Self-assembled A–D–A type indacenodithiophene-based small conjugated molecule/TiO2 for enhancing the photocatalytic activity

Abstract

Herein, A–D–A type indacenodithiophene-based small conjugated molecule IDT-COOH and IDT-COOH/TiO₂ photocatalysts with stable non-covalent bonding have been successfully synthesized via in situ electrostatic assembly. The self-assembled three-dimensional π-conjugation structure IDT-COOH with high crystallinity not only broadens the visible absorption to produce more photogenerated carriers but also provides directional charge-transfer channels to accelerate the charge mobility. Thus, 7 log inactivation of S. aureus in 2 h and 92.5% decomposition of TC in 4 h under visible light exposure are achieved for optimized 30% IDT-COOH/TiO₂. The dynamic constants (k) of S. aureus disinfection and TC degradation for 30% IDT-COOH/TiO₂ are 3.69 and 2.45 times compared to those of self-assembled IDT-COOH, respectively. The notable inactivation performance is among the best reported for conjugated semiconductor/TiO₂ photocatalysts for photocatalytic sterilization. ˙O₂⁻, e⁻ and ˙OH are the primary reactive species in the photocatalytic process. The strong interfacial interaction between TiO₂ and IDT-COOH is in favour of rapid charge transfer, which leads to enhanced photocatalytic performance. This work offers a feasible method to fabricate TiO₂-based photocatalytic agents with a wide visible light response and improved exciton dissociation.