Dual enhancement of carrier generation and migration on Au/g-C3N4 photocatalysts for highly-efficient broadband PET-RAFT polymerization

Abstract

Photoinduced electron/energy transfer RAFT (PET-RAFT) polymerization can produce well-defined polymers with spatiotemporal control. Semiconducting graphitic carbon nitride (g-C₃N₄), as a thermally and chemically stable photocatalyst, has accomplished the PET-RAFT method under UV-irradiation and blue-light. However, its catalytic efficiency was decreased by the high recombination rate of photogenerated electron–hole pairs, while the control over polymerization was weakened by the ultraviolet-decomposition of RAFT reagents. Herein, a series of Au/g-C₃N₄ composite photocatalysts were facilely prepared by the deposition–precipitation method. Arrangement of Au nanoparticles (NPs) on g-C₃N₄ displayed hot electron injection or plasmon-induced resonance energy transfer, which boosts the generation of active electrons for a broadband PET-RAFT process (460–740 nm). The formation of a Schottky barrier enhanced the carrier migration, as it lowered the charge recombination rate. Such a synergistic effect made Au/g-C₃N₄ outperform Au NPs, g-C₃N₄ and their physical blend. Furthermore, the effects of the Au content, hole scavenger, chain transfer agent, monomer, solvent, and light-source on the highly efficient PET-RAFT polymerization were studied.