Applying surface strain and coupling with pure or N/B-doped graphene to successfully achieve high HER catalytic activity in 2D layered SnP3-based nanomaterials: a first-principles investigation

Abstract

Based on DFT computations, we have systematically investigated the catalytic activity for the hydrogen evolution reaction (HER) on two-dimensional (2D) layered SnP₃-based systems. It is found that the monolayer SnP₃ nanostructure can exhibit good HER activity, where the P atom with a near-zero ΔG_H* value serves as the most active site. Comparatively, few-layered SnP₃ nanostructures can possess relatively weak HER activity. Furthermore, application of compressive strain on monolayer 1L-SnP₃ and tensile strain on few-layered nL-SnP₃ (n ≥ 2) systems can endow all these 2D layered nanostructures with higher HER activity, by optimizing the adsorption state of H* and conductivity simultaneously. Moreover, a series of new 2D bilayer and sandwich nanostructures nL-SnP₃/G have been constructed by alternately stacking the monolayer SnP₃ and graphene. Regardless of the layer number, all of them can uniformly exhibit higher HER catalytic activity than the monolayer, in view of the optimized ΔG_H* values and good conductivity. The HER catalytic activities of these 2D composite systems can be further enhanced by doping N or B atoms into the graphene subunit, with B-doping being superior to N-doping. In addition, all the correlative catalytic mechanisms are also analyzed in detail. Clearly, coupling with the high structural stability and good conductivity, all these 2D layered SnP₃-based nanomaterials can be very promising candidates as highly efficient and nonprecious HER electrocatalysts.