Density Functional Investigation of the Adsorption of Ethanol–Water Mixture on the Pt(111) Surface

Steam reforming of ethanol–water mixture is a promising renewable route to obtain hydrogen; however, our atomistic understanding of the interaction of ethanol–water mixture with transition-metal surfaces is far from satisfactory. In this work, we report a density functional theory investigation of the adsorption properties of the ethanol–water mixture on the Pt(111) surface employing semilocal exchange-correlation functional within nonlocal van der Waals corrections. From our calculations and analysis, we found that water molecules are located near the surface instead of ethanol, which is in contrast with our initial expectation based on the large magnitude of the adsorption energy of ethanol on Pt(111) compared with water/Pt(111). We found that the formation of hydrogen bonds among ethanol–ethanol, water–water, and ethanol–water molecules plays an important role in the adsorbate structure of the ethanol–water mixture on Pt(111), in particular, due to the enhancement of the binding energy of the hydrogen bonds induced by the interaction with the Pt(111) surface. We found that the van der Waals correction does not strongly affect the adsorbate structures of the ethanol–water mixture; however, as expected, it enhances the adsorption energy, which is coverage-dependent. Furthermore, we also report results and analysis for the adsorption of ethanol and water molecules on the Pt(111).