Hot-Electron-Induced Highly Efficient O2 Activation by Pt Nanoparticles Supported on Ta2O5 Driven by Visible Light

Abstract

Aerobic oxidation on a heterogeneous catalyst driven by visible light (λ >400 nm) at ambient temperature is a very important reaction for green organic synthesis. A metal particles/semiconductor system, driven by charge separation via an injection of "hot electrons (e(hot)(-))" from photoactivated metal particles to semiconductor, is one of the promising systems. These systems, however, suffer from low quantum yields for the reaction (373 K). Here we report that Pt nanoparticles (∼5 nm diameter), when supported on semiconductor Ta2O5, promote the reaction without e(hot)(-) injection at room temperature with significantly high quantum yields (∼25%). Strong Pt-Ta2O5 interaction increases the electron density of the Pt particles and enhances interband transition of Pt electrons by absorbing visible light. A large number of photogenerated e(hot)(-) directly activate O2 on the Pt surface and produce active oxygen species, thus promoting highly efficient aerobic oxidation at room temperature.