Carbon-supported Mo2C electrocatalysts for hydrogen evolution reaction

Abstract

Molybdenum carbide (Mo₂C) nanoparticles supported on two different carbon materials, carbon nanotubes and carbon xerogel, were prepared and characterised using X-ray diffraction, thermogravimetric analysis, scanning and transmission electron microscopy, nitrogen sorption and X-ray photoelectron spectroscopy. The analyses showed similar composition (ca. 27 wt% of Mo₂C) and crystallite size (22–28 nm) for the two samples, but significantly different morphologies and specific surface areas. These were subsequently tested as electrocatalysts for hydrogen evolution reaction (HER) in acid media. Using linear scan voltammetry and electrochemical impedance measurements the main reaction parameters were determined, including Tafel slope, charge transfer coefficient and exchange current density. Capacitance properties were examined and correlated with the electrocatalysts activity for HER. The stability of the two materials was also investigated and proved to be very good.