Reformate gas composition and pressure effect on CO tolerant Pt/Ti0.8Mo0.2O2–C electrocatalyst for PEM fuel cells

Abstract Mixed-oxide coated Ti0.8Mo0.2O2–C composite supported 20 wt% Pt electrocatalysts with Ti0.8Mo0.2O2/C=75/25 mass ratio were developed for CO tolerance of polymer electrolyte membrane fuel cell (PEMFC) anode. Studies of the structure, composition and stability, as well as the results of COads stripping confirmed that the mixed oxide composite support and the electrocatalyst prepared for this study show the well-documented characteristics of the Pt/Ti1-xMoxO2-C systems with enhanced CO tolerance compared to the Pt/C catalyst. Dilution of hydrogen with CO2 and CH4 had negligible negative impact on the fuel cell performance. Switching gas composition between hydrogen and reformate shows recovery of potential after CO poisoning. Nevertheless, anode catalyst loading of 0.25 and 0.5 mgPt/cm2 was not enough to give reasonable performance when CO impurity was present. Loading of 0.85 mgPt/cm2 Ti0.8Mo0.2O2–C supported catalyst was effective to give 1000 mA/cm2 current density at 0.6 V under 25 ppm CO and 30 psig. Higher loading was needed at mass transfer limited region to overcome poisoning. However, loadings higher than 0.85 mgPt/cm2 caused mass transfer limitations. Hence higher loadings is proposed with 40 wt% Pt/Ti0.8Mo0.2O2–C support catalyst.