SP^3杂化的气体分子在金红石相二氧化钛(110)面吸附规律与特性  

A study on adsorption law and characteristics of SP^3 hybrid gas molecules in the rutile titanium dioxide(110) surface

作　　者：朱洪强[1,2] 冯庆[1,2] 周晴[1,2] 陈小雨[1,2] 

机构地区：[1]重庆师范大学物理与电子工程学院,重庆401331 [2]重庆市光电功能材料重点实验室,重庆401331

出　　处：《中国科学：物理学、力学、天文学》2015年第7期100-108,共9页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(批准号:61274128);重庆市自然科学基金(编号:CSTC2013JCYJA0731);重庆市科委项目(编号:CSTC2014-JCYJA0219)资助项目

摘　　要：采用基于密度泛函理论(DFT)体系下的第一性原理平面波超软赝势方法,研究了sp3杂化气体分子H2O,NH3和CH4在金红石相Ti O2(110)表面的吸附.研究发现:含有氧空位的表面较无氧空位表面更容易吸附气体分子.影响吸附稳定性和吸附能的主要因素是分子的极化率,分子极化率越大,吸附越稳定.表面氧空位对分子负电荷中心的吸附是整个吸附的主要原因.通过差分电荷密度和电荷布居数分析来看,表面与吸附分子存在电荷转移,转移电子数目大小为:N>O>C,吸附方式为化学吸附,吸附稳定性为NH3>H2O>CH4.通过态密度、吸收谱和反射谱分析发现,表面氧空位缺陷使材料在费米能级附近出现了态密度峰值,极大地改变了材料的光学性质,占主导作用;而表面吸附H2O,NH3,CH4分子后对表面的光学性质影响相对较低,占辅助作用.O,N,C原子的电子在费米能级附近的态密度贡献为N>O>C,与转移电子数目顺序一致.相比氧空位表面,吸附CH4后对材料的光学性质影响不大,但吸附H2O和NH3后其吸收系数和反射率有所降低.这为进一步研究该材料的气敏传感特性提供了理论基础.This paper studied rutile titanium dioxide （110） surface adsorption sp3 hybrid gas molecules such as 1-I20, NH3 and CH4 by using the first-principles plane-wave ultrasoft pseudopotential method based on density functional theory （DFT）. The results showed that： comparing to the surface without oxygen vacancy, the surface containing oxygen vacancy more easily adsorbed gas molecules. The main factor affecting the adsorption stability and adsorption energy is polarizability of molecular. The main adsorption reason is surface oxygen vacancies adsorbing the negative charged center. From analysis of the difference charge density and charge population, charge transfer exists in surface and molecular and the order of transfer number is N〉O〉C. The adsorption method is chemical adsorption and adsorption stability is NH3〉H20〉CH4. From analysis of density of states, absorption spectrum and reflectance spectrum, surface oxygen vacancy defects caused a peak in density of states near the Fermi level, greatly changed the optical properties of the material, which played the dominant role, while after the surface adsorption H20, NH3 and CH4 molecules had less influence on surface optical properties, which played the auxiliary role. The electrons of O, N, C atoms contribution to density of states near the Fermi energy is N〉O〉C, which is the same order of the electron transfer number. Compared to the surface oxygen vacancies, there is little effect on the optical properties of materials after adsorption of CH4, and the absorption coefficient and reflectance decreased after adsorption of H2O and NH3. This study provides the theoretical foundation for the further study of the characteristics of gas sensing materials.

关 键 词：sp3杂化 密度泛函理论 DFT-D TIO2 表面吸附 

分 类 号：O647.3[理学—物理化学]