Highly Efficient Simultaneous Photocatalytic Reduction of CO₂ and O₂ from Air Using Conjugated Microporous Polymers with Ionic Imidazolium Sites

Efficient photocatalytic reduction of CO₂ is crucial to decrease the atmospheric concentration of CO₂. Pairing this process with H₂O₂ production is of considerable importance for simultaneously producing value-added chemicals. However, the photocatalysts reported for such a process suffer from a high recombination rate of the surface/bulk charges, as well as inefficient enrichment and activation toward CO₂ and O₂, resulting in low conversion efficiency even in the presence of organic sacrificial agents and expensive metal co-catalysts. Herein, two 1,3,5-triphenylbenzene-based organic polymers with high ionic density and porosity are prepared through a facile Sonogashira polymerization. The ionic imidazolium sites embedded in the polymeric skeleton provide the two polymers (iCMP-1 and iCMP-2) with adsorptive selectivity for CO₂/N₂ up to 98–102 at 273 K, facilitating the enrichment of CO₂ and O₂ molecules around the catalytic centers, thus boosting their catalytic conversion directly from air under solar light (100 mW cm⁻²). Benefiting from the improved charge separation and broad light absorption, along with high CO₂ and O₂ uptake, iCMP-2 can deliver excellent CO and H₂O₂ yields (611.8 and 810.6 μmol h⁻¹ g⁻¹, respectively) under an atmosphere composed of water vapor and air without any co-catalysts.