OH scavenging pyridinic N for facile oxygen reduction reaction on free Pt surface

Abstract

Compared to hydrogen oxidation reaction, oxygen reduction reaction (ORR) is a sluggish reaction in the proton exchange membrane fuel cell. Many studies have focused on the development of complex synthesis methods for new catalysts. In this study, we introduce a simple catalyst layer preparation method using an additive based on physical mixing for facile ORR in acid media. N-doped carbon containing mainly pyridinic N was used as the additive in the Pt or PtCo catalyst layer. The adjacent pyridinic N near the Pt catalyst works as a Lewis base and removes hydroxyl ions from Pt, thus leading to the simultaneous suppression of Pt oxidation. Based on electrochemical and spectroscopic analyses, we found that pyridinic N reacts with hydroxyl ions and is oxidized. Consequently, Pt catalyst without Pt oxide species exhibited higher ORR activity than pristine Pt or PtCo catalyst.