Tungsten carbide synthesized by low-temperature combustion as gas diffusion electrode catalyst

Abstract

Tungsten carbide powder, which is used as the catalyst for a gas diffusion electrode, has been prepared by low-temperature combustion synthesis for the first time. The average particle size of the prepared tungsten carbide is 200 nm, determined by X-ray diffraction and field-emission scanning electron microscopy. The effects of the carbon/tungsten (C/W) molar ratio on the formation of tungsten carbide and carbon content on the complete carbonization temperature are discussed. The optimal synthesis temperature is 1100 °C, and the optimal C/W molar ratio is 19/3. The electrocatalytic properties of tungsten carbide for the oxygen reduction reaction are evaluated through the use of polarization curves and electrochemical impedance spectroscopy in neutral and alkaline electrolytes. The current density of the tungsten carbide-based gas diffusion electrode is as high as 350 mA cm −2 at 0.4 V versus Hg/HgO. It is demonstrated that the tungsten carbide catalyst exhibits excellent electrocatalytic performance, comparable with that of Pt. • The WC particles of well-distributed and smaller size are produced by the LCS method. • The LCS method is a new direct reduction and carbonization method. • C/W mole ratio affects the formation of WC. • Carbon content affects the complete carbonization temperature.