Thermodynamic study and methanothermal temperature-programmed reaction synthesis of molybdenum carbide

Nanostructured molybdenum carbide（Mo2C） was successfully prepared from molybdenum trioxide（MoO 3） using methanothermal temperature-programmed reaction. Thermodynamic analysis indicated that in presence of methane, the formation of Mo2 C from MoO 3 occurs through the path of MoO 3 → MoO 2 → Mo2 C. The carburized MoO 3 was characterized using X-ray diffraction（XRD）, CHNS/O analysis, Brunauer–Emmett–Teller（BET） analysis, and field-emission scanning electron microscopy（FESEM）. At final carburization temperatures of 700 and 800°C and at methane contents ranging from 5vol% to 20vol%, Mo2 C was the only solid product observed in the XRD patterns. The results indicated that the effect of methane content on the formation of the carbide phase is substantial compared with the effect of carburization time. Elemental analysis showed that at a final temperature of 700°C, the carbon content of carburized MoO 3 is very close to the theoretical carbon mass percentage in Mo2 C. At higher carburization temperatures, excess carbon was deposited onto the surface of Mo2 C. High-surface-area Mo2 C was obtained at extremely low heating rates; this high-surface-area material is a potential electrocatalyst.