Pore structure control of support-free catalyst utilizing neither platinum nor carbon and the performance enhancement of the catalyst layer for fuel cells

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06180
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Hirosaki University
• Principal Investigator: Chisaka Mitsuharu 弘前大学, 理工学研究科, 准教授 (20513310)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 酸素還元 / 酸化チタン / 窒化チタン / カソード

Outline of Final Research Achievements

Oxide catalysts have been developed in polymer electrolyte fuel cell cathodes to replace platinum-group-metal catalysts, while both the oxygen reduction reaction activity and the surface area remained moderate. In this study, the pore structure of titanium oxide catalysts was controlled by two methods; the one is the use of silica templates and the other is codoping of phosphor and nitrogen atoms.
The latter significantly enhanced the activity and increased the surface area. A recently reported facile combustion method was modified by simply adding H3PO4 to the precursor dispersion. Pentavalent phosphor atoms were doped into both the bulk and surface to form new active sites without alternating the number of oxygen vacancy on the surface rutile TiO2, which was formed by nitrogen-doping. The catalyst loading was reduced to less than half of the previous phosphor-free catalysts while the activity was successfully enhanced by the phosphor-doping.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

固体高分子形燃料電池正極に用いられている白金系触媒の希少性と、炭素担体の低い耐久性は、燃料電池車の本格普及に対する大きな障壁と考えられてきた。白金系触媒と炭素担体のいずれも用いない酸化物系材料は、燃料電池正極で安定であるものの、性能と比表面積が低いことが課題だった。新たにリン原子を酸化チタン相へ置換導入することにより、その性能と比表面積のどちらも向上することを初めて見出した点が、本研究の学術的意義である。上述した本格普及に対する二つの課題を解決し得る材料を、安価で簡易な手法で合成した点が社会的な意義である。