| Two-dimensional materials have attracted widespread attention in the past few decades due to their unique electronic structures,chemical reactivity,and mechanical properties.Among them,the most famous representative is graphene,which has high electron mobility,optical transparency,and mechanical strength,providing ample opportunities for its application in various fields.Monolayer Boron Phosphide（BP）,as a close relative of graphene,possesses a direct bandgap and extremely high carrier mobility,making it another promising two-dimensional material.This article aims to explore the application of BP and its derived heterostructures in photocatalytic water splitting.We demonstrate through first-principles theory that BP and its heterostructures have significant competitive advantages in the field of photocatalysis.The main research contents are as follows:Firstly,based on first-principles calculations,we investigate the geometric structure,electrical and optical properties of BP.The results show that the single layer BP is a direct band gap semiconductor with a band gap of 1.35 e V.It is noteworthy that this two-dimensional material has extremely high electron mobility～8.46×104 cm2V-1s-1and large gap between hole and electron mobility,which can effectively hinder photogenerated electron and hole recombination.In the pH 3-4 range,the band edge location of monolayer BP is favorable for water decomposition.However,under the control of+6%tensile strain,the band gap of single layer BP is greatly increased,and the pH application range of photocatalysis is increased to 1-6,which can almost cover the whole acidic environment.In addition,the light absorption spectrum also shows its important light absorption capacity in the ultraviolet and visible regions.These studies show that 2D BP is a promising photocatalytic material.Secondly,the photocatalytic properties of BP/MoSeO vertical heterostructures with two different configurations were studied.The results show that both heterostructures have type Ⅱ band structure and generate internal electric fields to separate photogenerated electron-hole pairs,but their band edge types are different.O-Mo-Se/BP（Se atom near BP）is a typical type Ⅱ heterostructure,and Se-Mo-O/BP（O atom near BP）is a direct Z-scheme heterostructure.Although both have small band gap values,the direct Z-scheme heterostructure Se-Mo-O/BP has the ability to oxidize reducing water.In addition,the light absorption capacity of the direct Z-scheme heterostructure is further enhanced on the basis of BP,and the light absorption range is also enlarged due to the decrease of the band gap.This study provides a reference for the design and synthesis of efficient photocatalysts and a new idea for the realization of renewable energy technologies such as hydrogen production by water decomposition.Finally,the photocatalytic properties of two-dimensional BP/BN lateral heterostructures were investigated,with armchair configuration and zigzag configuration as the contact boundary of heterostructures respectively.The results show that BP can increase the band gap and improve the photocatalytic water decomposition ability through the heterojunction formed by BN with insulating properties.However,the band gap of these two configurations also decreases with the increase of the width of the heterostructure.In addition,the electrons and holes of the two two-dimensional BP/BN lateral heterostructures are mainly distributed in two different materials,which further proves that the lateral heterostructures can also inhibit the photogenerated carrier recombination and allow the REDOX reaction of water to realize spatial separation,thus improving the photocatalytic ability.Therefore,two-dimensional BP/BN lateral heterostructures also have great application prospects in the field of photocatalysis. |
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