Adsorption of ROH molecules on TiO2 surfaces at the solid-liquid interface

VERÓNICA M. SÁNCHEZ; EZEQUIEL DE LA LLAVE; DAMIAN A SCHERLIS

LANGMUIR

AMER CHEMICAL SOC

Año: 2011 vol. 27 p. 2411 - 2419

0743-7463

The exploration of TiO2 surface reactivity from first-principles calculations hasbeen almost always limited to the gas phase, even though most of the chemically relevantapplications of this interface involve the solid-liquid boundary. The reason for this limitation isthe complexity of the solid-liquid interface,which poses a serious challenge to standard ab initiomethodologies as density functional theory (DFT). In this work we study the interaction ofH2O, CH3OH, H2O2, and HCO2H with anatase (101) and rutile (110) surfaces in aqueoussolution, employing a continuum solvation model in a DFT framework in periodic boundaryconditions [J. Chem. Phys. 2009, 131, 174108 ]. Different adsorption configurations wereanalyzed, examining the effect of the first water monolayer explicitly included in the simulation.For water and methanol, molecular adsorption was found to be the most stable in the presenceof the solvent, while for hydrogen peroxide the preferred configuration depended on the surface.The explicit inclusion of the first watermonolayer turns out to be important since it may play arole in the stabilization of the adsorbates at the interface. In general, the slightly positiveadsorption energy values obtained (with respect to water) suggest that CH3OHandH2O2 will poorly adsorb from an aqueous solution atthe titania surface. Among the three species investigated other than water, the formic acidwas the only one to exhibit a higher affinity for thesurface than H2O.