▎ 摘　　要

The diffusion layer is an important structure in the membrane electrode assembly (MEA) of direct methanol fuel cells (DMFCs) that provide a support layer for catalysts, electronic channels, and gas liquid mass transport channels. In this study, three types of carbon based materials were used to fabricate anode diffusion layers - carbon black Vulcan (R) (CBV), M-15 grade graphene nanosheets (GM-15) and C-500 grade graphene nanosheets (GC-500). The microporous layers of cathodes were constructed with CBV. A carbon-based microporous layer with a 2 mg cm(-2) loading was coated onto a PTFE-pretreated carbon cloth, while a Nafion-117 membrane was applied as the electrolyte to the DMFCs. Pt-Ru black and Pt black were used as anode and cathode electrode catalysts, each with loadings of 8 mg cm(-2) and 4 mg cm(-2), respectively. All tests were conducted using MEAs with active areas of 4 cm(2) and air was supplied to single cells by passive modes. Surface morphology was studied using scanning electron microscopy (SEM), which produced pictures of complex network formations within the structures. CBV consists of nanosized carbon particles, while both GM-15 and GC-500 are made of stacks of graphene sheets with flaky structures that increase catalyst utilization. Performance tests of the DMFCs were conducted using a potentiostat that generated polarization curves. The highest peak power density of 13.7 mW cm(-2) was obtained by the GC-500 anode diffusion layer using 3 M methanol as fuel. The energy efficiency of the passive DMFCs was approximately 10% with a specific energy of approximately 610 Wh kg(-1), which is higher than that of conventional lithium ion batteries, portraying the bright future of alternative energy sources for use in power applications for portable devices. The high power densities obtained by both graphenebased materials, GM-15 and GC-500, demonstrate that graphene is a material other than state of the art carbon black that has the potential to be used as a DMFC anode support material. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.