Hydrogen Evolution Reaction on BP Monolayer and MoS₂/BP van der Waals Heterostructure from First-principles

Molecular hydrogen is a sustainable energy carrier. One of the methods for its production is water splitting, whereby electrochemical hydrogen evolution reaction (HER) is efficiently catalyzed by Pt. Owing to its high cost, this field is being actively explored for earth-abundant low-cost electrocatalysts like MoS₂. MoS₂ is a promising acid-stable catalyst; however, its applicability is limited by poor electrical transport and inefficient charge transfer at the interface. Therefore, the present work examines its bilayer van der Waals heterostructure (vdW HTS), which incorporates spatial separation of e^--h⁺ on two layers. As per existing literature, the second constituent monolayer BP is advantageous as an electrode material, owing to its chemical stability in both oxygen and water environments. We have performed first-principles based calculations under the framework of density functional theory (DFT) for hydrogen evolution reaction in an electrochemical double layer on the BP monolayer and MoS₂/BP vdW HTS. The climbing image nudged elastic band method have been employed to determine the minimum energy pathways. The comparative study has been undertaken by analyzing their electrostatic potential and work function in Heyrovsky and Tafel reaction intermediates. Finally, we observe the Heyrovsky reaction path to be favorable.