Increasing Silicon Concentration and Doping Heteroatom to Successfully Realize High HER Catalytic Activity in 2D Metal-Free BSi n (n = 1–4) Structures: A First-Principles Study

Abstract

Under the DFT calculations, the graphene-like two-dimensional (2D) BSi n (n = 1–4) nanostructures are stable in terms of energy, kinetics and thermal aspects, and can possess metallic conductivity, which are advantageous to their catalytic activities for hydrogen evolution reaction (HER). Our computed results reveal that they can uniformly exhibit high HER catalytic activity. With increasing the Si/B atomic ratio, higher HER activity can be achieved, due to the change from weak aromaticity to strong anti-aromaticity for the correlative BxSiy six-membered rings. Moreover, by doping P, S, Ge and C atoms with the different electronegativity, the HER activity of the studied systems can be further improved because the electron transfer induced by these dopants can effectively activates the relevant B and Si atoms. In addition, in view of more active sites, increasing the Si concentration can also generally increase the HER activity of doped systems. For all BSi n systems studied, the Si–Si bridge sites or Si-sites can uniformly serve as the most active sites. This study not only represents the first application of 2D metal-free BSi n in HER catalysis, but also provides new strategies for designing high-efficient and low-cost HER electrocatalysts based on Si/B or even other Si-containing materials.