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 kWkg−1. Notably, the device exhibits the capacity retention of 86.8% after 7000 charge/discharge cycles, demonstrating a high stability of the VS2 electrode.
Highlights
Demand on renewable energy is growing impressively day-by-day
Transition metal dichalcogenides (TMDs) [6], metal phosphides [7], MXenes [8] and MOFs [9,10] have been explored as suitable alternatives of Pt for the hydrogen evolution reaction (HER)
VS2-3tobased electrode obtained from the ethylene glyA solvo-/hydro-thermal employed design a solution-phase mediated col and water mixed solvent-mediated synthesis route demonstrated a high catalytic perlayered VS2 microflower structured materials in a mixture of ethylene glycol and water formance for HER in both acidic and alkaline electrolytes containing 0.5 M H2SO4 or 1 M
Summary
Demand on renewable energy is growing impressively day-by-day. The heavy reliance on fossil fuels to fulfill the global energy demand has resulted many environmental issues [1]. Green and efficient energy resources for sustainable energy conversion and storage technologies are highly demandable. Hydrogen (H2 ) is a green energy that may be produced by water-electrolysis. Water electrolysis is commonly catalyzed by noble metal-based catalysts such as those consisting of platinum (Pt) and iridium (Ir). These noble metals are rare and are very expensive, resulting the water-electrolysis unaffordable commercially [4,5]. Non-noble metal-based compounds such as MoS2 , WS2 , CoS2 , NiSe2 , CoSe2 [11], amorphous MoSx, VS2 , CoP, Ni2 P, FeP, WP, MoP|S, CoPS, NiP1.93 Se0.07 , and NiMo alloys have been studied as potential
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