High performance polymer electrolyte membrane fuel cells (PEMFCs) with gradient Pt nanowire cathodes prepared by decal transfer method

A gradient Pt nanowire (Pt-NW) cathode with a promoted mass transfer and Pt utilization was developed by decal transfer method. The relationships of Pt loading and ionomer content with electrode performance were investigated by electrode structure characterization and testing in polymer electrolyte membrane fuel cell (PEMFC). The results show that an increasing Pt loading can improve the catalytic kinetic performance of Pt-NW electrode, but too higher a Pt loading leads to serious aggregation and thus low catalyst utilization. A similar trend was found to the ionomer content sprayed onto the Pt-NW cathode. The ionomer extends the triple-phase boundary (TPB), but excessive amount would cover part of the catalyst active sites and hinder the mass transfer. The optimal performance of the Pt-NW cathode is achieved at 0.30 mg_Pt cm^-2 and 33 wt% ionomer, where a maximum power density of 0.93 W cm^-2 is obtained, which is better than the state-of-the-art commercial gas diffusion electrode (GDE) with 0.40 mg_Pt cm^-2.