Effect of tungsten source on dispersion and electrocatalytic property of tungsten carbide

Tungsten carbide (WC) can be used as electrocatalyst of fuel cells for its like-Pt catalytic ability, CO anti-poisoning ability and high electric conductivity. It also can be expected to replace or partly replace noble metal catalyst because of its special morphology, reduced diameter and improved surface area. Ammonium metatungstate, sodium tungstate and ammonium paratungstate are respectively used as tungsten source, carbon nanotubes are used as carrier, citric acid is used as complexing agent, and tungsten acid and carbon nanotubes composite can be prepared after hydrothermal reaction. The tungsten source would be reduced into tungsten oxide as air pumped into reaction chamber at 600 ℃ by temperature-controlled program. And the obtained tungsten oxide can be further carbonized and changed to WC at 950℃ with nitrogen as atmosphere. The WC using ammonium metatungstate as tungsten source possesses the best dispersion and the smallest size. After the platinum nanoparticles are loaded on the surface of the obtained WC, the results demonstrated that the higher electrocatalytic activity (32.59 mA/cm²) in sulfuric acid solution of the Pt-WC prepared by using ammonium tungstate as tungsten source than those of sodium tungstate (11.32 mA/cm²) and ammonium paratungstate (5.13 mA/cm²), and higher electrocatalytic activity (106.92 mA/cm²) in methanol and sulfuric acid solution of the Pt-WC prepared by using ammonium tungstate as tungsten source than those of sodium tungstate (90.13 mA/cm²) and ammonium paratungstate (72.15 mA/cm²).