Influence of Au and TiO_2 structures on hydrogen dissociation over TiO_2/Au(100)

摘要

We performed H_2-D_2 exchange reactions over TiCVAu(100) and compared the observed reaction kinetics with those reported for TiO_x/Au(l11) 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.