Anchoring carbon layers and oxygen vacancies endow WO3-x/C electrode with high specific capacity and rate performance for supercapacitors

Herein, novel hierarchical carbon layer-anchored WO3-x/C ultra-long nanowires were developed via a facile solvent-thermal treatment and a subsequent rapid carbonization process. The inner anchored carbon layers and abundant oxygen vacancies endowed the WO3-x/C nanowire electrode with high conductivity, as measured with a single nanowire, which greatly enhanced the redox reaction active sites and rate performance. Surprisingly, the WO3-x/C electrode exhibited outstanding specific capacitance of 1032.16 F g(-1) at the current density of 1 A g(-1) in a 2 M H2SO4 electrolyte and maintained the specific capacitance of 660 F g(-1) when the current density increased to 50 A g(-1). Significantly, the constructed WO3-x/C//WO3-x/C symmetric supercapacitors achieved specific capacitance of 243.84 F g(-1) at the current density of 0.5 A g(-1) and maintained the capacitance retention of 94.29% after 5000 charging/discharging cycles at the current density of 4 A g(-1). These excellent electrochemical performances resulted from the fascinating structure of the WO3-x/C nanowires, showing a great potential for future energy storage applications.