(569dy) Deconvoluting the Infrared Spectra for Water and MeOH Co-Adsorption on Anatase TiO2 Nanoshapes

Metal oxides are widely used in the catalysis community for many reactions due to their high chemical and thermal stabilities. Anatase TiO₂ is well-documented in the literature as an inexpensive and highly reactive material. Two facets stand out for this oxide: (101) for its thermodynamic stability and (001) for its reactivity. Faceted TiO₂ nanoparticles are the focus of fervid research activity as they feature the favorable properties of both facets. However, progress is hampered by the considerable gap in knowledge that still exists regarding the structural and chemical properties of these facets in the presence of adsorbates. Here we develop computational models for hydroxylated TiO₂ surfaces with co-adsorbed methanol (MeOH*) and methoxy (MeO*) to fill this knowledge gap to deconvolute the infrared vibrational spectra (Figure 1). There is agreement in the trend of the spectra, with corresponding to v(C-O) stretching (Figure 1), and higher wavenumbers corresponding to p(CH₃) rocking modes. We also find that MeO* has higher stretching frequencies than MeOH*. This work encompasses peak assignments for the CH₃ stretching mode, CO stretching, and rocking amodes. By the deconvoluting the spectra on (101) and (001) surfaces, our study represents a step forward toward controlling of reactivity of TiO₂.