金红石相TiO_2(110)面吸附H_2S分子光学气敏效应的微观机制与特性  

Microscopic Mechanism and Characteristics of Optical Gas Sensing Material Rutile Titanium Dioxide(110)Surface Adsorption H_2S Molecules

作　　者：朱洪强[1] 冯庆[1] 岳远霞[1] 周晴[1] 

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

出　　处：《中国激光》2014年第12期148-155,共8页Chinese Journal of Lasers

基　　金：国家自然科学基金(61274128;61106129);重庆市自然科学基金(CSTC2013JCYJA0731);重庆市科委项目(CSTC2014JCYJA0219)

摘　　要：光学气敏材料吸附气体分子后导致光学性质发生变化,运用这一原理来检测环境中的气体成分,称为光学气敏效应。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,研究了光学气敏材料金红石相TiO2（110）表面吸附H2S分子的微观特性,计算了TiO2（110）表面吸附能、电荷密度、态密度和光学性质的变化。结果表明,TiO2最稳定的表面是终止于二配位O原子的（110）面,只有含有氧空位的表面才能稳定吸附H2S,且氧空位比例越高,越有助于H2S吸附于表面;表面吸附H2S以水平吸附方式为主,在氧空位比例达到33%时,吸附能为0.7985eV;吸附的实质是表面氧空位具有氧化性,氧化了H2S分子。在可见光400-760nm范围内,存在氧空位的TiO2（110）表面吸附H2S后都可改善表面的光学性质。氧空位缺陷浓度越高,改善材料对可见光的吸收和反射能力越强,光学气敏响应能力越佳。Optical gas sensor material adsorption gas molecules lead to changes in optical properties to detect environmental gas composition, which is called optical gas sensing effect. Microscopic characteristics of rutile titanium dioxide （110） surface adsorption H2 S molecules are studied, under the first-principles plance-wave ultrasoft pseudopotential method based on density functional theory （DFT） system, and adsorption energy, charge density, density of states and optical properties of TiO2 （llO） surface are calculated. The results show that, the most stable surface is TiO2 （110） surface which terminated on the two coordinated O atoms; only containing oxygen vacancy surface can stably adsorb H2S molecules; the higher of the oxygen vacancy concentration, the higher adsorption energy; the main way of surface adsorption HzS molecules is horizontal adsorption. When oxygen vacancy concentration reach 33%, adsorption energy is 0. 7985 eV. The adsorption essence is surface oxygen vacancies oxidation H2S molecule. In the visible light range of 400- 760 nm, the surface optical properties can be improved only when H2 S molecules adsorption on containing oxygen vacancies surface, moreover, the higher concentration of oxygen vacancy, the more obvious improvement of absorption, reflection ability and optical gas sensing performance.

关 键 词：原子与分子物理学 光学气敏材料 金红石 H2S 密度泛函理论 

分 类 号：O469[理学—凝聚态物理]