Unravelling the Electro‐Photocatalytic Water Splitting Capabilities of 2D‐Bifunctional Mo ₂ S ₃ ‐WS ₂ Catalyst: Implications for Renewable Energy Platforms

Addressing the energy crisis and environmental pollution demands the development of efficient electro- and photocatalysts capable of facilitating hydrogen production via water splitting. Engineering semiconductor-based 2D heterostructures with remarkable visible-light harvesting capability proves to be an effective approach for constructing profoundly active electro-photocatalytic entities. This paper focuses on designing a heterostructure comprising tungsten disulphide (WS₂) integrated with molybdenum sesquisulfide (Mo₂S₃) to increase electrocatalytic activity. Moreover, nanoengineering the 2D/2D heterostructure with varying lateral dimensions increases the density of catalytic active sites. Due to its superior geometric configuration, the polarization curves of the Mo₂S₃-WS₂ composite display outstanding characteristics as a bifunctional electro-photocatalyst, with low overpotentials (η) of 92 mV for hydrogen evolution reaction (HER) and 310 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm², maintaining stability for up to 100 h. The electrolyzer achieved a current density of 1 A cm² with a cell voltage of 2.07 V, corresponding to a voltage efficiency of 72%. Integrating the electrolyzer with a commercial silicon solar cell enabled efficient solar-driven water splitting, reaching a current density of ≈0.8 A cm² at an applied voltage of 2 V. This work provides valuable insights into the design of innovative hetero-nanostructures with superior catalytic properties for water splitting, contributing to a sustainable energy future.