United States Department of Energy, National Energy Technology Laboratory, Pittsburgh, Pennsylvania 15236, USA.
J Chem Phys. 2011 Sep 28;135(12):124701. doi: 10.1063/1.3638181.
Adsorption, diffusion, and dissociation of CO(2) on the anatase (101) surface were investigated using dispersion-corrected density functional theory. On the oxidized surface several different local minima were identified of which the most stable corresponds to a CO(2) molecule adsorbed at a five-fold coordinated Ti site in a tilted configuration. Surface diffusion is characterized by relatively small activation barriers. Preferential diffusion takes place along Ti rows and involves a cartwheel type of motion. The presence of a bridging oxygen defect or a surface interstitial Ti atom allows creation of several new strong binding configurations the most stable of which have bent CO(2) structures with simultaneous bonding to two surface Ti atoms. Subsurface oxygen vacancy or interstitial Ti defects are found to enhance the bonding of CO(2) molecules to the surface. CO(2) dissociation from these defect sites is calculated to be exothermic with barriers less than 21 kcal/mol. The use of such defects for catalytic activation of CO(2) on anatase (101) surface would require a mechanism for their regeneration.
采用色散校正密度泛函理论研究了 CO(2)在锐钛矿（101）表面的吸附、扩散和离解。在氧化表面上，确定了几个不同的局部最小值，其中最稳定的对应于以倾斜构象吸附在五配位 Ti 位上的 CO(2)分子。表面扩散的特点是具有相对较小的激活势垒。优先扩散沿 Ti 行进行，涉及一种车轮式运动。桥氧缺陷或表面间隙 Ti 原子的存在允许形成几个新的强结合构型，其中最稳定的构型具有弯曲的 CO(2)结构，同时与两个表面 Ti 原子键合。发现亚表面氧空位或间隙 Ti 缺陷会增强 CO(2)分子与表面的结合。从这些缺陷位置解离 CO(2)的计算结果表明，其是放热的，势垒小于 21 kcal/mol。为了在锐钛矿（101）表面催化 CO(2)的活化，需要一种用于这些缺陷再生的机制。
