Granda-Marulanda Laura P, McCrum Ian T, Koper Marc T M
Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands.
Department of Chemical & Biomolecular Engineering, Clarkson University, 8 Clarkson Ave., Potsdam, NY 13699, United States of America.
J Phys Condens Matter. 2021 Apr 27;33(20). doi: 10.1088/1361-648X/abf19d.
Determining the adsorption potential of adsorbed ions in the field of computational electrocatalysis is of great interest to study their interaction with the electrode material and the solvent, and to map out surface phase diagrams and reaction pathways. Calculating the adsorption potentials of ions with density functional theory and comparing across various ions requires an accurate reference energy of the ion in solution and electrons at the same electrochemical scale. Here we highlight a previously used method for determining the reference free energy of solution phase ions using a simple electrochemical thermodynamic cycle, which allows this free energy to be calculated from that of a neutral gas-phase or solid species and an experimentally measured equilibrium potential, avoiding the need to model solvent around the solution phase ion in the electronic structure calculations. While this method is not new, we describe its use and utility in detail and show that this same method can be used to find the free energy of any ion from any reaction, as long as the half-cell equilibrium potential is known, even for reactions that do not transfer the same number of protons and electrons. To illustrate its usability, we compare the adsorption potentials obtained with DFT of I, Br, Cl, and SOon Pt(111) and Au(111) and OHand Agon Pt(111) with those measured experimentally and find that this simple and computationally affordable method reproduces the experimental trends.
在计算电催化领域确定吸附离子的吸附势对于研究它们与电极材料和溶剂的相互作用、绘制表面相图以及反应路径具有重要意义。用密度泛函理论计算离子的吸附势并在各种离子之间进行比较，需要在相同的电化学尺度下准确确定离子在溶液中的参考能量以及电子的参考能量。在此，我们重点介绍一种先前使用的方法，即利用简单的电化学热力学循环来确定溶液相离子的参考自由能，这使得该自由能能够从气相或固相中性物种的自由能以及实验测量的平衡电位计算得出，从而避免了在电子结构计算中对溶液相离子周围溶剂进行建模的需求。虽然这种方法并非新颖，但我们详细描述了它的用法和效用，并表明只要知道半电池平衡电位，即使对于质子和电子转移数不同的反应，该方法也可用于从任何反应中找到任何离子的自由能。为了说明其可用性，我们将用密度泛函理论得到的I、Br、Cl和SO在Pt(111)和Au(111)上以及OH和Ag在Pt(111)上的吸附势与实验测量值进行比较，发现这种简单且计算成本低的方法能够重现实验趋势。
