Intrinsically microporous polyimide-based metal-free catalysts for round-the-clock photodegradation of organic pollutants

Photocatalytic degradation of organic pollutants is an essential technology for various environmental applications. However, the effectiveness of most photocatalysts is restricted to light. Herein, we report metal-free catalysts derived from intrinsically microporous polyimide for persistence in photocatalytic degradation of dyes. We systematically investigate the effect of porosity and functionality on photocatalytic efficiency. Both the pristine 4,4′-(hexafluoroisopropylidene)diphthalic anhydride-3,3′-dimethylnaphthidine and its thermally annealed counterpart at 530 °C exhibit high charge storage capabilities, enabling continuous photodegradation in the absence of light. The pre-irradiated catalyst exhibits an approximately 99% degradation of the dye, with a ~40% improvement relative to the non-pre-irradiated sample. We studied the influence of the chemical structure and porosity on the photocatalytic degradation efficiency in darkness by varying the polyimide chemical structure using different diamines. This research underscores the potential of polymers with intrinsic microporosity for application in the continuous degradation of dyes, contributing to the pursuit of cleaner water. Photodegradation of pollutants is important to produce clean water but their activities are restricted during nighttime. Here, metal-free catalysts derived from intrinsically microporous polyimide show efficient photocatalytic degradation activities of dyes under light and darkness.