Location Effect in a Photocatalytic Hybrid System of Metal-Organic Framework Interfaced with Semiconductor Nanoparticles

We report an ultrafast spectroscopy investigation that addresses the subtle location effect in a prototypical semiconductor-MOF hybrid system with TiO2 nanoparticles being incorporated inside or supported onto Cu-3 (BTC)(2), denoted as TiO2 @Cu-3 (BTC)(2) and TiO2/Cu-3(BTC)(2), respectively. By tracking in real time the interface electron dynamics in the hybrid system, we find that the interface states formed between TiO2 and Cu-3(BTC)(2) can act as an effective relay for electron transfer, whose efficiency rests on the relative location of the two components. It is such a subtle location effect that brings on difference in photocatalytic CO2 reduction using the two semiconductor-MOF hybrids. The mechanistic understanding of the involved interface electron-transfer behavior and effect opens a helpful perspective for rational design of MOF-based hybrid systems for photoelectrochemical applications.