Stability of Formate Species on â-Ga2O3: A Combined DFT and IR Investigation.

M. CALATAYUD; S.E. COLLINS; M.A. BALTANÁS; A.L. BONIVARDI

Lyon (Francia), agosto 31-setiembre 4.

Conferencia; 13th International Conference on the applications of Density Functional Theory in Chemistry and Physics; 2009

Gallia (gallium oxide) is a technologically promising material in ceramics, electronic devices, gas-sensing and catalytic processes. Particularly, gallia has proved to enhance the performance of metal catalysts for the production of hydrogen from methanol steam reforming, the methanol synthesis from selective hydrogenation of carbon dioxide and the (inverse) water gas shift reaction. The presence of formate species as key intermediates in the previous reactions has been reported, although their role is still a matter of debate. In this work, a combined theoretical and experimental approach has been carried out in order to characterize the formation of such formate species over the gallium oxide surface. Infrared spectroscopy experiments of CO adsorption over H2 (or D2) pretreated b-Ga2O3 revealed the formation of several formate species. The b-Ga2O3 (1 0 0) surface was modeled by means of periodic DFT calculations. The stability of said species and their vibrational mode assignments are discussed together with the formate interconversion barriers. The monocoordinate formate would play a key role as intermediate in the CO oxidation.