Light-harvesting photocatalysis for H2 evolution by methylacridone-bridged periodic mesoporous organosilica

Abstract

Photocatalytic H2 production from water is one approach to solving global energy problems. Much attention has been paid to the promising applications of solid-state molecular photocatalysts because of their ease of handling, recyclability, and designable catalytic properties. We report an efficient photocatalytic H2 evolution system using methylacridone (MeAcd)-bridged periodic mesoporous organosilica (MeAcd-PMO), which has visible light absorption and electron-donating properties. MeAcd-PMO loaded with Pt nanoparticles efficiently generated H2 under visible light irradiation with a high apparent quantum yield (8.6% at 400 nm). Transient absorption measurements revealed a unique light-harvesting mechanism involving the excitation energy migration of the lowest singlet excited state on the MeAcd-PMO framework, which has not been observed in conventional solid-state molecular photocatalysts. MeAcd-PMO exhibiting this energy migration behavior is expected to be useful as a host material for constructing efficient photocatalytic systems which mimic natural photosynthesis