Effect of the Solvent on the Oxygen Evolution Reaction at the TiO2-Water Interface

We investigate the solvation effect of water on the overpotentials of the oxygen evolution reaction on rutile TiO2 by applying the thermodynamic integration method on atomistic model interfaces with and without the water molecules. We compare the results at the vacuum interface with the commonly used computational hydrogen electrode method, finding overall good agreement. The effect of the solvent is found to be twofold. First, the explicit treatment of the solvent can lead to equilibrium configurations differing from the relaxed structures without solvent. Second, the overpotentials can be affected by up to 0.5 eV. The energetics are subject to electrostatic effects at the interface rather than to modifications in the hydrogen bond network. These results provide a promising perspective for treating the solvent with implicit models.

本研究通过在有无水分子的原子尺度模型界面上应用热力学积分法（thermodynamic integration method），探究了水对金红石相二氧化钛（rutile TiO₂）表面析氧反应（oxygen evolution reaction, OER）过电位的溶剂化效应。我们将真空界面下的计算结果与常用的计算氢电极法（computational hydrogen electrode method）所得结果进行对比，发现二者整体吻合度优异。溶剂的影响可归结为两个方面：其一，对溶剂的显式处理会使得平衡构型与无溶剂条件下弛豫得到的结构存在差异；其二，过电位可受到最高达0.5电子伏特（eV）的调控。该体系的能量学主要受界面处的静电效应支配，而非氢键网络的结构变化。本研究结果为采用隐式溶剂模型处理溶剂化效应提供了颇具前景的研究思路。