Oxide-metal Interfaces as Active Sites for Acid-base Catalysis: Oxidation State of Nanocatalyst Change with Decreasing Size, Conversion of Heterogeneous to Homogeneous Catalysis, Hybrid Systems
When metal nanoparticles are placed on different mezoporous or microporous oxide supports the catalytic turnover rates and selectivities markedly change. The charge flow between the metal and the oxide ionizes the adsorbed molecules at the oxide-metal interfaces and alters the catalytic chemistry (acid-base catalysis).
The oxidation state of metal nanoparticles becomes less metallic and assume higher oxidation states with decreasing size. The small nanoclusters behave similar to transition metal ions that are active homogeneous catalysts. Hybrid systems composed of enzymes, homogeneous and heterogeneous catalysts are constructed to study molecularly unified catalytic schemes for the future.