Effective CO2 Catalytic Conversion by Nitrogen-Rich Covalent Organic Framework-Immobilized Ag Nanoparticles

Taking carbon dioxide (CO2) as a significant C1 source and converting it into value-added chemicals presents a promising strategy for addressing the energy and environmental issues arising from excessive anthropogenic emissions. Nevertheless, catalytic CO2 conversion, particularly under moderate conditions, remains a formidable challenge. Herein, a composite of Aza-COF-immobilized silver nano particles (Ag NPs), Ag/Aza-COF, was successfully fabricated by taking the nitrogen-rich COF, Aza-COF, as the porous carrier. Catalytic experiments revealed that with the presence of Ag/Aza-COF, 100% conversion of 2-methylbut-3-yn-2-ol to the corresponding alkylene cyclic carbonate was achieved after 9 h of reaction at ambient temperature and pressure using CH3CN as the solvent. Further studies revealed that the Ag/Aza-COF exhibits very high catalytic activity and effective recyclability in CO2 fixation with alkynyl alcohol and alkynyl amine at moderate conditions, surpassing the performance of surfactant-protected Ag NPs. X-ray photoelectron spectroscopy and Raman spectral analyses elucidated that strong interactions resulting from the coordination between the nitrogen atoms in the Aza-COF and Ag atoms in Ag NPs prevents their further aggregation and thereby preserving the high activity and recyclability of the composite. This finding demonstrates that the judicious selection of appropriate porous materials to restrict the aggregation of metal particles can yield efficient nanocatalyst composites.