Influence of Au and TiO ₂ structures on hydrogen dissociation over TiO ₂/Au(100)

We performed H ₂-D ₂ exchange reactions over TiO _x/Au(100) and compared the observed reaction kinetics with those reported for TiO _x/Au(111) in order to clarify the influence of the Au and TiO ₂ structures on dissociation of H ₂ molecules. Low energy electron diffraction observations showed that the TiO ₂ produced on Au(100) was disordered, in contrast to the comparatively ordered TiO ₂ structure formed on Au(111). The activation energies and the turnover frequencies for HD formation over TiO ₂/Au(100) agreed well with those for TiO ₂/Au(111), clearly indicating that the hydrogen dissociation sites created over TiO ₂/Au(100) were the perimeter interface between stoichiometric TiO ₂ and Au, as was previously concluded for TiO ₂/Au(111). We concluded that the creation of active sites for hydrogen dissociation was independent of the Au and TiO ₂ structures consisting perimeter interface, and that local bonds that formed between Au and O atoms of stoichiometric TiO ₂ were essential for the creation of active sites.