Theoretical Study of Hydrogen-Bond Interactions of CO2 in Organic Absorbent 1,3-Diphenylguanidine

Carbon capture and storage tech-nology have been rapidly devel-oped to reduce the carbon diox-ide(CO2)emission into the envi-ronment.It has been found that the amine-based organic molecules could absorb CO2 efficiently and form the bicarbonate salts through hydrogen-bond(H-bond)interactions.Recently,the aqueous 1,3-diphenylguanidine(DPG)solution was developed to trap and convert CO2 to valuable chemicals under ambient condi-tions.However,how the DPG molecules interact with CO2 in an aqueous solution remains unclear.In this work,we perform molecular dynamics simulations to explore the atom-istic details of CO2 in the aqueous DPG.The simulated results reveal that the protonated DPGH+and the bicarbonate anions prefer to form complexes through different H-bond pat-terns.These double H-bonds are quite stable in thermodynamics,as indicated from the accurate density functional theory calculations.This study is helpful to understand the catalytic mechanism of CO2 conversion in the aqueous DPG.