Theoretical Investigations On The New And Nonprecious HER Catalysts Based On The Layered SnP₃ Nanosystems And The Correlative Catalytic Mechanisms

Fossil energy is an important material basis for human survival and development.However,resource constraint and environmental deterioration have prompted us to seek and develop affordable,reliable and clean energy sources.Hydrogen is considered as an ideal energy carrier to replace exhaustible fossil fuels,due to its virtues of abundance,environmental friendliness and high gravimetric energy density.The core challenge is to achieve highly efficient catalysts to minimize the necessary overpotential during the electrocatalytic hydrogen evolution reaction.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 serves as the most active site.Comparatively,few-layered SnP₃ nanostructures can possess relatively weak HER activity.Furthermore,we propose an effective approach through applying surface strain to further improve the HER activity of these 2D layered SnP₃ nanostructures.The computed results reveal that application of compressive strain on monolayer 1L-SnP₃and 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?G_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.It should be noted that our computed results reveal that all these 2D layered SnP₃-based nanomaterials can uniformly exhibit considerably large negative interlayer interaction energies(E_int),indicating their higher structural stabilities.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.