Modulating the surface defects of titanium oxides and consequent reactivity of Pt catalysts

In heterogeneous catalysis, it is widely believed that the surface states of catalyst supports can strongly influence the catalytic performance, because active components are generally anchored on supports. This paper describes a detailed understanding of the influence of surface defects of TiO₂ supports on the catalytic properties of Pt catalysts. Pt was deposited on reduced (r-), hydroxylated (h-), and oxidized (o-) TiO₂ surfaces, respectively, and the different surface states of TiO₂ not only lead to differences in metal dispersion, but also distinct electronic interactions between the metal and the support. The highest reactivity for catalytic CO oxidation can be achieved over the Pt catalyst supported on reduced TiO₂ with surface oxygen vacancies. The turnover frequency (TOF) of this catalyst is determined to be ∼11 times higher than that of Pt supported on oxidized TiO₂. More importantly, the reactivity is seen to increase in the sequence of Pt/o-TiO₂ < Pt/h-TiO₂ < Pt/r-TiO₂, which is well consistent with the trend of the calculated Bader charge of Pt.