Redox supercapacitor performance of nanocrystalline molybdenum nitrides obtained by ammonolysis of chloride- and amide-derived precursors

Reactions of MoCl5 or Mo(NMe2)(4) with ammonia result in cubic lambda-Mo2N or hexagonal delta(1)-MoN depending on reaction time and temperature. At moderate temperatures the cubic product from Mo(NMe2)(4) exhibits lattice distortions. Fairly high surface areas are observed in the porous particles of the chloride-derived materials and high capacitances of up to 275 F g(-1) are observed when electrodes made from them are cycled in aqueous H2SO4 or K2SO4 electrolytes. The cyclic voltammograms suggest charge is largely stored in the electrochemical double layer at the surface of these materials. Amide-derived molybdenum nitrides have relatively low surface areas and smaller capacitances, but do exhibit strong redox features in their cyclic voltammograms, suggesting that redox capacitance is responsible for a significant proportion of the charge stored. (C) 2014 Elsevier B.V. All rights reserved.