A Porous Supramolecular Organic Framework for Direct CO₂ Capture and Photocatalytic Reduction From Air

Supramolecular organic frameworks (SOFs) with intrinsic porosity and appealing optoelectronic properties hold promise for the integrated capture and photocatalytic conversion of CO₂ from the air. Unfortunately, SOFs that can efficiently reduce CO₂ have never been reported so far. In this work, we demonstrate the construction of a porous SOF through host-guest binding between cucurbit[8]uril (CB[8]) and a tetraphenylethylene-based derivative for highly selective CO₂ reduction in the atmosphere of water vapor and air under solar light. The abundant cationic nitrogen sites within the framework endow the SOF with a CO₂ uptake capacity of 14.41 cm³ g^-1 at 298 K and 1 bar. Initial slope selectivity calculations demonstrated that SOF possessed high separation capability of CO₂ over N₂ with selectivity up to 57 at 273 K. In addition, the SOF showed efficient light harvesting in the visible region with an optical gap of 2.19 eV. Benefitting from these unique features, the SOF catalyzed the reduction of CO₂ with a stable CO production rate of 69.78 μmol h^-1 g^-1. This research paves the way to design porous SOF-based photocatalysts for biomimetic reduction of CO₂ in a practical environment.