A Density Functional Tight Binding Study of Acetic Acid Adsorption on Crystalline and Amorphous Surfaces of Titania

Molecules

Sergei Manzhos¹  Giacomo Giorgi²  Koichi Yamashita² 

[1] Department of Mechanical Engineering, National University of Singapore, Block EA #07-08, 9 Engineering Drive 1, Singapore 117576, Singapore;Department of Chemical System Engineering, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; E-Mails:

关键词: titanium dioxide;    anatase;    rutile;    (B)-TiO₂;    amorphous TiO₂;    acetic acid;    adsorption;    dye-sensitized solar cells;    density functional tight binding;   

DOI  :  10.3390/molecules20023371

来源: mdpi

【 摘 要 】

We present a comparative density functional tight binding study of an organic molecule attachment to TiO₂ via a carboxylic group, with the example of acetic acid. For the first time, binding to low-energy surfaces of crystalline anatase (101), rutile (110) and (B)-TiO₂ (001), as well as to the surface of amorphous (a-) TiO₂ is compared with the same computational setup. On all surfaces, bidentate configurations are identified as providing the strongest adsorption energy, E_ads = −1.93, −2.49 and −1.09 eV for anatase, rutile and (B)-TiO₂, respectively. For monodentate configurations, the strongest E_ads = −1.06, −1.11 and −0.86 eV for anatase, rutile and (B)-TiO₂, respectively. Multiple monodentate and bidentate configurations are identified on a-TiO₂ with a distribution of adsorption energies and with the lowest energy configuration having stronger bonding than that of the crystalline counterparts, with E_ads up to −4.92 eV for bidentate and −1.83 eV for monodentate adsorption. Amorphous TiO₂ can therefore be used to achieve strong anchoring of organic molecules, such as dyes, that bind via a -COOH group. While the presence of the surface leads to a contraction of the band gap vs. the bulk, molecular adsorption caused no appreciable effect on the band structure around the gap in any of the systems.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.