Ceria-based co-catalysts, supported on reduced graphene oxide, for the oxygen reduction in PEM fuel cells

This study proposes ceria supported on reduced graphene oxide (CeO2–rGO) as additive to platinum-on-carbon (Pt/C) catalysts, to lower Pt loading and enhance the oxygen reduction reaction (ORR) activity in proton exchange membrane fuel cells. A one-step calcination synthesis simultaneously induced oxygen vacancies in ceria and reduced graphene oxide. A comprehensive physicochemical characterization of different catalyst formulations is presented, and their electrochemical performance is discussed through ex situ tests and in situ fuel cell analyses. Rotating disk electrode studies revealed superior ORR activity for the Pt/C:CeO2–rGO 0.5:1 wt% composite with the lowest Pt content. Adopted in a 5 cm2 fuel cell under 30% relative humidity at 80°C, the same catalyst guaranteed nearly 40% higher power density versus Pt/C with double platinum loading (0.2 mgPt/cm2), and over 55% when compared to Pt/C benchmark with equal loading (0.1 mgPt/cm2), due to synergistic oxygen-vacancy and water-retention effects of defective ceria supported on rGO.