In situ constructing of ultrastable ceramic@graphene core-shell architectures as advanced metal catalyst supports toward oxygen reduction

Abstract

The changeable structure of 2D graphene nanosheets makes the Pt-based nanoparticles (NPs) possess a low efficiency toward oxygen reduction reaction (ORR) and a short lifetime for proton exchange membrane fuel cells. Thus, a unique TiC@graphene core-shell structure material with low surface energy is designed and prepared by an in situ forming strategy, and firstly applied as a stable support of Pt NPs. The as-prepared Pt/GNS@TiC catalyst presents a high activity. Especially, its ORR stability is remarkably improved. Even after 15000 potential cycles, the half-wave potential and mass activity toward ORR have almost no change. This can be attributed to that the graphene nanosheet existing in a sphere shape effectively avoids the restacking or folding caused by the giant surface tension in 2D graphene nanosheets, impeding the decrease of the triple-phase boundary on Pt NPs. Significantly, the power density of fuel cells with our novel catalyst reaches 853 mV cm–2 under a low Pt loading (0.25 mgPt cm–2) and H2/Air conditions. These indicate the new ceramic@graphene core-shell nanocomposite is a promising application in fuel cells and other fields.