Electrochimica Acta, Vol.52, No.17, 5430-5436, 2007
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/H-2 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/cm(2) (current density: 15.2 mA/cm(2)) 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/cm(2)) using our setup. From the XRD data, alpha-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/cm(2) at the current density of 19.0 mA/cm(2) which was 7.3% of the 20 wt% Pt/C. (c) 2007 Elsevier Ltd. All rights reserved.
Keywords:anode;cyclic voltammetry;hydrogen oxidation;non-platinum;PEFC;power density;tungsten carbide