resumo
The geometry, energy and stretching frequency of carbon monoxide on the rutile TiO2(110) surface for coverages between 0.125 and 1.5 ML are investigated by means of density functional theory calculations. Four different approaches were considered, namely, the PBE exchange-correlation functional and the PBE-D2, vdW-DF and vdW-DF2 methods incorporating van der Waals dispersion interactions of different theoretical complexity and empiricism. It is found that upon the increase of the surface coverage, the adsorption becomes less favorable due to lateral destabilizing interactions between adsorbed molecules. The preferred geometry for CO changes from an upright configuration at 0.125 ML to tilted configurations at 1.5 ML and the tilting of the C-O axis from the surface normal increases with the increase of the surface coverage. At 1 ML, all computational approaches predict alternate tilted configurations which contradict the interpretation of recent experimental infrared reflection-absorption spectroscopic findings suggesting upright CO geometries. Encouragingly, a very good agreement between calculated and experimental shifts of the C-O stretching frequency of adsorbed CO at different coverages with respect to gaseous CO species was reached.
palavras-chave
GENERALIZED GRADIENT APPROXIMATION; SPECTROSCOPY; TIO2; PRINCIPLES; CLUSTER; SCIENCE; ENERGY
categoria
Chemistry; Physics
autores
Ramalho, JPP; Illas, F; Gomes, JRB
nossos autores
José R. B. Gomes
Investigador Principalagradecimentos
JPPR and JRBG are grateful to Fundacao para a Ciencia e a Tecnologia (FCT). This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), project CQE-Centro de Quimica de Evora (Ref. FCT UID/QUI/0619/2016), project HERCULES lab (Ref. FCT UID/Multi/04449/2013) and Programa Investigador FCT, financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement. The research of FI has been supported by Spanish MINECO/FEDER grant CTQ2015-64618-R and, in part, by Generalitat de Catalunya grants (2014SGR97 and XRQTC) and from the NOMAD Center of Excellence project; the latter project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 676580. FI also acknowledges additional support through 2015 ICREA Academia award for excellence in university research.