Nitrogen-doped Fullerenes for CO2 Capture: A DFT Study

Abstract

The structural and electronic properties of several nitrogen-doped fullerenes, C60−2nN2n (n = 1–12), have been studied using density functional theory (DFT) at the M06L/6-311+G(d)//M06L/6-31G(d) level. The electronic features studied using a molecular electrostatic potential (MESP) topology analysis revealed that increasing the N-doping leads to a large improvement in the electron density of the carbon cage. As a result, the N-doped fullerenes showed a stronger interaction with CO2 molecules than C60. Also, the formation of large clusters of CO2 around the N-doped C60 is modeled which revealed that the interaction energy per CO2 is better than the interaction of a single CO2 with the same system. The improved interaction of CO2 in the cluster is attributed to the positive cooperative interaction arising between the adsorbed CO2 molecules. The study also examined the MESP features and the CO2 binding affinity of the anionic modification of the N-doped C60 by attaching a CN− unit on a carbon center. Compared to the N-doped C60, the highly electron-rich anion (C60−2nN2nCN)− showed improved affinity to CO2. The superior electronic features and CO2 binding energy data of N-fullerenes and N-cyanofullerides suggest that they are potent CO2 capturing agents.