Effect of boron-doping and electric field on CO₂ adsorption on C₆₀ fullerene. A DFT study

To improve the efficiency of CO₂ adsorption in buckminsterfullerene (C₆₀) is necessary to better understand and tune its properties. Replacing a carbon atom by a heteroatom with a strong Lewis acidity inside the pristine C₆₀ fullerene or applying an electric field can cause the nanostructure to become a high-performance CO₂ sorbent. In this theoretical study C₆₀ was doped by single boron atom to generate a fullerene (referred to as C₅₉B). Minimum energies (the most stable 3D arrangement of the molecules) of C₆₀-CO₂ and C₅₉B-CO₂ systems were optimized using density functional theory (DFT) calculations to determine the adsorption energy and evaluate its stability. The influence of an external electric field (imposed in the direction of the axis passing through fullerene C₆₀ or C₅₉B and CO₂ in the range of 0.001 and 0.020 au) in the CO₂ adsorption on C₆₀ and C₅₉B was also studied. The adsorption energies of CO₂ on C₆₀ and C₅₉B fullerenes were -0.14 and -0.21 eV respectively, revealing the effect of the heteroatom dopant on the C₅₉B with increasing adsorption energy. When applying an electric field of 0.011 au in C₆₀-CO₂ and in C₅₉B-CO₂, the result was an adsorption energy of -0.3 and -1.2 eV, respectively: providing higher performance for the C₅₉B-CO₂ by increasing further the adsorption energy in this doped fullerene. Also, according to these results, the C-C bond formed between the CO₂ and the C₅₉B fullerene applying electric field is covalent (1.7 Å), which results in chemisorption. Additionally, the structural and electronic properties were studied, such as the dipole moment, electrostatic potential surfaces, the HOMO-LUMO gaps, the infrared (IR) spectrums were calculated to validate the stability of the molecular structures, and density of states (DOS) analysis to confirm the CO₂ adsorption on C₆₀ and on C₅₉B and understand their interaction mechanism for possible applications such as CO₂ gas sensing or environmental remediation.

The geometry optimization and electronic properties calculations based on DFT were performed using ORCA software package. The computational parameters included the general gradient approximation functional PBE with 6-31G(d,p) basis set, combined with dispersion correction developed by Grimme DFT-D3 approach dispersion correction D3BJ and basis set superposition error (BSSE).