Research teams at Kitami Institute of Technology, Keio University, and Institute of Industrial Science, University of Tokyo have developed iron-based superconducting materials that serve as excellent oxygen evolution catalysts.
The oxygen evolution reaction is an electrode reaction in which oxygen is generated from water, and is used in various applications in the energy field such as electrolysis of water and metal-air secondary batteries.However, the high overvoltage and large loss and the absence of a highly stable catalyst hindered its practical application.
In this study, we established a new method for synthesizing samples by controlling the amount of oxygen defects in Sr2VFeAsO3-δ, which is known as an iron-based superconductor, and made it possible to investigate the relationship between the amount of oxygen defects and catalytic performance. ..As a result, it was found that when the amount of oxygen defects in Sr2VFeAsO3-δ was larger than 0.5, the catalytic performance and catalytic stability were significantly enhanced.
When the cause was investigated by electrochemical measurement and first-principles calculation, it was found that oxygen defects are directly related to the oxygen evolution reaction.If the amount of oxygen defects is greater than 0.5, the distance between the oxygen defects will be sufficiently short, and the bonds of oxygen atoms will proceed smoothly.
Sr2VFeAsO3-δ can be said to be the first example of a multi-functional material that can be both a superconducting material and an oxygen evolution catalyst depending on the amount of oxygen defects. In 1969, John Goodenough proposed a phase diagram of superconductivity and antiferromagnetism with absolute temperature and electron correlation as parameters, but this time, 50 years have passed on a new axis called overvoltage, which was thought to be unrelated to superconductivity. In addition, the correlation between the electron magnetic function and the oxygen generation reaction function was clarified for the first time in the world.
Based on this result, superconducting materials with a sufficient amount of oxygen defects are promising candidates for oxygen evolution catalysts, and conversely, superconducting materials can be developed by modifying materials known as oxygen evolution catalysts. Although the possibility has been shown, it is expected that the development of these materials will progress dramatically in the future.
Paper information:[Journal of Materials Chemistry A] Oxygen vacancy-originated highly active electrocatalysts for oxygen evolution reaction
