Applicability of group 4 oxides to oxygen reduction electrocatalysts for protonic-conducting ceramic fuel cells operated at intermediate temperature

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05257
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 36020:Energy-related chemistry
• Research Institution: Yokohama National University
• Principal Investigator: Ishihara Akimitsu 横浜国立大学, 先端科学高等研究院, 特任教員(教授) (30754006)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 中温型燃料電池 / 酸素還元触媒

Outline of Final Research Achievements

In recent years, ceramics with high proton conductivity in the medium temperature range of 250-500°C have been developed. However, the reaction rate of the oxygen reduction reaction occurred at cathode side is slow, resulting in lower energy conversion efficiency. Therefore, it is essential to develop catalysts that are stable in the medium temperature range and exhibit high oxygen reduction activity. In this study, first a cell for electrochemical evaluation was developed and a cell with a simple structure was realized. Using this cell, the oxygen reduction activity of various catalysts including noble metals was evaluated, and it was found that noble metal catalysts such as platinum inhibit oxygen reduction in liquid electrolytes due to the progressive formation of oxides. On the other hand, when using ceramics electrolytes, the noble metal catalysts were able to achieve equilibrium potentials, indicating that they can be good quality active points.

Free Research Field

エネルギー変換化学

Academic Significance and Societal Importance of the Research Achievements

本研究によって開発した電気化学セルにより、これまで行われていなかった中温域での触媒材料の電気化学特性評価が比較的簡便に可能となった。このセルにより新規触媒開発が加速される。また、中温域での液体電解質とセラミクス電解質では、材料の安定性が大きく異なることがわかった。特に貴金属触媒では、セラミクス電解質を用いた場合には、安定であり、さらに酸素還元反応の理論電位を示すことがわかった。このことは、貴金属触媒は高い酸素還元触媒能を有することを示しており、触媒層の構造を制御して、大きな電流を取り出せるようにすれば、高効率でのエネルギー変換が可能であることを示唆している。