A conjugated polymer coupled with graphitic carbon nitride for boosting photocatalytic hydrogen generation under visible light

Abstract

In this work, a soluble C₆-alkyl chain functionalized fluorene-dibenzothiophene-S,S-dioxide (C₆-FDTP) conjugated polymer was synthesized and further used to fabricate a C₆-FDTP/g-C₃N₄ hybrid through a facile solvent–evaporation process. The polymeric heterojunction in the hybrid is composed of the FDTP backbone and tri-s-triazine of carbon nitride via π–π stacking. The performance of photocatalytic H₂ generation under visible light over C₆-FDTP/g-C₃N₄ displays 15-fold higher H₂ generation rate with respect to bare g-C₃N₄. The H₂ generation rate even achieved 495 μmol h⁻¹ g⁻¹ when Pt was used as a cocatalyst, which presented overwhelming advantages over pristine g-C₃N₄ under visible light irradiation. The enhancement mechanism was investigated by means of a series of characterization studies. Enhanced light harvesting promoted charge separation and charge transfer was identified, accounting for the superior photocatalytic activity. A type II heterostructure mechanism is assigned for the role of the C₆-FDTP conjugated polymer, and the polymeric π–π stacked heterojunction provided channels for charge separation and transfer. This work provides a research basis for the fabrication of efficient conjugated polymer photocatalysts with promising applications in industrial photocatalytic H₂ generation.