A Facile Design of Solution-Phase Based VS2 Multifunctional Electrode for Green Energy Harvesting and Storage

Abstract

This work reports the fabrication of vanadium sulfide (VS2) microflower via one-step solvo-/hydro-thermal process. The impact of ethylene glycol on the VS2 morphology and crystal structure as well as the ensuing influences on electrocatalytic hydrogen evolution reaction (HER) and supercapacitor performance are explored and compared with those of the VS2 obtained from the standard pure-aqueous and pure-ethylene glycol solvents. The optimized VS2 obtained from the ethylene glycol and water mixed solvents exhibits a highly ordered unique assembly of petals resulting a highly open microflower structure. The electrode based on the optimized VS2 and exhibits a promising HER electrocatalysis in 0.5 M H2SO4 and 1 M KOH electrolytes, attaining a low overpotential of 161 and 197 mV, respectively, at 10 mA.cm(-2) with a small Tafel slope 83 and 139 mVdec 1. In addition, the optimized VS2 based electrode exhibits an excellent electrochemical durability over 13 h. Furthermore, the superior VS2 electrode based symmetric supercapacitor delivers a specific capacitance of 139 Fg(-1) at a discharging current density of 0.7 Ag-1 and exhibits an enhanced energy density of 15.63 Whkg(-1) at a power density 0.304 kWk g(-1). Notably, the device exhibits the capacity retention of 86.8% after 7000 charge/discharge cycles, demonstrating a high stability of the VS2 electrode.