二维金属-六亚氨基苯框架材料的气体吸附效应  

Effects of Gas Adsorption on Two Dimensional Metal-hexaiminobenzene Frameworks

作　　者：孙国栋 王雪 江国亮 徐之勇 刘洪梅 SUN Guodong;WANG Xue;JIANG Guoliang;XU Zhiyong;LIU Hongmei(Institute of Condensed Matter Physics, School of Physics and Electronic Engineering, Linyi University, Linyi 276000, China;Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003, China)

机构地区：[1]临沂大学物理与电子工程学院凝聚态物理研究所,临沂276000 [2]河南科技学院化学化工学院,新乡453003

出　　处：《高等学校化学学报》2019年第5期995-1004,共10页Chemical Journal of Chinese Universities

基　　金：山东省自然科学基金(批准号:ZR2017QA003);山东省大学生科学研究项目(批准号:18SSR060)资助~~

摘　　要：利用密度泛函理论研究了气体分子(NH3,H_2O,H_2S,NO2)吸附在二维M3(HIB)2(M=Ni,Cu; HIB为六亚氨基苯)薄膜上体系的几何结构和电子结构的变化.结果表明,2种薄膜对气体分子的响应不同.其中NH3,H_2O和H_2S在M3(HIB)2薄膜表面的吸附较弱,主要与薄膜的亚氨基形成氢键,吸附能均小于-0. 36e V,吸附对体系电子性质的影响很小.但是NO2分子在薄膜表面形成化学吸附,吸附能在-0. 65～-1. 72 e V范围内.吸附NO2分子使其电子结构发生明显改变,如Cu_3(HIB)_2在费米能级处打开带隙,由金属性质转变为半导体性质.这是由于NO2分子的pz轨道与金属原子dz2轨道发生了强烈的轨道杂化.此外,研究发现高浓度的NO2分子吸附能够使Ni3(HIB)2薄膜由非磁性变为磁性体系,由普通金属性质变为半金属性质;而高浓度的NO2分子使Cu_3(HIB)_2薄膜由金属性质变为半导体性质,薄膜电导率降低.The effects of gas molecules(NH3,H2O, H2S, and NO2) adsorption on two-dimensional M3(HIB)2(M=Ni,Cu;HIB =hexaiminobenzene) surfaces on the geometric structure and electronic structure were studied via the first-principles theory. The results show that there are different responses of two thin films to four gas molecules. The adsorptions of NH3,H2O and H2S on the surface of M3(HIB)2 thin films are weak and the gas molecules tend to form hydrogen bond with the imino group of the film with an adsorption energy that is less than-0. 36 eV. These weak adsorptions just slightly affect the electronic properties of the adsorbed films. In contrast,NO2 molecules are strongly chemisorbed on the two films with adsorption energy in the region of-0. 65--1. 72 eV. The adsorption of NO2 molecules evidently changes the electronic structures of the film. For instance,there is a band gap opening at the Fermi level for Cu3(HIB)2 film and it changes from metal to semiconductor. This feature originates from the strong orbital hybridization between NO2 pzand metal dz2 orbitals. Furthermore,when NO2 molecules with a high concentration are adsorbed on M3(HIB)2 surface,the Ni3(HIB)2 film transits from nonmagnetic to magnetic states and changes from metallic to half-metallic property, while the Cu3(HIB)2 film converts to semiconductor, suggesting a potential application of M3(HIB)2 films in gas sensing.

关 键 词：金属有机框架材料 表面吸附 电子结构 半金属 

分 类 号：O647[理学—物理化学]