A N,P-co-doped 3D graphene/cobalt-embedded electrocatalyst for the oxygen reduction reaction

The development of highly-efficient oxygen reduction reaction (ORR) catalysts is of great importance but remains challenging for energy applications including fuel cells and metal-air batteries. In this study, novel hybrids composed of Co nanoparticles and N,P co-doped graphene aerogels are successfully synthesized by combining a hydrothermal method with the subsequent pyrolysis procedure. Our fabricated Co/N, P-GA-900 possesses a high BET surface area (619 m(2) g(-1)) with hierarchical porous structures. For the electrocatalytic evaluation of the ORR in an alkaline medium, the onset potential (-0.04 vs. SCE) and the half-wave potential (-0.18 V vs. SCE) of the Co/N, P-GA-900 catalyst are determined to be very close to those (-0.01 and -0.16 V vs. SCE) of the commercial Pt/C catalyst. The methanol tolerance and operational stability of Co/N, P-GA-900, however, are superior to those of commercial Pt/C. The high catalytic activity and excellent durability of our as-obtained Co/N, P-GA-900 arise from hierarchical porous structures of graphene aerogels and synergetic effects between multiple types of active sites, including metallic Co nanoparticles, nitrogen and phosphorus dopants. The work presented here provides a new platform for an attractive Pt-free catalyst for fuel cells.