Due to their geometric and electronic properties, perovskites (ABO3) have emerged as effective heterogeneous catalysts for redox reactions and, more recently, for acid-base reactions. As a first step to developing fundamental theoretical models of acid-base catalysis at perovskite surfaces, we have studied the adsorption of three small alcohol molecules, ethanol, isopropanol, and sec-butanol on the (100) surface of strontium titanate (SrTiO3) using density functional theory (DFT). Results show that the adsorption of alcohols on the SrTiO3(100) surface is quite complex and occurs in multiple steps. First, the alcohol adsorbs molecularly to a titanium site on the surface and then dissociatively chemisorbs on the surface by undergoing deprotonation of the hydroxyl proton. The adsorbed alkoxy species exists in an equilibrium of two forms based on the formation and breakage of a hydrogen bond between the alkoxy species and the surface. The relative stabilities of the different adsorption states depend on the basicity of the surface as well as on the nature of the alcohol. Importantly, the different adsorbed forms of the alcohol have different adsorption geometries and orientations and might therefore promote different reaction pathways. Future work will test this hypothesis by computing reaction pathways for dehydration and dehydrogenation of the adsorbed alcohol molecules and investigating whether the adsorption orientation plays a key role in dictating the selectivity of the catalyst.

Effects of adsorption on selective transformations of small alcohol molecules on the strontium titanate(100) surface

2019 Fall National Meeting

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