Monoethanolamine Adsorption on TiO2(110): Bonding, Structure, and Implications for Use as a Model Solid-Supported CO2 Capture Material

• Published in: Journal of physical chemistry. C 2014-01, Vol.118 (3), p.1576-1586
• Main Authors: Müller, Kathrin, Lu, Deyu, Senanayake, Sanjaya D, Starr, David E
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp409098p

We have studied the adsorption of monoethanolamine (MEA, HO(CH2)2NH2), a well-known CO2 capture molecule, on the rutile TiO2(110) surface using a combined experimental and theoretical approach. X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and scanning tunneling microscopy measurements indicate that MEA adsorbs with the oxygen atom of the hydroxyl group and the nitrogen atom of the amine group bonded to adjacent 5-fold coordinated Ti-sites (Ti(5f)) in the Ti-troughs, leading to a saturation coverage of 0.5 ML at room temperature. Density functional theory calculations confirm that this adsorption configuration is the most stable one with an adsorption energy of 2.33 eV per MEA molecule. The bonding of MEA to TiO2(110) is dominated by local donor–acceptor bonds between the oxygen and nitrogen atoms of the MEA molecule and surface Ti(5f) sites. Hydrogen bonds between adjacent MEA molecules stabilize the adsorption structure at saturation coverage. The implications of this bonding configuration for the use of MEA/TiO2(110) as a model CO2 capture material will be discussed.