Investigating the Photocatalytic Performances of Nanocomposites Containing Narrow-band-gap Copolymers and ZnO

Composites of ZnO and conjugated polymers find applications in removal of polluting dyes from industrial wastes. The choice of functionality and repeating unit of polymer is important to improve the efficacy of the process. While heterocyclic diketopyrrolopyrrole (DPP) -based polymers are often considered as the most promising donor moiety in traditional bulk heterojunction solar cell devices, benzothiadiazole-based polymers are reported to show the best performance as photosensitizer for dye degradation. In this paper, we report for the first time the preparation of copolymers containing both the above mentioned heterocyclic repeating units linked directly or by a double bond. We were delighted to observe broad spectrum of substantial light absorption from UV to NIR range and a low band gap for one of the polymers, the main reason behind higher efficacy in dye removal under sunlight. Finally, we studied the efficacy of the polymers as photosensitizer for ZnO promoted dye degradation process which showed almost a complete degradation of a model dye only within two hours, one of the best results reported recently using the conjugated polymers.