Unraveling the effects of P and S doping over g-C3N4 in strengthening Lewis basicity for CO2/glycerol conversion: A theoretical and experimental study

Abstract

Conversion of CO2 to chemicals and fuels has attracted considerable attention as CO2 is a nontoxic, non-flammable, and cheap carbon-oxygen source. However, the kinetics of CO2 conversion into other chemicals remains a challenge due to its thermodynamic stability. Herein, P and S co-doped graphitic-carbon nitride (PSCN) catalyst was synthesized through one-step thermal condensation to improve its Lewis acidity and basicity and investigate carbon dioxide/glycerol (CO2/GLY) conversion. The catalytic GLY conversion at 210 °C reached 60% and 85% using pristine g-C3N4 (CN) and PSCN, respectively, with CO2 as a carbon feedstock and CH3CN as a dehydrating agent. Density-functional theory (DFT) calculations revealed that the efficient charge transfer resulting from P and S doping could increase the catalytic activity for CO2/GLY conversion by lowering the activation barrier. This is the first study to demonstrate the catalytic activity of the PSCN catalyst for the CO2/GLY conversion and the computational work for the GLY carboxylation reaction. Moreover, the interaction site and adsorption energy were investigated for the adsorption of CO2 and GLY on PSCN and CN to elucidate the reaction mechanism. Our results demonstrated that PSCN could serve as a superior catalyst and pave new light for CO2/GLY conversion.