Facile synthesis of ZnWO4 nanowall arrays on Ni foam for high performance supercapacitors

Abstract

In this report, ZnWO₄ nanowall arrays (NWAs) were grown on Ni foam by a hydrothermal route and investigated for application in supercapacitors for the first time. The resulting NWAs were analyzed by using X-ray diffraction spectroscopy, scanning electron microscopy, and transmission electron microscopy. ZnWO₄ NWAs exhibited high electrochemical property with a specific capacitance of 2.5 F cm⁻² at a charge and discharge current density of 20 mA cm⁻² (1250 F g⁻¹ at current density of 10 A g⁻¹). Furthermore, they showed an excellent cycling ability at different current densities up to 100 mA cm⁻², and 92% (2.3 F cm⁻²) of the initial capacitance remained after 4000 cycles. The open network structure consisting of interconnected ZnWO₄ NWAs directly grown on current collectors is advantageous for electron transport and electrolyte diffusion which can facilitate the electrochemical reaction. Our work not only demonstrated a facile hydrothermal method for ZnWO₄ NWAs directly grown on Ni foam, but also revealed ZnWO₄ to be a promising electrode for high-property supercapacitors.