Modelling of ethanol decomposition on Pt(111): a comparison with experiment and densityfunctional theory

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Ethanol decomposition on the clean Pt(111) surface has been studied in the zero-coveragelimit within the framework of the unity bond index-quadratic exponent potential(UBI-QEP) model. Previous work, both experimental and theoretical, was already availablein the literature on this reaction. The system has therefore been used as a benchmark forevaluating the accuracy of the simple phenomenological UBI-QEP model. The latter allowsthe estimation of key reaction parameters such as adsorption energies and reaction barriers.The stability of possible dissociation intermediates has been investigated andthe most probable decomposition pathway has been simulated by integration ofthe related rate equations. We find that the model provides good estimates foradsorption energies of mono-coordinated molecules with long bond distances and givesrealistic values for dehydrogenation barriers. Poor agreement with density functionaltheory (DFT) is found in the estimates of C–C and C–O bond cleavage barriers,even though the results obtained are in line with the experiments. It is foundthat transition and final state energies obtained from the model satisfy the linearBrønsted–Evans–Polanyi relation. Temperature programmed desorption spectra and surfacecoverage of the adspecies as a function of the temperature have been simulated inorder to provide a direct comparison with previous experimental data. A possiblepathway for ethanol decomposition on Pt(111) is finally proposed on the basis ofthe present calculations, conciliating previous DFT and experimental results.