二维Ⅲ族硫化物Janus多层结构的高效光解水特性:内建电场和空位缺陷效应（英文）

Highly-efficient overall water splitting in 2D Janus group-Ⅲ chalcogenide multilayers: the roles of intrinsic electric filed and vacancy defects

二维范德华材料被广泛用作光分解水催化剂,但其直接的能量转化效率有待提高.因此,寻找具有高效光解水催化特性的二维材料成为理论和实验研究的热点.本文从量子力学第一性原理出发,预言了一类具有高效光解水特性的光催化剂:二维Ⅲ族硫化物Janus多层结构InGaXY,M2XY和InGaX2(M=In/Ga;X,Y=S/Se/Te).理论计算表明,多层材料的内建电场不仅可以促进光生载流子的空间分离,而且可以有效地调控材料能带的位置,提高能量转化效率.Janus多层材料能量转化效率的理论上限可以达到38.5%,接近了理论极限值(47%).更重要的是,在InGaSSe双层引入Ga空位可以有效降低析氢和析氧反应的过电势,仅仅依靠光生载流子提供的电压就可以驱动光解水催化反应.该理论结果不仅预言了二维Ⅲ族硫化物Janus多层材料可以作为高效的光解水催化材料,而且为设计和寻找高效光催化材料提供了新思路.

Two-dimensional(2 D)van der Waals materials have been widely adopted as photocatalysts for water splitting,but the energy conversion efficiency remains low.On the basis of first-principles calculations,we demonstrate that the 2 D Janus group-Ⅲchalcogenide multilayers:In Ga XY,M2XY and In GaX2(M=In/Ga;X,Y=S/Se/Te),are promising photocatalysts for highly-efficient overall water splitting.The intrinsic electric field enhances the spatial separations of photogenerated carriers and alters the band alignment,which is more pronounced compared with the Janus monolayers.High solar-to-hydrogen(STH)efficiency with the upper limit of 38.5%was predicted in the Janus multilayers.More excitingly,the Ga vacancy of In Ga SSe bilayer effectively lowers the overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)to the levels provided solely by the photogenerated carriers.Our theoretical results suggest that the 2 D Janus group-III chalcogenide multilayers could be utilized as highly efficient photocatalysts for overall water splitting without the needs of sacrificial reagents.