Fundamental Studies on Electrode Reactions Involving Oxygen, Carbon, and Hydrogen for Energy and Environmental Technologies

Abstract

In biological metabolism, the conversion of materials and energy involving hydrogen, carbon, and oxygen occurs efficiently under ambient temperature and pressure conditions. For instance, in photosynthesis, the H2O oxidation and the NADP+ reduction make a pair, ultimately transforming CO2 into organic substances. In oxygenic respiration, the oxidation of organic substances is coupled with the O2 reduction, providing the energy necessary to sustain life processes. Hydrogen-oxidizing bacteria synthesize organic substances from CO2, utilizing H2 as the reducing agent. Understanding the nature of these material transformations in biological processes, which are based on redox reactions, is valuable for advancing electrochemical technologies, including fuel cells, H2O electrolysis, CO2 electrolysis, air batteries, and artificial photosynthesis. The author has extensively conducted fundamental researches on electrode reactions, including H2 evolution, H2 oxidation, O2 reduction, H2O oxidation, CO2 reduction, and oxidation of organic substances, based on these basic concepts. The individual studies cover a broad spectrum of fields. While these studies are interdependent for the author, it is difficult to systematically compile these interdisciplinary research results into a single article. Therefore, the focus of this article is put on presenting the results of fundamental researches on lithium-air batteries, which is a part of the electrode reaction research that the author has been conducting.

Keywords

• energy technologies
• environmental technologies
• secondary batteries