Novel Non-Stoichiometric Tungsten Oxide Based Catalyst Support for the Increased CO Tolerance in PEMFC

Abstract

Cost and durability are two major factors that delay large-scale production and commercialization of PEMFC’s. One of the technologically ready application of the proton exchange membrane fuel cells (PEMFC) is in the combined heat and power systems (µCHP), which are used in the individual households or buildings. The performance of the µCHP systems greatly depends on the purity of the hydrogen stream, which is produced via methane reforming process. To overcome low CO tolerance of the commercially used Pt electrocatalyst and to lower the catalyst content we have prepared non-stoichiometric tungsten oxide as a Pt based catalyst support. We have prepared several catalysts designated as 10% Pt/WO3-C, 20% Pt/WO3-C, 40% Pt/WO3-C. The structure and morphology characteristics of the prepared catalysts were investigated using XRD, TEM and SEM/EDX techniques. Investigations concerning electroactivity of these catalysts towards the hydrogen oxidation reaction (HOR) were performed using cyclic voltammetry, linear sweep voltammetry, forming an ultra thin catalyst layer onto RDE. Mechanism and the kinetics of the prepared catalysts towards HOR were evaluated and if was found that increased mass activity of the 10% Pt/WO3-C could be attributed to the interactive naure of the WO3 catalyst support. Obtained results clearly show increased CO tolerance of Pt/WO3-C catalyst compared to commercial Pt/C, which was confirmed by lowering the stripping potential of the CO, adsorbed on the surface of the 10% Pt/WO3-C. catalyst is more facile than that on commercial 40% Pt/C. These catalysts were employed as anode catalyst in the MEA, and the performance of single cell PEMFC were compared to commercial catalyst.