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.
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