High performance of low electrocatalysts loading on CNT directly grown on carbon cloth for DMFC

This study demonstrated the feasibility of a high-performance membrane-electrode-assembly (MEA), with low electrocatalyst loading on carbon nanotubes (CNTs) grown directly on carbon cloth as an anode. The direct growth of CNTs was synthesized by microwave plasma-enhanced chemical vapor deposition using CH4/H-2/N-2 as precursors. The cyclic voltammetry and electrochemical impedance measurements with 1 mM Fe(CN)(6)(3-/4-)redox reaction reveal a fast electron transport and a low resistance of charge transfer on the direct growth of CNT. The electrocatalysts, platinum and ruthenium, were coated on CNTs by sputtering to form Pt-Ru/CNTs-CC with carbon cloth for CC. Pt-Ru electrocatalysts are uniformly dispersed on the CNT, as indicated by high-resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM), because the nitrogen doped in the CNT acts as active sites for capturing electrocatalysts. The MEA, the sandwiched structure which comprises 0.4 mg cm(-2) Pt-Ru/CNTs-CC as the anode, 3.0 mg cm(-2) Pt black as the cathode and Nation 117 membrane at the center, performs very well in a direct methanol fuel cell (DMFC) test. The micro- structural MEA analysis shows that the thin electrocatalyst layer is uniform, with good interfacial continuity between membrane and the gas diffusion layer. (C) 2006 Elsevier B.V. All rights reserved.