Understanding the interactions of simple carboxylic acids, such as formic and acetic acids, with oxide surfaces is of great importance for many catalytic reactions. Comparative studies of the adsorption and reaction of acetic acids on single-crystalline and facetted-nanoparticle anatase TiO<sub>2</sub>(101) will be presented. A combination of scanning tunneling microscopy, infrared reflection absorption spectroscopy, temperature programmed desorption, and density functional calculations are employed to obtain mechanistic insight into the adsorption, diffusion, clustering, and product formation. The deprotonated bidentate (BD) species is determined to be thermodynamically preferred. Metastable, molecularly-bound monodentate (MD) is also observed and found to be stabilized at high coverages in mixed MD-BD phases. The dynamics of bidentate diffusion is controlled by spatial configurations of neighboring hydroxyls and by proximity to other BDs. A new type of BD species is observed above room temperature, likely due to the reaction with oxygen vacancies. At high temperatures (&gt; 400 K), BD acetate yields ketene and water under ultrahigh vacuum conditions. On faceted nanoparticles, the dominant reaction channel shifts from monomolecular dehydration to ketene to bimolecular carbon-carbon coupling, yielding acetone as the pressure increases. Combined, these studies provide a detailed mechanistic insight into the elementary steps of model catalytic reactions.

Elementary steps in catalytic reactions of acetic acids on anatase TiO<sub>2</sub>(101) single crystals and faceted nanoparticles

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Elementary steps in catalytic reactions of acetic acids on anatase TiO2(101) single crystals and faceted nanoparticles

Elementary steps in catalytic reactions of acetic acids on anatase TiO₂(101) single crystals and faceted nanoparticles