Scheme 1. An Example of a Fully-Exposed Cluster Catalyst (i.e., Pt₁₃ Cluster Loaded on the TiO₂ Surface).

In the side (a) and top (b) view of the Pt₁₃/TiO₂ FECC, the level of color highlights the charge of Pt atom from Bader charge analysis. The bar on the top right marks the value of the charge, and the lighter color indicates a stronger charge transfer from the Pt atom to the substrates. Clearly, the charge of the Pt atoms in contact directly with oxide substrate are more positive, while those in the 2nd layer preserve more metallic characteristics.