Wang Zhenxiang, Chen Ming, Wu Jiedu, Ji Xiangyu, Zeng Liang, Peng Jiaxing, Yan Jiawei, Kornyshev Alexei A, Mao Bingwei, Feng Guang
Huazhong University of Science and Technology, State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Wuhan 430074, China.
Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen, China.
Phys Rev Lett. 2025 Jan 31;134(4):046201. doi: 10.1103/PhysRevLett.134.046201.
Constant-potential molecular dynamics (MD) simulations are indispensable for understanding the structure, capacitance, and dynamics of electrical double layers (EDLs) at the atomistic level. However, the classical constant-potential method, relying on the so-called "fluctuating charges" to keep electrode equipotential, overlooks quantum effects on the electrode and always underestimates EDL capacitance for typical metal electrode and aqueous electrolyte interfaces. Here, we propose a constant potential method accounting for electron spillover on the outermost nuclei of the electrode. For EDLs at Au(111) electrodes, our MD simulation reveals bell-shaped capacitance curves in magnitude and shape both quantitatively consistent with experiments. It unveils the electrode-polarization-dependent local electric fields, agreeing with experimental observations of redshift vibration of interfacial water under negative polarization and predicting a blueshift under positive polarization, and further identifies geometry dependence of two timescales during charging.
恒电位分子动力学（MD）模拟对于在原子水平上理解双电层（EDL）的结构、电容和动力学是必不可少的。然而，传统的恒电位方法依靠所谓的“波动电荷”来保持电极等电位，忽略了电极上的量子效应，并且对于典型的金属电极和水性电解质界面总是低估EDL电容。在此，我们提出一种考虑电极最外层原子核上电子溢出的恒电位方法。对于金（111）电极上的双电层，我们的MD模拟揭示了电容曲线在幅度和形状上均与实验定量一致的钟形曲线。它揭示了与电极极化相关的局部电场，与负极化下界面水的红移振动的实验观察结果一致，并预测正极化下会发生蓝移，并且进一步确定了充电过程中两个时间尺度的几何依赖性。
