Novel [111] oriented γ-Mo2N thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

Abstract

The γ-Mo2N thin films were deposited using reactive dc magnetron sputtering, and tested as an electrode material in an aqueous solution of Li2SO4 with a working potential window of 0.05V∼-0.85V versus SCE. The morphology, structure and electrochemical properties were systematically studied for the films of different deposition conditions. It was found that the electrochemical property of the γ-Mo2N film depends not only on the deposition temperature but also on the nitrogen concentration in Ar-N2 gas mixture. The sample deposited for 1h at 400°C with nitrogen concentration x=0.35 shows a dense microstructure and strong (111) texture. It exhibits the best electrochemical property, with a high volumetric capacitance of 722Fcm−3 at 5mVs−1, moderate rate capability with a relaxation time constant of 220ms, and excellent cycling stability of 100% capacitance retention after 2000 cycles. The (111)-oriented γ-Mo2N film is suggested to be a promising candidate of anode materials for micro-electrochemical-capacitors.