Presentation Information
[3E11]Spin-polarized pz frontier states as electronic descriptors for acidic oxygen reduction on metal-free carbon catalysts
*Kenji Hayashida1, Bang Lu1, Ray Miyazaki1, Kenji Iida1, Satoru Takakusagi1, Kotaro Takeyasu1 (1. Institute for Catalysis, Hokkaido University (Japan))
Oxygen reduction reaction (ORR), in which O2 is reduced to H2O, is a key cathodic reaction in fuel cells. Although Pt-based catalysts are highly active for ORR, their cost and poisoning sensitivity motivate the development of metal-free carbon catalysts. However, because carbon materials lack transition-metal d orbitals, the origin of O2 activation in acidic electrolytes remains unclear. Here, we investigate graphene oxide-derived carbon catalysts with tunable defect densities to clarify how local electronic states govern ORR activity. Magnetization, spectroscopy, and electrochemical measurements reveal that defect reconstruction disrupts the π-conjugated framework and generates localized spin states. ORR activity strongly correlates with spin density. Density functional theory calculations indicate that spin-polarized pz frontier states formed near defects hybridize with O2 π* orbitals, promoting electron transfer and C-O bond formation. These results show that defect-induced localized pz states provide metal-like O2 activation in carbon materials, providing a design principle for metal-free electrocatalysts.
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