Synthesis and characterization of uniform nanoparticles of γ-Mo2N for supercapacitors

Uniform nanoparticles of molybdenum nitride were synthesized by temperature-programmed reaction(TPR) using MoO3 and ammonia as reactants. This material was characterized by X-ray diffractometry(XRD), transmission electron microscopy(TEM), scanning electron microcopy(SEM) and cyclic voltammetry(CV). Results show that the material consists of a pure phase of gamma-Mo2N nanoparticles with average diameter of about 16 nm. The material presents a specific capacitance of 172 F/g in 1 mol/L H2SO4 electrolyte at a scan rate of 1 mV/s and the potential window is broadened to 1.1 V (-0.6 to 0.5 V). At the 6 000th cycle, the material remains 94.9% and 94.7% of the initial capacitance in 1 mol/L H2SO4 and KCl solution, respectively. A possible mechanism comprising surface control and diffusion control is proposed to explain the effect of scan rates on specific capacitance.