Modelling of ethanol decomposition on Pt(111): Ae comparison with experiment and density functional theory

Ethanol decomposition oil the clean Pt(111) surface has been studied in the zero-coverage limit within the framework of the unity bond index-quadratic exponent potential (UBI-QEP) model. Previous work, both experimental and theoretical, was already available in the literature on this reaction. The system has therefore been used as a benchmark for evaluating the accuracy of the simple phenomenological UBI-QEP model. The latter allows the estimation of key reaction parameters such as adsorption energies and reaction barriers. The stability of possible dissociation intermediates has been investigated and the most probable decomposition pathway has been simulated by integration of the related rate equations. We find that the model provides good estimates for adsorption energies of mono-coordinated molecules with long bond distances and gives realistic values for dehydrogenation barriers. Poor agreement with density functional theory (DFF) 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 found that transition and final state energies obtained from the model satisfy the linear Bronsted-Evans-Polanyi relation. Temperature programmed desorption spectra and surface coverage of the adspecies as a function of the temperature have been simulated in order to provide a direct comparison with previous experimental data. A possible pathway for ethanol decomposition oil Pt(111) is finally proposed on the basis of the present calculations, conciliating previous DFT and experimental results.