Abstract: Tungsten carbide (WC) nanocrystals were prepared by a solvothermal method using Mg as the reductant and WO3 and anhydrous ethanol as the precursors. The effect of time and temperature on the synthesis of WC was investigated and a probable formation mechanism was discussed. The obtained WC crystals were characterized byX-raydiffraction, transmission electron microscopy, energy dispersive spectroscopy, and electrochemical methods. Hexagonal WC was successfully prepared when the temperature was as low as 500 ℃. The content of carbon was more than that of W and the composition of the treated sample was C and WC only. The diameter of WC nanocrystals was ranged from 40 to 70 nm and the crystal was dispersed on C films. The WC nanocrystals promoted the Pt/C electrocatalyst ability obviously for the oxygen reduction reaction with the onset potential over 173 mV, which was more positive compared with that of the traditional Pt/C electrocatalyst.

Key words: solvothermal method, nanocrystal, tungsten carbide, electrocatalysis, oxygen reduction