过溶剂化使金属电极的PZC显着降低的难题，而且还使我们对金属-溶液界面的行为（例如，电势和吸附物-依赖的界面电容。

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Establishment of the Potential of Zero Charge of Metals in Aqueous Solutions: Different Faces of Water Revealed by Ab Initio Molecular Dynamics Simulations

Metal–water interactions are investigated using ab initio molecular dynamics simulations performed on water-interfaced Pt(111) and Au(111) as model systems, aiming at understanding the mechanism of interface water molecules to regulate the potential of zero charge (PZC) of metal electrodes in aqueous solutions. Several metal–water interactions are distinguished, and their effects on the metal work function (WF) are quantified through carefully correlating the interfacial atomic and electronic structures. The first layer of interface water molecules possesses an O-down configuration and significantly lowers the metal WF by increasing the near-surface electron density through Pauli repulsion, coordination bonding, and subordinate dipole orientation. In contrast, the H-down-configured water molecules in the second solvation layer increase the metal WF due to the metal–hydrogen bonding interaction and dipole orientation. Involved in the second layer are also water molecules that have no preferred orientation and merely act as hydrogen bond linkers. They negligibly affect the electronic structure of metal electrodes. Introducing chemisorbed hydrogen (H_ad) with varying coverages modulates the metal–water interactions, resulting in a nonmonotonic variation of the metal WF. The atomic insights obtained not only help to enunciate the long-standing puzzle of a significant decrease in the PZC of metal electrodes by solvation but also add to our understanding of the behaviors of metal–solution interfaces, for examples, the potential- and adsorbate-dependent interfacial capacitance.

更新日期：2021-02-25

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