Abstract
Catalyst layers (CLs) are designed using a specific ionomer in accordance with the required mass transport. Although the ionomer is needed as the protonic conductor, an excess thereof prevents oxygen diffusion. This work investigates the effect of using a SiO2 coating and a low amount of ionomer on the performance of a polymer electrolyte fuel cell (PEFC). The application of a SiO2 coating to the catalyst surface is expected to change its surface characteristics and enhance the dispersion of the catalyst in the ink. In terms of their particle distribution, catalysts coated with SiO2 maintain a higher dispersivity than commercial Pt/C with a low amount of ionomer. The structure of the CLs was investigated by examining the effects of various amounts of ionomer in the presence and absence of SiO2 coating by studying the cross-sectional morphology of the CLs with focused ion beam-scanning electron microscopy (FIB-SEM).