Coupling Co, N Co-Doped Carbon Nanotubes and PtCo Nanoparticles for Boosting Oxygen Reduction Reaction

The exploitation of an efficient and stable oxygen reduction reaction (ORR) catalyst plays a crucial role in the slow kinetics of the cathode in proton exchange membrane fuel cells. In this study, a catalyst loaded with PtCo alloys on Co and N co-doped carbon nanotubes (PtCoNC) is synthesized for oxygen reduction reaction, which has high activity and stability. The carbon nanotube structure provides efficient transport channels for reactant exchange and product transport, as well as provides a wealth of triple-phase sites, that improves the utilization of Pt. Further, the PtCoNC catalyst exhibits robust metal-support interactions, which can be attributed to the anchoring of the Co-N_x sites to Pt. Theoretical calculations indicating an increase in binding energy and a reduction in layer spacing provide conclusive verification of the presence of augmented interactions between PtCo nanoparticles and the support. As a result, the low Pt-loaded (0.025 mg cm^-2) PtCoNC catalyst demonstrates superior ORR activity to that of commercial Pt/C with an impressive half-wave potential of 0.893 V vs reversible hydrogen electrode (RHE) in 0.1 M HClO₄ solution. At 0.9 V vs RHE, its mass activity and specific activity are 3 and 2.6 times that of commercial Pt/C, respectively. It also shows better stability in acidic environment.