Enhanced oxygen reduction reaction activity and durability of Pt nanoparticles deposited on graphene-coated alumina nanofibres.

Abstract

The oxygen reduction reaction (ORR) activity and stability of Pt catalysts deposited on graphene-coated alumina nanofibres (GCNFs) were investigated. The GCNFs were fabricated by catalyst-free chemical vapour deposition. Pt nanoparticles (NPs) were deposited on the nanofibres by sonoelectrochemical and plasma-assisted synthesis methods. Scanning and transmission electron microscopy analyses revealed different surface morphologies of the prepared Pt catalysts, depending on the synthesis procedure. Sonoelectrochemical deposition resulted in a uniform distribution of smaller Pt NPs on the support surface, while plasma-assisted synthesis, along with well-dispersed smaller Pt NPs, led to particle agglomeration at certain nucleation sites. Further details about the surface features were obtained from cyclic voltammetry and CO stripping experiments in 0.1 M HClO4 solution. Rotating disk electrode investigations revealed that the Pt/GCNF catalyst is more active towards the ORR in acid media than the commercial Pt/C (20 wt%). The prepared catalyst also showed significantly higher durability than commercial Pt/C, with no change in the half-wave potential after 10 000 potential cycles.