CO2 Fixation via epoxide cycloaddition with a highly active and stable MOF-808/GO composite catalyst

Abstract

The CO2 cycloaddition reaction effectively mitigates the greenhouse effect while producing high-value cyclic carbonates. Metal-organic frameworks (MOFs) have shown promise for CO2 cycloaddition with epoxides; however, the aggregation of MOFs due to high surface energy hinders mass transfer and catalytic performance. By pre-coordinating graphene oxide (GO) to regulate the dispersion of MOF-808, the resulting MOF-808/GO-100 composite catalyst exhibits twice the activity of pristine MOF-808, achieving 92.6% conversion of epichlorohydrin (ECH) with 98.2% selectivity to ECH carbonate without adding any co-catalysts. The incorporation of GO introduces numerous hydroxyl groups on the catalyst surface, serving as hydrogen bonding donors. The oxygen-containing groups on GO can compete with ligands for Zr coordination, generating defective Zr sites. The synergistic effect between defective Zr sites and hydrogen bonding donors collectively promotes epoxide opening. Notably, GO correspondingly enhances the dispersion of MOF-808 and induces mesopore formation through its stacking effect at the interface with MOF-808. Across various epoxide cycloaddition reactions, MOF-808/GO-100 consistently demonstrated optimal performance and maintained high stability over multiple reaction cycles.