Formaldehyde adsorption and decomposition on rutile (110): A first-principles study

SURFACE SCIENCE

卷:652

Article

Liu, Liming^1,2  Zhao, Jin^1,2,3,4,5 

[1] Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui, Peoples R China

[2] Univ Sci & Technol China, Dept Phys, Hefei 230026, Anhui, Peoples R China

[3] Univ Sci & Technol China, Synerget Innovat Ctr Quantum Informat & Quantum P, Hefei 230026, Anhui, Peoples R China

[4] Chinese Acad Sci, Univ Sci & Technol China, Sch Phys Sci, Key Lab Strongly Coupled Quantum Matter Phys, Hefei, Peoples R China

[5] Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA

关键词: DFT;    Formaldehyde decomposition;    Photocatalytic reactivity;   

DOI  :  10.1016/j.susc.2015.12.036

来源: Elsevier

【 摘 要 】

We investigated the adsorption and decomposition of formaldehyde (HCHO) molecule on stoichiometric rutile TiO2(110) surface using first principles-calculations. By comparing the adsorption energy of one bidentate and two monodentate configurations, we found the bidentate configuration is the most stable one because of an additional C-O bond formation. The monodentate configuration can change into the bidentate configuration by overcoming a small barrier less than 0.1 eV. Then, we investigated the decomposition of HCHO which involves two deprotonation processes starting from different adsorption structures. The energy barrier of the first deprotonation is 1.3 eV and 1.1 eV for bidentate and monodentate configurations. After the first deprotonation, an adsorbed formate HCOO specie is formed. The second deprotonation needs 1.74 eV and 1.64 eV for bidentate and monodentate configurations, respectively. After that, an adsorbed CO2 is formed. It can desorb from the surface after overcoming a small barrier of 0.12 eV. In principle, it is also possible to obtain a CO molecule from the surface. Yet a large energy barrier higher than 1.74 eV needs to be overcome. By analyzing the energy level alignment of molecular orbitals with TiO2 energy band edges, we discussed the photocatalytic activity of the reactants and intermediates during the decomposition process. Our results give a clear description of the adsorption structure and thermal decomposition process of HCHO on rutile TiO2(110) surface. The discussion of photocatalytic reactivity based on energy level alignment provides valuable insights to understand the combined photocatalytic and thermally catalytic reactions. (C) 2016 Elsevier B.V. All rights reserved.

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