Sputter-Deposited Binder-Free Nanopyramidal Cr/γ-MoN TFEs for High-Performance Supercapacitors.

Due to their outstanding power density, long cycle life and low cost, supercapacitors have gained much interest. As for supercapacitor electrodes, molybdenum nitrides show promising potential. Molybdenum nitrides, however, are mainly prepared as nanopowders via a chemical route and require binders for the manufacture of electrodes. Such electrodes can impair the performance of supercapacitors. Herein, binder-free chromium (Cr)-doped molybdenum nitride (MoN) TFEs having different Cr concentrations are prepared via a reactive co-sputtering technique. The Cr-doped MoN films prepared have a cubic phase structure of γ-MoN with a minor shift in the (111) plane. While un-doped MoN films exhibit a spherical morphology, Cr-doped MoN films demonstrate a clear pyramid-like surface morphology. The developed Cr-doped MoN films contain 0-7.9 at.% of Cr in MoN lattice. A supercapacitor using a Cr-doped MoN electrode having the highest concentration of Cr reveals maximum areal capacity of 2780 mC/cm, which is much higher than that of an un-doped MoN electrode (110 mC/cm). Furthermore, the Cr-doped MoN electrode demonstrates excellent cycling stability, achieving ~ 94.6% capacity retention for about 2000 cycles. The reactive co-sputtering proves to be a suitable technique for fabrication of binder-free TFEs for high-performance energy storage device applications.