Synergistic Effect between CO₂ Chemisorption Using Amino-Modified Carbon Nitride and Epoxide Activation by High-Energy Electrons for Plasmon-Assisted Synthesis of Cyclic Carbonates

Photocatalytic CO 2 cycloaddition is a promising approach for CO 2 value-added processes. However, the efficiency of plasmon-assisted CO 2 cycloaddition still needs to be improved and the reaction mechanism is unclear. Herein, g-C 3 N 4 /Ag (ACN–Ag) hybrids exhibited superior activity of CO 2 cycloaddition by coupling a semiconductor into the plasmonic system, in which the ACN grafting amino group by the formation of carbon vacancies can enhance CO 2 chemisorption; meanwhile, photo-generated electrons from ACN transfer to Ag to form high-energy electrons, which can activate propylene oxide, accelerating the ring-opening step. Importantly, photo-generated electron injection from ACN to Ag and the interaction between Ag nanoparticles and ACN were confirmed by single-particle photoluminescence spectroscopy. The wavelength-dependent activity demonstrated that the plasmon excitation is crucial for the reaction. Moreover, in situ single-particle PL quenching caused by propylene oxide and in situ electron paramagnetic resonance verified the activation of propylene oxide by ACN–Ag. This work is conducive to an in-depth understanding of the mechanism of CO 2 cycloaddition at the single-particle level and provides guidance for the organic synthesis.