The effects of silica-coated Pt catalysts (SiO2/Pt/C) were investigated by experimental measurements and numerical analysis in order to obtain manufacturing guidelines by designing optimized catalyst layers (CL) for polymer electrolyte fuel cells. The silica-coated Pt catalysts with hydrophilic silica layers were experimentally prepared and measured by a single cell. Experimental results showed lower performance of SiO2/Pt/C than non-coated Pt catalysts (Pt/C) under relative humidity (RH) of 80% at 80°C. In the simulation of the SiO2/Pt/C, two parameters including the enhancement of proton conductivity and an increase in the oxygen diffusion resistance in the CL, attributed to silica layers, were added. The distribution of current density at 0.8 A/sq cm of the SiO2/Pt/C at each humidity condition (100%RH, 80%RH, 60%RH, 40%RH) was more homogeneous and reached closer to the gas diffusion layer compared to those of the Pt/C. The result indicates that it is possible to improve durability by increasing the reaction located near the polymer electrolyte membrane. For both catalysts, the overvoltages at 0.8 A/sq cm were similar to each other, except for that of proton resistance in ionomer and oxygen diffusion in the ionomer.
All Science Journal Classification (ASJC) codes
- 化学 (全般)