Cu-X(X=C,Si,Ge,Sn,Pb)掺杂对闪锌矿ZnS可见光吸收的影响研究

Effects of Cu-X(X=C,Si,Ge,Sn,Pb)doping on visible light absorption of ZnS

闪锌矿ZnS是一种常见的光触媒,是催化水制氢原料。闪锌矿ZnS的带隙较宽(3.68 eV),这在一定程度上制约了闪锌矿ZnS对可见光的吸收。为了增加闪锌矿ZnS对可见光的吸收效率,拓宽其工程应用范围,文章基于第一性原理分析了Cu-X(X=C,Si,Ge,Sn,Pb)掺杂对闪锌矿ZnS的稳定性、光学吸收特性以及催化特性的影响。分析结果表明:Cu-X(X=C,Si,Ge,Sn,Pb)掺杂闪锌矿ZnS的结合能分别为-2.33,-2.21,-2.18,-2.06,-1.93 eV,因此,掺杂后的结构比较稳定;Cu-X(X=C,Si,Ge,Sn)掺杂闪锌矿ZnS后,闪锌矿ZnS的带隙宽度分别由3.68 eV减小至3.12,2.85,2.63,2.32 eV,并且能够在禁带中引入了p-d杂化能级,这有利于可见光的吸收;Cu-X(X=C,Si,Ge,Sn,Pb)掺杂闪锌矿ZnS后,闪锌矿ZnS导带边位置分别为-1.03,-0.93,-0.905,-0.865,-0.79 eV,闪锌矿ZnS价带边位置分别为2.29,2.19,1.945,1.765,1.53 eV,上述导、价带边位置均满足光水解制氢条件。

ZnS is a kind of photocatalyst which can be used to splitting water to produce hydrogen.However,due to the wide bandgap(3.68 eV),the absorption of visible light by ZnS is restricted to a certain extent.The effects of Cu-X(X=C,Si,Ge,Sn,Pb)doping on the stability,optical absorption coefficient and catalytic properties of zinc sphalerite ZnS were studied by first principles.The results show that the binding energies of Cu and X(X=C,Si,Ge,Sn,Pb)doped ZnS are-1.84,-2.33,-2.21,-2.18,-2.06,-1.93 eV,respectively.The binding energies are negative,so the doped structure is stable.Cu-X(X=C,Si,Ge,Sn)co-doping reduces the band gap of ZnS from 3.68,3.12,2.85,2.63,2.32 eV respectively.In the meanwhile,p-d hybrid level is introduced into the forbidden band,which is beneficial to visible light absorption.The decrease of band gap results in red shift of absorption coefficient.The conduction band edge positions of Cu-X doped ZnS are-1.03,-0.93,-0.905,-0.865,-0.79 eV,respectively,while the valence band edge positions are 2.29,2.19,1.945,1.765,1.53 eV,respectively,which met the conditions of splitting water.