Fuel cell performance of membrane electrode assembly with PDAC/sPPO self-assembly layer containing Pt-Ru catalyst on proton exchange membrane surface

Abstract

In this study, 5, 10, and 15 bi-layers of poly(diallyl dimethyl ammonium chloride) (PDAC)/sulfonated-poly(2,6-dimethyl 1,4-phenylene oxide) (sPPO) containing Pt55-Ru45 catalyst are self-assembled on both sides of the proton exchange membrane (PEM) (i.e. Nafion-117) using a layer-by-layer technique to serve as the membrane electrode assembly (MEA) for a direct methanol fuel cell (DMFC). Experimental results show that the XC-72 carbon particles with Pt55-Ru45 alloy catalyst in the sPPO layer penetrated the PDAC layers forming a continuous catalyst layer throughout the self-assembly PDAC/sPPO bi-layers. This continuous catalyst layer structure provides a conductive media and transfer channel for the produced electrons and protons in the catalyst layer to the external circuit and the PEM and cathode sides. Our self-assembly MEAs have higher mass catalyst activity than the MEA prepared by the conventional method under CH3OH/O2 fuel cell testing, i.e., 1588.8 (5 bi-layers), 1205.8 (10 bi-layers), and 350.0Ag−1 Pt-Ru (15 bi-layers) vs. 80.0Ag−1 Pt-Ru (for conventional MEA), respectively. The 10 bi-layers of PDAC/sPPO sample loaded with 0.017mg Pt-Ru cm−2 catalyst had the highest power density of 3.70mWcm−2 (@0.18V) and 74.1mWcm−2 (@0.40V) under the CH3OH/O2 and H2/O2 fuel cell operating at 80°C, respectively.