Gold Nanoparticles on Titania: Activation and Behavior
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Gold nanoparticles supported on titania show a high activity in many catalytic processes, including the oxidation of CO and the destruction of SO2. This is a remarkable phenomenon because surfaces of bulk metallic gold are not good catalysts. In recent years, many experimental and theoretical studies have been focused on understanding the high catalytic activity of gold nanoparticles supported on titania. Quantum effects related to the small size of the particles could be responsible for the enhancement in catalytic activity with respect to bulk gold, but it is becoming increasingly clear that interactions between the gold nanoparticles and the titania support plays a very important role. In this contribution, a review is presented of studies dealing with the behavior of a well-defined system such as Au/TiO2(110). The edge and corner sites of a gold nanoparticle (i.e., sites having three to four metal atom neighbors) can bond well adsorbates such as CO, O2, and SO2. They can even perform the catalytic oxidation of CO, but for more demanding reactions, the chemical activity of the isolated Au nanoparticles is not enough. A comparison of the DeSOx activity for the Au/TiO2(110) and Au/MgO(100) surfaces illustrates the important role played by gold–titania interactions. The titania support is not a simple spectator.