Fluorine substituent effect on the adsorption of acetic acid derivatives (CH3−n FnCO2H) on anatase TiO2 (100) and (101) surfaces

• Published in: Applied surface science Vol. 357; pp. 1260 - 1267
• Main Authors: Rezaei, Masoume, Najafi Chermahini, Alireza, Dabbagh, Hossein A., Teimouri, Abbas
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2015
• Subjects: Acetic acid; Adsorption; Anatase surface; Density functional theory; Derivatives; Difluoroacetic acid; Fluorination; Fluorine; Fluoroacetic acid; Mathematical analysis; Surface chemistry; Titanium dioxide; Trifluoroacetic acid; Density functional theory; Anatase surface; Trifluoroacetic acid; Acetic acid; Fluoroacetic acid; Difluoroacetic acid
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.09.153

•Adsorption of acetic acid derivatives on anatase TiO2 surfaces was modeled by periodic DFT method.•The HOMO, LUMO and HOMO–LUMO energy gap varies for the adsorption of acetic acid derivatives.•Adsorption of acetic acid derivatives on (101) surface occurred via a proton transfer reaction. A density functional theory method was used to investigate the adsorption of acetic acid and its fluorinated derivatives on (100) and (101) surfaces of anatase TiO2. It was found that while the adsorption of acetic acid and its fluorinated derivatives on the (100) surface of TiO2 does not proceeds via a proton transfer process but surprisingly adsorption on (101) surface occurred via a complete proton transfer reaction. The calculated interaction energies for adsorption on (100) surface are −19.22, −18.36, −15.73, and −60.68kcal/mol for acetic, fluoroacetic, difluoroacetic, and trifluoroacetic acid, respectively. Similar trend observed for absorption on (101) surface and calculated interaction energies are −25.35, −23.16, −23.02, and −69.47kcal/mol, respectively. Structurally, calculations show that when the number of fluorine substituent increases, the length of hydrogen bonding between OH group and neighboring oxygen positioned 2c (O2c) atom is diminished. The HOMO, LUMO and HOMO–LUMO energy gap varies for the adsorption of acetic acid derivatives on both (100) and (101) surfaces changed in comparison with clean TiO2 surface. The Fermi levels were also changed after adsorption of acetic acid derivatives.