Theoretical Approach and Recent Understanding of Water (Photo-) Electrolysis by Dr. Katsushi Fujii
NTU MSE Seminar Hosted by Nanyang Assistant Professor Wu Dongshuang
Abstract
Recent electrochemical systems increasingly involve complex multi-electron and hybrid electrochemical–chemical reactions, especially for the CO2 reduction reaction. In this seminar, we re-evaluate the fundamental principles that are believed to be useful for electrochemical reactions. In addition, cases are discussed where classical electrochemical theory alone is insufficient.
In the first part, we discuss electron-transfer concepts and energy diagrams in electrochemistry and photoelectrochemistry. Group-III nitride photoelectrochemical water splitting is discussed as an example. We also discuss the dissolution behaviour of n-type GaN and compare it with predictions from the Gerischer model.
In the second part, we extend this discussion to polymer electrolyte membrane water electrolysis (PEMWE). We show that the efficiency and durability of PEMWE are strongly influenced not only by catalytic properties but also by cell structure. This is explained by mass-transport phenomena, for which a complete theoretical framework has yet to be established. Examples of the effect of the catalyst surroundings on CO2 reduction are also introduced. Through these examples, the seminar aims to highlight the limitations of conventional electrochemical theory and the need to integrate chemical engineering considerations into the understanding of modern electrochemical systems.
Biography
Dr. Katsushi Fujii
RIKEN Center for Advanced Photonics (RAP), Japan
Katsushi Fujii (Ph. D. Science) graduated from Osaka University in 1983 (B.Eng) and received Ph. D. degree from Osaka University in 1994. He joined Mitsubishi Chemical Corporation, in 1983. From 2004 to 2017, He had several experiences as a research institute and university researcher, Associate Professor, and Professor.
Since 2017, he has been a Research Scientist at the Centre for Advanced Photonics, RIKEN. His current areas of research interest are energy storage systems, energy conversion (water electrolysis and electrochemical CO2 reduced reaction), and material recycling.