International Journal of Hydrogen Energy, Vol.45, No.3, 1867-1877, 2020
Improvement of cell performance in catalyst layers with silica-coated Pt/carbon catalysts for polymer electrolyte fuel cells
Carbon-supported Pt catalysts (Pt/Cs) for use of cathode catalyst layers (CLs) for PEFCs were covered with silica layers in order to improve performance. CLs with low ratio of ionomer to carbon (I/C) for Pt/C and silica-coated Pt/C were fabricated using an inkjet printing (denoted as Pt/C(IJ) and SiO2-Pt/C(IJ)) to reduce oxygen diffusion resistance. Compared to Pt/C(IJ), SiO2-Pt/C(IJ) ink maintained good dispersion and high stability under the lower I/C. The performance of SiO2-Pt/C(IJ) was significantly higher than Pt/C(IJ) at 0.6 V under all humidity conditions. In particular, the performance of SiO2-Pt/C(IJ) under low humidity conditions showed noticeable improvement regardless of current density area. From FIB-SEM, it was confirmed that the morphologies and porosities of both catalysts were the same. Thus, these results indicate that oxygen diffusion resistance, related to structure of CLs, hardly affects the performance, whereas improved performance is attributed to increased proton conductivity by silica layers containing hydrophilic groups. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.