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The mechanism of H-2 and H2O desorption from bridging hydroxyls of a TiO2(110) surface
Wang, Ruimin1,2; Fan, Hongjun1,2
Source PublicationCATALYSIS SCIENCE & TECHNOLOGY
2017
DOI10.1039/c6cy02007k
Volume7Issue:1Pages:251-264
Indexed BySCI
SubtypeArticle
WOS HeadingsScience & Technology ; Physical Sciences
WOS SubjectChemistry, Physical
WOS Research AreaChemistry
WOS KeywordMOLECULAR-HYDROGEN FORMATION ; MINIMUM ENERGY PATHS ; ELASTIC BAND METHOD ; RUTILE TIO2(110) ; AB-INITIO ; TIO2 PHOTOCATALYSIS ; SADDLE-POINTS ; ADSORPTION ; METHANOL ; WATER
AbstractThe photocatalytic H-2 production from H2O over TiO2 has attracted tremendous attention in recent years, and great progress has been achieved in light adsorption and water dissociation. As a comparison, the H-2 and O-2 production over a pure TiO2 surface has not been successful yet. Recently, the desorption of bridging hydroxyls (BBOHs) to form H-2 has been found to be possible on a TiO2(110) surface. However, the yield of H-2 is low, and the majority of BBOHs desorb as H2O. Here, for the first time, we have systematically studied the mechanism of H-2 desorption and the competition of H-2 and H2O desorption on a TiO2(110) surface with DFT methods. We found that the generally believed pathway, the direct coupling of BBOHs, is not the most facile pathway. We propose that the reaction undergoes a Ti-H key intermediate, which then forms an O-H delta+center dot center dot center dot H delta--Ti type dehydrogenation transition state. On a stoichiometric surface, the barriers for H-2 desorption and H2O desorption are 2.20 eV and 1.09 eV, respectively. However, with an increase in BBO vacancies (Ovs, created by H2O desorption), the barrier for H-2 desorption decreases, while the barrier for H2O desorption increases. Specifically, H-2 desorption was found to be easier than H2O desorption with our two Ovs TiO2 model. Therefore, our results predict that H2O desorption is dominant at the beginning, then H-2 desorption becomes more and more competitive. This prediction perfectly fits with the experimental observations. Furthermore, the stability of the key Ti-H intermediates and the possible ways for changing the conditions of H-2 desorption have also been discussed.
Language英语
WOS IDWOS:000392399900023
Citation statistics
Document Type期刊论文
Identifierhttp://cas-ir.dicp.ac.cn/handle/321008/151863
Collection中国科学院大连化学物理研究所
Affiliation1.Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Mol React Dynam, 457 Zhongshan Rd, Dalian 116023, Liaoning Provin, Peoples R China
2.Univ Chinese Acad Sci, 19 A Yuquan Rd, Beijing 100049, Peoples R China
Recommended Citation
GB/T 7714
Wang, Ruimin,Fan, Hongjun. The mechanism of H-2 and H2O desorption from bridging hydroxyls of a TiO2(110) surface[J]. CATALYSIS SCIENCE & TECHNOLOGY,2017,7(1):251-264.
APA Wang, Ruimin,&Fan, Hongjun.(2017).The mechanism of H-2 and H2O desorption from bridging hydroxyls of a TiO2(110) surface.CATALYSIS SCIENCE & TECHNOLOGY,7(1),251-264.
MLA Wang, Ruimin,et al."The mechanism of H-2 and H2O desorption from bridging hydroxyls of a TiO2(110) surface".CATALYSIS SCIENCE & TECHNOLOGY 7.1(2017):251-264.
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