Mo/Co doped 1T-VS2 nanostructures as a superior bifunctional electrocatalyst for overall water splitting in alkaline media

Abstract

Electrocatalytic water splitting in alkaline media is greatly challenged by the lack of highly active bifunctional electrocatalysts to overcome the sluggish kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. In this regard, transition metal dichalcogenides (TMDs) have emerged as potential bifunctional catalysts for overall water splitting, but still suffer from high overpotentials. Herein, we report Mo and Co doped nanostructured 1T-VS₂ directly grown on carbon cloth in a one step hydrothermal reaction as a binder free highly active bifunctional electrocatalyst for the HER and OER in alkaline media. The bifunctional electrocatalytic properties are tuned by optimizing the doping concentration of the heteroatoms. Various physicochemical results demonstrate that 10% molar doping of Mo and Co in VS₂ (10:MoCo-VS₂) leads to the highest bifunctional activities demanding HER and OER overpotentials of only 63 and 248 mV at a current density of 10 mA cm⁻². Furthermore, a 10:MoCo-VS₂ based electrolyzer fabricated using 10:MoCo-VS₂ as both the anode and cathode also demonstrated high overall water splitting activity demanding a low cell potential of only 1.54 V to generate a current density of 10 mA cm⁻² with long-term stability (35 h), which are attributed to its ultrathin and mesoporous nature, expanded interlayer spacing (∼63%), activated basal planes, and abundant active sites resulting from the synergistic effect of optimized Mo and Co dual doping into the 1T-VS₂ host material. This study thus presents a facile approach for designing efficient bifunctional electrocatalysts based on heteroatoms doped VS₂ for electrocatalytic water splitting in alkaline media.