Single atom functionalization in vanadium dichalcogenide monolayers: towards enhanced electrocatalytic activity

Abstract

Our work focused on the first-principles study of comparative analysis for the enhancement of hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) activities of two dimensional (2D) pristine vanadium dichalcogenide (VS₂, VSe₂, and VTe₂) layered structures. Additionally, this work also included the effect of non-metal (carbon, nitrogen and phosphorus) functionalization on the catalytic activities of these 2D layers. In this proposed work, the adsorption of different intermediates, i.e., HER intermediate (H*), OER intermediates (O*, OH*, and OOH*), and ORR intermediates (OOH*, OH*, and O*) on the different possible favored sites of pristine and functionalized VS₂, VSe₂, and VTe₂ monolayers have been investigated for all pristine and functionalized cases. We have investigated the optimized structures, defect formation energies, projected density of states (PDOS), work functions (ϕ), and the reaction coordinates based on the adsorption free energies (ΔG) for all pristine and functionalized monolayers. Among all pristine monolayers, the pristine VS₂ monolayer was found as the most active HER and OER catalyst, whereas for functionalized cases, the C-doped VS₂ monolayer appeared as the best candidate for the HER mechanism from the adsorption free energy based reaction coordinate perspective. In addition, our reaction coordinate mapping for the OER and ORR mechanism reflects the emergence of pristine VS₂ and C-doped VSe₂ monolayers as promising electrocatalysts. This proposed research work would offer new 2D materials as efficient and less expensive electrocatalysts.