Self-Assembled Pt/Mesoporous Silica−Carbon Electrocatalysts for Elevated-Temperature Polymer Electrolyte Membrane Fuel Cells

Mesoporous carbon and silica−carbon have been synthesized through a hydrogen-bonding-assisted self-assembly route as Pt electrocatalyst supports for polymer electrolyte membrane fuel cells (PEMFCs). Solid-state 1 H NMR analysis indicates the condensation of water inside the capillaries of the mesoporous structure, and the water condensation is increased by the incorporation of hydrophilic silica in the mesoporous carbon. The pore diameters of the Pt/meso-carbon and Pt/meso-SiO 2 −carbon electrocatalysts were 4.5 and 5.2 nm, respectively. The use of meso-carbon and meso-SiO 2 −carbon supports to replace conventional XC-72 carbon black significantly improves the fuel cell performance when operating at an elevated temperature of 100 °C and a reduced relative humidity of 30%. The cell assembled with the Pt/meso-SiO 2 −carbon electrocatalysts produced a maximum power density of 456 mW cm −2 at 100 °C and 30% RH, higher than 417 and 345 mW cm −2 for the cells with Pt/meso-carbon and Pt/XC-72 carbon electrocatalysts, respectively.