Effect of surface oxygen functionalization of carbon support on the activity and durability of Pt/C catalysts for the oxygen reduction reaction

Abstract

Oxygen functionalization of carbon supports has been a widely used strategy to enhance catalytic performance of carbon supported Pt (Pt/C) catalysts. However, the effect of oxidative functionalization on the catalytic performance of Pt/C catalysts for the oxygen reduction reaction (ORR) has rarely been investigated. We report the impact of oxygen functionalization of carbon black (CB) supports on the activity and durability of CB supported Pt catalysts for the ORR. Pristine and mildly oxygen-functionalized CB supported Pt catalysts (Pt/CB and Pt/CB_O, respectively) show nearly identical structural parameters, including surface areas and pore volumes of the CB support, and supported Pt particle sizes. The Pt/CB_O catalyst shows higher electrochemically active surface area and ORR activity than Pt/CB catalyst, which is likely caused by differing interfacial structure between the carbon support and Pt nanoparticles in the two catalysts. In ORR durability tests, Pt/CB exhibits significantly higher stability than Pt/CB_O. Spectroscopic characterizations reveal that oxygen functionalization in the Pt/CB_O catalyst partially oxidizes the Pt nanoparticles, triggering facile dissolution and Ostwald ripening of Pt nanoparticles, which accelerates the decline of the ORR activity of Pt CB_O.