Surface oxidation for enhancing the hydrogen evolution reaction of metal nitrides: a theoretical study on vanadium nitride

Abstract

The rational design of novel catalysts for energy applications has been an area of immense interest over the past decades. Recent studies have demonstrated that slight surface oxidation of nitrides can boost their catalytic activity, especially towards hydrogen adsorption. In this study, we have considered VN as a simple model nitride to simulate H adsorption on pure and oxygen polluted surfaces. First, we have evaluated the physical characteristics and stability of various facets. Diversity in the VN catalytic activity can originate from a variety of surface characteristics. Our calculations reveal the (112) and (200) surfaces as the most stable ones, while the (101), (111), and (113) surfaces are roughly in the same range of energy. The facet-dependent activity of VN toward H adsorption is then carefully discussed. A low level of oxygen contamination appears to make the VN hydrogen adsorption robust and beyond that, a thin oxide surface layer can act as an activation layer, playing a positive role in improving the catalytic performance. We anticipate this picture to be an important input for designing enhanced nitride-based catalysts with controlled oxidation of surfaces.