Electron Rich Guest Regulated Enhanced CO<sub>2</sub> Reduction in a Multivariate Porous Coordination Polymer
Rohan Jena, Faruk Ahamed Rahimi, Sanchita Karmakar, Anupam Dey, Daizy Kalita, Tarak Nath Das, Tapas Kumar Maji
Abstract
Abstract The need for carbon‐neutralization technologies has prompted significant interest in developing materials for CO 2 reduction. Donor–acceptor (D–A) based flexible porous coordination polymers {[Zn(o‐phen)(ndc)].(guest)} n , (guest = anthracene = 1‐Ant , and pyrene = 1‐Pyr ) are reported as photocatalysts for CO 2 RR, yielding higher order CH 4 product. Electron‐rich anthracene (Ant) and pyrene (Pyr) guests are confined within nanopores, forming D–A charge transfer (CT) complexes with o‐phen ligand of the host. CT interaction enhances visible light absorption and modulates excitonic properties of the photocatalyst by electronic push‐pull effect (exciton binding energy 87 meV for 1‐Ant and 104 meV for 1‐Pyr ). Electron donation capability varies from Pyr to Ant, affecting catalytic properties; 1‐Ant yields 1.24 mmolg −1 of CH 4 (0.47 mmolg −1 for 1‐Pyr ) with CO as minor product. A mixed‐metal multivariate PCP {[Zn 0.55 Co 0.45 (o‐phen)(ndc)].(Ant)} n , ( 1′‐Ant ) prepared based on solid‐solution approach by substituting Zn(II) with redox‐active Co(II) enhances CH 4 production (2.79 mmolg −1 , ≈94% selectivity). D–A CT complex harvests visible light and channels electrons to Co(II) for CO 2 RR. In situ DRIFTS and theoretical studies elucidate Co(II) site's role in CO 2 binding and stabilizing reaction intermediates. This work underscores guest‐modulated electron transfer in PCPs for tailoring catalytic properties by introducing a redox‐active metal in a multivariate approach.