A novel Strategy of Lock-in Effect between Conjugated Polymer and TiO2 towards Dramatic Enhancement of Photocatalytic Activity under Visible Light

Abstract

To design novel conjugated polymers and improve interfacial interaction with semiconductor is one of directions to develop high-efficient photocatalysts with harvesting photons and boosting catalytic activities. Herein, two novel linear conjugated polymers poly[(thiophene-ethylene-thiophene)-thiophene] (PTET-T) and poly[(thiophene-ethylene-thiophene)-thiophene-3-carboxylic acid] (PTET-T-COOH) were successfully synthesized by a simple Stille coupling reaction. Their heterojunction with TiO2, i.e, PTET-T/TiO2 (C1) and PTET-T-COOH/TiO2 (C2), exhibited outstanding photocatalytic activity for degrading Rhodamine B, methylene blue and tetracycline. The energetic “lock-in effect” between PTET-T-COOH and TiO2 through carboxyl groups and hydroxyl groups interaction has been proved to greatly improve the interface charge transfer ability and suppress the electron-hole recombination in PTET-T-COOH/TiO2. Thus, by regulating the dosage of polymers, the 15% PTET-T-COOH/TiO2 showed the optimized photocatalytic activity with excellent chemical stability, and its kinetic rate constant was determined to be 41.7 times of that of TiO2. This work provided a new effective strategy of designed and explored organic semiconductor-inorganic heterojunction photocatalysts with broaden absorption, repeatability and high-charge mobility.