The interaction of water with the Pt(533) surface

The adsorption of water on the stepped Pt(533) surface has been investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). Both the TPD spectra and the RAIRS results reveal two submonolayer states and one multilayer phase. In the submonolayer regime, water first adsorbs on the Pt(100)-step edges of the surface. The water molecules at these steps induce a supplementary stabilization of the water that subsequently adsorbs onto the four atoms wide (111) terraces. In contrast, the multilayer TPD feature is not affected by the stepped nature of the substrate and is very similar to water desorption from, for example, the flat Pt(111) surface. RAIRS data indicate strong hydrogen-bonding interactions between water molecules adsorbed on the steps already at very low coverages (< 0.13 ML). This is in agreement with DFT calculations that demonstrate that the water-water interaction is sufficiently strong that water molecular chains could be formed along the step edges at very low coverage. Both the RAIRS data and the DFT calculations support intact H₂O adsorption on Pt(533).