Design of AIEgen-based porphyrin for efficient heterogeneous photocatalytic hydrogen evolution : special collection : aggregation-induced processes and functions

Abstract

Tetraphenylethylene (TPE)-conjugated porphyrin TPE-ZnPF is synthesized in high yield and characterized by single-crystal X-ray diffraction. The propeller-shaped TPE groups not only enable exceptional aggregation-induced emission (AIE) in the solid state but also abolish the strong π-π stacking of porphyrin moieties and thus prohibit aggregation-caused quenching (ACQ). TPE-ZnPF aggregates feature long-lived photoexcited states, which subsequently suppress non-radiative decay channels and enhance emission intensity. Moreover, its aggregates show more efficient light-harvesting ability due to the Förster resonance energy transfer from the TPE energy donor to the porphyrin core energy acceptor, well-defined nanosphere morphology, and more efficient photoinduced charge separation than the porphyrin Ph-ZnPF, which possesses ACQ and agglomerated morphology. As a result, an excellent photocatalytic hydrogen evolution rate (ηH2) of 56.20 mmol g‒1 h‒1 is recorded for TPE-ZnPF aggregates, which is 94-fold higher than that of the aggregates of Ph-ZnPF (0.60 mmol g‒1 h‒1) without the TPE groups.