Optimization of the ionomer-to-carbon ratio in the cathode catalyst layer of PtCoMn/C alloy catalysts

The optimization of membrane electrode assembly (MEA) structures based on alloy catalysts can further improve the properties of proton exchange membrane fuel cells and accelerate their commercialization. Herein, novel MEAs with ultra-low platinum loading and high performance were prepared by a decal transfer method using a highly active PtCoMn/C alloy catalyst. The effects of different I/C ratios on the performance of PtCoMn/C cathodes were investigated by polarization curves. The results suggested an optimal I/C ratio of 0.9, leading to a maximum power density of 1.51 W/cm2. The effects of the I/C ratio on catalyst activity and proton conductivity were studied by AC impedance and cyclic voltammetry, and the impact of the I/C ratio on local oxygen transport resistance was evaluated by the limiting current method. The data revealed that the MEA has the highest ECSA of CL combined with the lowest Rct and higher proton conductivity,when the I/C ratio is 0.9. An influencing mechanism of ionomer content on performance of low platinum loading MEA prepared by PtCoMn/C was then drawn, suggesting that The highest activity at the I/C ratio of 0.9 mainly depends on its excellent proton con-ductivity.