Synergistic Dual-Active Sites Engineering in ZIF-Derived CoOx/B-Modified g-C3N4 for Efficient CO2 Cycloaddition Under Mild Conditions

Graphical CoO x /BCN catalyst with dual active sites was successfully synthesized. This catalyst exhibits excellent selectivity (99%) and a cyclic carbonate yield (98%) in the CO 2 cycloaddition reaction with the nucleophilic reagent KI under solvent-free and mild reaction conditions. This catalyst also has good stability and reusability, providing a new direction for the design of high-performance CO 2 cycloaddition catalysts. The carbon dioxide (CO 2 ) cycloaddition reaction provides an efficient route to achieve resource utilization of CO 2 . However, the inherent chemical stability of CO 2 itself hinders its efficient transformation into cyclic carbonates. Herein, the CoO x /BCN catalyst was successfully prepared by a simple deposition method. The CoO x /BCN exhibited excellent catalytic performance in the CO 2 cycloaddition reaction synergistically catalyzed with the nucleophilic reagent KI under solvent-free and mild reaction conditions (80 °C, 0.8 MPa, 6 h). The yield of cyclic carbonate was 98% and the selectivity was 99%, which was significantly superior to CoO x /CN catalyst (with a cyclic carbonate yield of 73.7%). Furthermore, after six cyclic reactions, CoO x /BCN still maintained a yield of over 93%. It was found that after boron (B) was doped into graphitic carbon nitride (g-C 3 N 4 ), the generated ─NB(OH) 2 group on CoO x /BCN effectively activated the epoxide. Importantly, the interaction between B-doped g-C 3 N 4 and CoO x induced the generation of abundant oxygen vacancies, which provided sufficient active sites for CO 2 adsorption and activation. In addition, carbonates were identified as the main reaction intermediates by in situ DRIFTS, and the possible reaction pathways of the CoO x /BCN catalyst were proposed. Therefore, this work provides new idea for the design of catalysts for CO 2 cycloaddition.