Development of mean-field QM/MM method for atom-scale investigation of electrochemical interfaces

Abstract

Recently, as renewable energy systems have been in the spotlight as alternatives to fossil fuels, research on the development of energy storage and conversion devices based on electrochemistry has been actively conducted. The electrochemical reaction at complex interfaces is not only difficult to understand the mechanism, but also an underlying concept, a structure of the electrical double layer, has not been clearly identified. Therefore, in order to build a renewable energy-based society, a deep understanding of electrochemistry must precede. To this end, this research deals with the development of mean-field QM/MM methodology that could simulate an electrochemical interface at an atomic scale and its application to various problems. First, the DFT-CES, one of the mean-field QM/MM methods, was modified to solve the problems when each QM and MM region are not electrically neutral so it can be applied to study the electrochemical systems. Next, the electrical double layer structure, one of the long-standing problems, was elucidated at the atomic scale. Lastly, a mechanism of electrochemical CO$_2$ reduction to CO was established and the origin of the cation-dependent reaction activity was revealed.