Synthesis of donor-acceptor-type conjugated polymer dots as organic photocatalysts for dye degradation and hydrogen evolution

Conjugated polymers (CPs) having various donor-acceptor units in the main chain were synthesized via Suzuki coupling reaction for an organic photocatalyst that can generate reactive oxygen species (ROS) for dye degradation and H2 evolution under visible-light irradiation. To synthesize four kinds of CPs, two donor units (phenylene and fluorene) and two acceptor groups (benzothiadiazole and bisthienylbenzothiadiazole) were cross-combined. The cyclic voltammograms of the CPs showed their generation ability for ROS, in which the ROS generation efficiency would depend on the main chain structure. Because the CPs are inherently hydrophobic, they were fabricated in nanoparticle (NP) form for convenient use in an aqueous solution. The CP NPs showed excellent dye degradability under visible light. In addition, CPs were incorporated in a filter paper to provide repeated uses after simple washing. The ROS generation from CPs played an important role in dye degradation, as well as in H2 evolution of up to 8.4 mmol/g under visible-light irradiation.