Atomically dispersed metal-incorporated, moldable heterogeneous catalyst with coordination geometry-verified ligands for the synthesis of cyclic carbonates from carbon dioxide.

The cycloaddition of carbon dioxide to epoxides under mild conditions is an attractive route for carbon dioxide utilization, but practical catalyst design requires a balance between activity, catalyst recovery, and long-term stability. Herein, we report a moldable zinc-incorporated polyurethane (Zn-PU) prepared by one-step gelation of phenylene diisocyanate, triethanolamine, and zinc acetate, followed by direct drying. Electrospray ionization mass spectrometry of precursor solutions, together with nuclear magnetic resonance analysis of a model urethane-forming reaction, supports ligand exchange between triethanolamine and metal precursors before polymer network formation. X-ray diffraction, selected-area electron diffraction, high-angle annular dark-field scanning transmission electron microscopy, and elemental mapping indicate an amorphous polyurethane matrix containing highly dispersed zinc species. In the presence of tetrabutylammonium bromide (TBAB, 3.60 mol% relative to epoxide) as a homogeneous nucleophilic co-catalyst, Zn-PU acts as a recoverable Lewis-acidic component for the cycloaddition of carbon dioxide with epoxides, achieving high conversion and selectivity at 1 bar carbon dioxide and 50 °C. Over one consecutive 60-cycle recycling test, the Zn-PU/TBAB binary system reached a high cumulative turnover number (C-TON) of 3,530,750 based on Zn, which is reported as a recycling-based lifetime metric. In situ Fourier transform infrared spectroscopy suggests reversible carbon dioxide enrichment in the polar polyurethane environment.