Tungsten and nickel tungsten carbides as anode electrocatalysts

Tungsten and nickel tungsten carbides were evaluated as the anode catalysts of a polymer electrolyte fuel cell (PEFC). These catalysts were prepared by the temperature-programmed carburization of tungsten and nickel tungsten oxides from 573 to 873-1073 K in a stream of 20% CH₄/H₂ and kept at temperature for 3 h. The 30% tungsten and nickel tungsten carbides mixed with Ketjen carbon (KC) were evaluated by cyclic voltammetry and linear sweep voltammetry using a rotating disk electrode and electrocatalytic activity (I-V performance) using a single cell. The W1023/KC catalyst achieved a power density of 6.4 mW/cm² (current density: 15.2 mA/cm²) which corresponded to 5.7% of that achieved by a commercial 20% Pt/C catalyst in a single cell (20% Pt/C: 111.7 mW/cm²) using our setup. From the XRD data, α-W₂C together with a small amount of WC was active during the anodic oxidation. The maximum power density of the 30 wt% 873 K-carburized NiW/KC was 8.2 mW/cm² at the current density of 19.0 mA/cm² which was 7.3% of the 20 wt% Pt/C.