A novel electrocatalyst support with proton conductive properties for polymer electrolyte membrane fuel cell applications

摘要

The objective of this study is to graft the surface of carbon black, by chemically introducing polymeric chains (Nafion~® like) with proton-conducting properties. This procedure aims for a better interaction of the proton-conducting phase with the metallic catalyst particles, as well as hinders posterior support particle agglomeration. Also loss of active surface can be prevented. The proton conduction between the active electrocatalyst site and the Nafion~® ionomer membrane should be enhanced, thus diminishing the ohmic drop in the polymer electrolyte membrane fuel cell (PEMFC). PtRu nanoparticles were supported on different carbon materials by the impregnation method and direct reduction with ethylene glycol and characterized using amongst others FTIR, XRD and TEM. The screen printing technique was used to produce membrane electrode assemblies (MEA) for single cell tests in H_2 /air (PEMFC) and methanol operation (DMFC). In the PEMFC experiments, PtRu supported on grafted carbon shows 550mWcm~(-2)gmetal~(-1) power density, which represents at least 78% improvement in performance, compared to the power density of commercial PtRu/C ETEK. The DMFC results of the grafted electrocatalyst achieve around 100% improvement. The polarization curves results clearly show that the main cause of the observed effect is the reduction in ohmic drop, caused by the grafted polymer.