▎ 摘　　要

We report the direct growth of a unique all-carbon hierarchical graphene-carbon nanotube (G-CNT) hybrid structure on Toray carbon paper using chemical vapor deposition methods. Morphological characterization shows that the graphene is directly grafted onto the CNT scaffold. The hybrid possesses an ultra-high density of exposed graphene edges while retaining the porous structure of CNT scaffold. Using the G-CNT hybrid in the magnetron sputtering electrocatalyst preparation technique, an integrated, polytetrafluoroethylene binder-free cathode (Pt/G-CNT) with an ultra-low Pt loading of 0.04 mg cm(-2) is obtained. This cathode shows superior polarization performance compared to a commercial carbon black-supported Pt catalyst (Pt/VXC72) reference. (C) 2014 The Electrochemical Society. All rights reserved.