First-Principle Study on Heterofullerenes: Effective and Multifunctional in Hg Removal

Mercury control is very important with regard to the clean use of fossil fuels. Although both carbonaceous materials and metals can effectively remove Hg-0, they still face great challenges. Single-atom loaded materials provide new ways for Hg species removal. Metal-substituted C60 has been predicted to have high chemical reactivity. Accordingly, the adsorption mechanisms of Hg species on 19 types of heterofullerenes (C59M, M = Ti, V, Mn, Fe, Co, Ni, Zn, Zr, Nb, Mo, Tc, Ru, Rh, Pd Cu, Au, W, Ir, and Ag) were studied by using DFT method. Most of the C59M can strongly adsorb Hg-0, and C59Cu is the best one, with its adsorption energy being -0.67 eV. C59M' (M' = Fe, Co, Ni, Cu, Zn, and Mn) with strong interaction with He were chosen for further studying on their adsorption of HgCl and HgCl2. Both HgCI and HgCl2 prefer dissociative adsorption. Moreover, He adsorption on C59M'Cl and CS9M'Cl-2 were checked. The results showed that He physically adsorbs on both C59M'CI and C59M'Cl-2. Importantly, oxidative adsorption of He were also calculated on C59M'Cl-2. C59CoCl(2) shows excellent removal ability for Hg-0 via oxidative adsorption due to the lowest activation barrier (0.89 eV), then C59CuCl(2) has the next-lowest barrier (1.00 eV). This study is of great significance for understanding the adsorption mechanisms and expands the theoretical system of carbon-based materials for Hg species removal.