二硫化钼/石墨烯异质结的界面结合作用及其对带边电位影响的理论研究  

Interfacial cohesive interaction and band modulation of two-dimensional MoS_2/graphene heterostructure

作　　者：危阳[1] 马新国[1,2] 祝林[1] 贺华[1,2] 黄楚云[1,2] 

机构地区：[1]湖北工业大学理学院,武汉430068 [2]湖北工业大学太阳能高效利用湖北省协同创新中心,武汉430068

出　　处：《物理学报》2017年第8期267-276,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51472081);湖北工业大学高层次人才启动基金(批准号:GCRC13014);绿色工业引领计划(批准号:YXQN2016005);湖北省协同创新中心开放基金(批准号:HBSKFZD2015004)资助的课题~~

摘　　要：采用基于色散修正的平面波超软赝势方法研究了二硫化钼/石墨烯异质结的界面结合作用及其对电荷分布和带边电位的影响.研究表明二硫化钼与石墨烯之间可以形成范德瓦耳斯力结合的稳定堆叠结构.通过能带结构计算,发现二硫化钼与石墨烯的耦合导致二硫化钼成为n型半导体,石墨烯转变成小带隙的p型体系.并通过电子密度差分图证实了界面内二硫化钼附近聚集负电荷,石墨烯附近聚集正电荷,界面内形成的内建电场可以抑制光生电子-空穴对的复合.石墨烯的引入可以调制二硫化钼的能带,使其导带底上移至-0.31 eV,提高了光生电子还原能力,有利于光催化还原反应.To improve the efficiency of water-splitting,a key way is to select suitable semiconductor or design semiconductor based heterostructure to enhance charge separation of photogenerated h-＋-e--pairs.It is possible for a two-dimensional（2D） heterostructure to show more efficient charge separation and transfer in a short transport time and distance.Among numerous heteromaterials,the 2D layered MoS_2 has become a very valuable material in photocatalysis-driven field due to the appropriate electronic structure,peculiar thermal and chemical stability,and low-cost preparation.To couple with MoS_2,layered graphene will be an ideal candidate due to extremely high carrier mobility,large surface area,and good lattice match with MoS_2.At present,a lot of researches focus on the synthesis and modification of MoS_2/graphene heterostructure.However,it is hard to detect directly the weak interaction between MoS_2 and graphene through the experiment.Here,an effective structural coupling approach is described to modify the photoelectrochemical properties of MoS_2 sheet by using the stacking interaction with graphene,and the corresponding effects of interface cohesive interaction on the charge redistribution and the band edge of MoS_2/graphene heterostructure are investigated by using the planewave ultrasoft pseudopotentials in detail.Three dispersion corrections take into account the weak interactions between MoS_2 and graphene,resulting in an equilibrium layer distance d of about 0.34 nm for the MoS_2/graphene heterostructure.The results indicate that the lattice mismatch between monolayer MoS_2 and graphene is low in contact and a van der Waals interaction forms in interface.Further,it is identified by analyzing the energy band structures and the threedimensional charge density difference that in the MoS_2 layer in interface there appears an obvious electron accumulation,which presents a new n-type semiconductor for MoS_2 and a p-type graphene with a small band gap（ 〈0.1 eV）.In addition,Mo 4d electrons in the upper va

关 键 词：异质结光催化 二硫化钼 能带调制 第一性原理 

分 类 号：O643.36[理学—物理化学]