Synthesis of Electrocatalytic Tungsten Carbide Nanoparticles by High-Pressure and High-Temperature Treatment of Organotungsten Compounds.

Abstract

Metal-organic framework (MOF)-derived carbon, which contains metal nanoparticles embedded in a carbon matrix, is becoming an important group of catalysts. We report the synthesis of tungsten carbide-carbon nanocomposites using a similar concept, i.e., by pyrolysis of organotungsten compounds under high-temperature and high-pressure conditions. We characterized the product using various analytical techniques and examined its electrocatalytic activity. Two precursors, Bis(cyclopentadienyl)tungsten (IV) dichloride (Cp₂WCl₂) and Bis(cyclopentadienyl)tungsten (IV) dihydride (Cp₂WH₂) were pyrolyzed at 4.5 GPa and 600 °C. Tungsten carbide (β-WC_1-x) crystals with a size of 2 nm embedded in graphitic carbon were formed from Cp₂WH₂-derived samples. Electrochemical measurements showed that all samples were active in the oxygen reduction reaction (ORR), with the Cp₂WH₂-derived sample having the best catalytic performance.