Solvent modulated self-assembled VS2 layered microstructure for electrocatalytic water and urea decomposition

Abstract

Urea oxidation reaction (UOR) assisted water-splitting is a promising approach for effective treatment of urea-rich waste-water at the anode and parallelly generate green-hydrogen (H-2) energy at the cathode via hydrogen evolution reaction (HER). However, facile designing and fabricating robust and cheap electrodes derived from earth-abundant materials is a great challenge. This work reports the synthesis of vanadium sulfide (VS2) micro-flowered structure via solvent-assisted hydrothermal method using ethylene glycol as an additive in the aqueous-based reaction medium, which has imparted a significant effect on the morphology and the crystallinity of the VS2. In addition, in contrast to the VS2 electrode fabricated in a pure aqueous medium, the ethylene glycol mediated VS2 electrode upon coupling as a cathode and anode in an HER||UOR vs reversible hydrogen electrode (RHE)-based three-electrode configuration demonstrates a significantly reduced overall urea decomposition potential of 1.38 V at a current density of 10 mA cm(-2) as compared to the conventional water-splitting of 1.75 V vs RHE. The obtained high-performance electrocatalytic activity on UOR and HER can be ascribed to the influence of ethylene glycol solvent, particularly on VS2 growth, morphology, and crystallinity, favoring the formation of abundant catalytic sites with facile electrolyte diffusion and electrolysis.