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Computational Study on Interactions between CO2 and (TiO2)n Clusters at Specific Sites
Hitler Louis1,2, Ling-ju Guo*1, Shuang Zhu1,2, Sajjad Hussain1,2, Tao He*1,2
1.Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China;2.University of Chinese Academy of Sciences, Beijing 100049, China
Abstract:
The energetic pathways of adsorption and activation of carbon dioxide (CO2) on low-lying compact (TiO2)n clusters are systematically investigated by using electronic structure calculations based on density-functional theory (DFT). Our calculated results show that CO2 is adsorbed preferably on the bridge O atom of the clusters, forming a “chemisorption” carbonate complex, while the CO is adsorbed preferably to the Ti atom of terminal Ti-O. The computed carbonate vibrational frequency values are in good agreement with the results obtained experimentally, which suggests that CO2 in the complex is distorted slightly from its undeviating linear configuration. In addition, the analyses of electronic parameters, electronic density, ionization potential, HOMO??LUMO gap, and density of states (DOS) confirm the charge transfer and interaction between CO2 and the cluster. From the predicted energy profiles, CO2 can be easily adsorbed and activated, while the activation of CO2 on (TiO2)n clusters are structure-dependent and energetically more favorable than that on the bulk TiO2. Overall, this study critically highlights how the small (TiO2)n clusters can influence the CO2 adsorption and activation which are the critical steps for CO2 reduction the surface of a catalyst and subsequent conversion into industrially relevant chemicals and fuels.
Key words:  (TiO2)n clusters, Carbon dioxide, Reduction, Adsorption, Activation
FundProject:
特定位点上CO2与(TiO2)n团簇相互作用的第一性原理研究
路易斯·希特拉1,2, 郭令举*1, 朱 双1,2, 萨贾德·侯赛因1,2, 贺 涛*1,2
1.中国科学院纳米系统与多级次制造重点实验室,纳米科学卓越创新中心,国家纳米科学中心,北京 100190;2.中国科学院大学,北京 100049
摘要:
本文基于密度泛函理论系统地研究了(TiO2)n团簇上二氧化碳(CO2)的吸附和活化性质. 计算结果表明,CO2更倾向于吸附在(TiO2)n团簇的桥氧原子上,形成“化学吸附”碳酸盐络合物. 而CO更倾向于吸附到末端Ti-O的Ti原子上. 发现计算得到的碳酸盐振动频率值与实验获得的结果非常吻合,这表明配合物中CO2的几何构型与其线性型相比,有微小的弯转. 通过对电子结构、电荷密度、电离势、HOMO-LUMO以及态密度的分析,证实了CO2与团簇之间的电荷转移以及相互作用. 从预测的能量分布图来看,(TiO2)n团簇上的CO2活化与结构密切有关,相比于块体的TiO2,CO2在团簇结构上更易于吸附和活化.
关键词:  (TiO2)n团簇,二氧化碳,还原,吸附,活化
DOI:10.1063/1674-0068/cjcp1905108
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