Pore Structure and Durability Improvement of CNovel® Mesoporous Carbon as a Support Material for Pt Catalysts in Polymer Electrolyte Fuel Cells

Abstract Pore structure of mesoporous carbon (MPC, CNovel) as support material for Pt catalysts in polymer electrolyte fuel cells and durability improvement of MPC by heat-treatment were investigated. Because the primary particle size of MPC is ~2 µm, MPC is bead-milled to about 800 nm. Surface area of MPC is 1338 m2 g-1, which is comparable to that of conventional porous carbon support KB-600JD 1350 m2 g-1, while internal surface area of MPC is 1253 m2 g-1, much larger than that of KB-600JD (716 m2 g-1). Mesopore size distribution of MPC is narrower than that of KB-600JD, with central mesopore size of 4 nm. 3D-TEM analysis shows that MPC has much higher density of interconnected mesopores (2-6 nm) than KB-600JD, and cross-sectional scanning electron microscopy observations indicate that macropores (> 50 nm) coexist in MPC. These pore structures contribute to higher cell voltage of Pt/MPC over Pt/KB-600JD in the entire current density region. MPC support is heat-treated at 1800-2400℃ in Ar to improve durability against high potentials (1.0-1.5 V vs. RHE). Durability of Pt/MPC is higher than that of Pt/KB-600JD and monotonically improves with increasing heat-treatment temperature. MPC support maintains high surface area of 800 m2 g-1 even after heat-treatment at 2200°C