Direct Surface Modification of Graphitic C3N4 with Porous Organic Polymer and Silver Nanoparticles for Promoting CO2 Conversion

The development of novel heterogeneous catalysts for converting CO2 into fine chemicals under mild conditions is extremely attractive but challenging. In this study, graphitic carbon nitride modified by porous organic polymer (POP) and highly dispersed Ag nanoparticles (Ag/POP@g-C3N4) was prepared as a highly efficient heterogeneous catalyst for CO2 conversion for the first time. The POP modifying g-C3N4 remarkably increases specific surface area and nitrogen species (N-H and C=N); as a result, the abundant porous structures together with anchoring sites allow tight immobilization and homogeneous dispersion of Ag nanoparticles. Benefiting from the effective incorporation, Ag/POP@g-C3N4 exhibited superior catalytic performance for the carboxylative cyclization of propargyl alcohols with CO2 under mild conditions. From the perspective of CO2 adsorption and controlled H-1 NMR analyses, a plausible synergistic catalytic mechanism was proposed for the adsorption and activation of CO2 in combination with Ag/POP@g-C3N4 and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).