Tadashi Ogitsu
Lawrence Livermore National Laboratory, USA
Title: Atomistic insights into electrochemical interfaces by ab-initio simulations and in-situ characterizations
Biography
Biography: Tadashi Ogitsu
Abstract
Recent progresses in ab-initio computer simulation techniques as well as the advancement in high performance computing made direct simulations of complex systems such as electrochemical interfaces possible. Faithful modeling of electrochemical interface, however, is still very challenging partly due to lack of experimental probe that provides direct atomistic structural information. However, there are experimental characterization techniques that give us information about local chemical environment. In this presentation, we will first discuss about our recent experience in using ab-initio simulations for interpreting ambient-pressure X-ray photoemission spectroscopy (AP-XPS) results on III-V semiconductors (GaP/InP) exposed to chemical agents such as oxygen and/or water. XPS spectrum is usually analyzed based on comparison to reference information available in literature, which is valid if the system of our interest can be well approximated as a linear combination of well-defined reference problems, which is unlikely to be the case for electrochemical systems where local chemical environments tend to be dynamical in nature. Ab-initio simulations provide information regarding relation between thermodynamic stability of structural motifs and their spectroscopic signatures, therefore, peak assignment can be performed in a more rational and robust fashion. In addition, one may combine multiple theoretical and experimental spectroscopic information for the same system and may examine the consistency of each analysis. Development of accurate and realistic structural models of complex electrochemical systems will give us atomistic insights on electrochemical processes such as hydrogen/oxygen evolution and/or material corrosions, which in turn, can be used to improve the performances of energy conversion/storage devices.