Highly Efficient Water Dissociation on Anatase TiO₂(101)

Abstract

Photoinduced water dissociation on anatase-TiO₂(101) has\nbeen investigated using a laser surface photolysis technique, in combination\nwith temperature-programmed desorption and time-of-flight methods.\nGaseous OH radicals have been clearly detected by the time-of-flight\nmethod during laser irradiation. Further result reveals that the water\ndissociation reaction occurs most likely via transferring a H atom\nto a two coordinated oxygen site nearby and ejecting an OH radical\nto the gas phase. As the water coverage increases, the yield of the\nwater dissociation reaction is also enhanced, whereas the dissociation\nprobability of water is nearly the same at different water coverages.\nIn comparison with water dissociation on rutile-TiO₂(110)\nwhere the dissociation probability of water is largely inhibited by\nthe strong hydrogen bonds at high water coverage, the reaction on\nanatase-TiO₂(101) is considerably more efficient at high\nwater coverage, which is most likely due to the much weaker interaction\nbetween water molecules on the surface. This provides an important\nclue that strong hydrogen bond interaction should be avoided on a\ngood photocatalyst for water dissociation.