Green synthesis of hypercrosslinked polymers for CO₂ capture and conversion: recent advances, opportunities, and challenges

The growing demand for fuel and industrial products has resulted in increased global CO2 emissions, which has accelerated global warming and made this an issue of widespread concern. Therefore, there is an urgent need to develop improved methods for CO2 fixation and conversion. Porous organic polymers (POPs) are solid frameworks that can be used for this purpose and can be prepared by so-called "bottom-up" methods. Being one kind of POP, hypercrosslinked polymers (HCPs) have emerged as a promising platform for CO2 capture and conversion, because of their high specific surface areas, variable pore characteristics, superior stabilities, and modifiable surface functionalities. In addition, innovative green methods of synthesis enable the environmentally friendly production of HCPs. In this review, we provide an update on the synthesis and utilization of HCPs for CO2 capture and conversion. First, we introduce green routes for the synthesis of HCPs, followed by a comprehensive summary of various methods for CO2 capture and conversion. Our primary emphasis is on the utilization of HCPs for CO2 fixation (gas storage) and gas separation, with particular attention given to CO2 selectivity and recoverability. Additionally, we explore the potential of HCPs in the conversion of CO2 into valuable compounds. Ultimately, we present thought-provoking suggestions to facilitate the future advancement of CO2 fixation technologies, harnessing the inherent capabilities of HCPs.