Porous organic polymer composites as surging catalysts for visible-light-driven chemical transformations and pollutant degradation

The promising aspect of photocatalysis to effectively utilize the abundant solar irradiation for promoting various chemical reactions and environmental remediation at greener, low-energy demanding conditions resulted in the recent surge in this research field. In this review, the synthesis and structure-property relationships of photoactive porous organic polymers (POPs) followed by their environmentally benign applications including various chemical transformations and decontamination of pollutants involving key intermediate reactive species have been critically discussed. The conditions required to generate these active species such as photo-generated electron and hole pair, singlet oxygen, superoxide, organic radical, etc. and their different quenching pathways are initially explained to clearly portray the favourable settings necessary for efficient POP-photocatalysis. This introductory discussion is further extrapolated to systematically illustrate the structure-application correlation of every visible-light-responsive POPs reported to date. The mechanisms adapted by POPs for photocatalytic organic reactions and degradation of wastewater pollutants have been comprehensively depicted. Initial discussion on reactive species is envisioned to provide a clear grasp on these later-explained mechanistic pathways. The review is finally concluded by crucially explaining the existing limitations and future development prospects of this field.