Y. Iwasawa et al., The selective adsorption and kinetic behaviour of molecules on TiO2(110) observed by STM and NC-AFM, FARADAY DIS, (114), 1999, pp. 259-266
In the present paper we report a kinetic aspect of molecules on terraces an
d steps of a TiO2(110)-(1x1) surface as observed by scanning probe microsco
py, which may be relevant to oxide catalysis. When the TiO2 surface, heated
at 400-450 K, was exposed to a formic acid ambient of 1-2x10(-6) Pa, small
particles were formed on terraces. Post-reaction STM observation revealed
that the particle formation was strongly suppressed in the vicinity of sing
le-atom height steps. The suppressive effect of the steps ranged 2.4 nm int
o the terrace. Formate ions (a possible reaction intermediate) were imaged
in-situ during formic acid exposure at the reaction temperature. The local
density of the formates and hence the product distribution, which were very
low near the steps, were simulated by a model. The particles produced were
suggested to be carbonates, CO32- on the bridging oxygen atoms of the TiO2
(110) surface.