Facile hydrothermal synthesis and electrochemical properties of (NH4)2V4O9 sheets for supercapacitor electrode with excellent performance

A facile and versatile method for synthesis of novel ammonium vanadium oxide [(NH4)(2)V4O9] sheets is developed by a simple hydrothermal route. It is found that the synthetic conditions play an important role in the successful synthesis of (NH4)(2)V4O9 sheets, and the favorable condition is NH(4)Vo(3)/H2C2O4 center dot 2H(2)O = 1/1 at 180 degrees C for 48 h. (NH4)(2)V4O9 sheets exhibit the square-like shape with several nanometers in thickness, BET specific surface area of 16 m(2) g(-1) and pore volume of 0.16 cm(3) g(-1) Electrochemical properties of (NH4)(2)V4O9 sheets are firstly investigated as supercapacitor electrodes by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). (NH4)(2)V4O9 sheets exhibit electrical storage based on the faradaic mechanism with excellent capacity and rate capability. Specific capacitance of (NH4)(2)V4O9 sheets reaches to 249F g(-1) at a current density of 0.5 A g(-1), suggesting that (NH4)(2)V4O9 sheets can be promising potential as electrode material applied to supercapacitors. (C) 2018 Elsevier B.V. All rights reserved.