Density functional theory study on the electrocatalytic performance of defected monolayer vanadium diselenide for oxygen evolution and reduction reactions

The slow oxygen evolution reaction (OER) in the water-splitting driven by electricity, significantly impedes the hydrogen evolution reaction (HER). In this paper, density functional theory with D3 correction (DFT-D3) is utilized to explore the electrocatalytic potential of defected mono-layered VSe₂ for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Intrinsic point defects, such as, selenium (D1) and vanadium (D2) vacancies, are introduced into 2D-VSe₂. Possible sites, like, Se Top, V Top, vacancies and bridge positions are investigated for OER and ORR intermediates (O, OH and OOH). VSe₂ monolayer with V vacancy (D2) shows significantly reduced overpotential for OER/ORR (η= 0.19 V/0.46 V), indicating enhanced catalytic activity. The OER performances of VSe₂ monolayer with V vacancy (D2) (η= 0.19 V) surpasses those of IrO₂ and RuO₂ (η= 0.37 V and 0.56 V), and the ORR performances (η= 0.46 V) are comparable to those of precious Pt (η=0.4 V). The Pourbaix diagram further confirms the aqueous stability of VSe₂ in various pH environments, establishing its potential as a robust catalyst for OER and ORR. These findings suggest that defect engineering, particularly vanadium vacancies, could significantly improve the electrocatalytic activity of VSe₂ monolayers, contributing to the development of high-performance electrocatalysts.