| Progress of largely selective and sensitive compounds is essential for removing two toxic gases of hydrogen sulfide (H2S) and sulfur dioxide (SO2).The effect of Iron (Fe), Nickel (Ni), and Zinc (Zn) doping of graphene (Gr) nanosheet (NS) on their adsorption for both H2S and SO2 gases has been investigated in this work using first-principles density-functional theory (DFT) computations. In this research, it has been investigated the ability of transition metals of iron, nickel, and zinc doping of Gr@NS for adsorption toxic gas of Sulfur Dioxide and Hydrogen Sulfide Removal. The Langmuir adsorption model with a three-layered ONIOM used CAM-B3LYP functional accompanying LANL2DZ and 6--31 + G (d,p) basis sets due to Gaussian 16 revision C.01 program on the complexes of H2S and SO2 → TM(Fe, Ni, Zn) doping of Gr nanosheet. The changes of charge density have shown the values of ∆Q Fe-doped = − 0.566 >> ∆Q Zn-doped = + 0.387 >>> ∆Q Ni-doped = + 0.605 for H2S adsorption and ∆Q Fe-doped = − 0.336 >> ∆Q Zn-doped = + 0.376 >>> ∆Q Ni-doped = + 0.618 for SO2 adsorption. Based on these amount of changes of charge density, H2S and SO2 have exhibited a significant charge transfer for Fe doping of graphene nanosheet compared to Ni- and Zn-doped Gr@NS. Based on NMR spectroscopy, it has been illustrated that the sharp peaks in the adsorption site are due to the Fe, Ni, and Zn doping on the surface of graphene nanosheet through H2S and SO2 adsorption. However, it has represented some fluctuations in the chemical shielding of isotropic and anisotropy behaviors around Zn-doped on the H2S/ SO2 → Zn-doped/Gr@NS. Moreover, it has exhibited the fluctuation of occupancy of NBO for H2S/SO2 → Fe-doped, H2S/SO2 → Ni-doped, and H2S/SO2 → Zn-doped graphene nanosheet through the Langmuir adsorption process by indicating the active sulfur atom in hydrogen sulfide (H2S) and sulfur dioxide (SO2) becoming close to the nanosheet. The amounts of ΔGadso through IR computations based on polarizability have exhibited that ΔGads,SO2→Fe-Co and ΔGads,H2S→Fe-Co have exhibited the most energy gap because of charge density transfer from sulfur atom in hydrogen sulfide (H2S) and sulfur dioxide (SO2) to Fe doping of Gr@NS, although, ΔGH2S/SO2→Zn-C0 > ΔGH2S/SO2→Ni-C0 > ΔGH2S/SO2→Fe-C0 . Frontier molecular orbitals of HOMO, LUMO, and band energy gap accompanying some chemical reactivity parameters have represented the attributes of molecular electrical transport of TM (Fe, Ni, Zn) doping of Gr nanosheet for adsorption of H2S and SO2 gases. Our results have provided a favorable understanding of the interaction between TM doping of Gr@NS nanosheet and H2S and SO2 molecules. A high performance of TM doping of Gr@NS as gas sensor is demonstrated by modeling the material's transport characteristics by means of the Langmuir adsorption and three-layered ONIOM/DFT method. Furthermore, the results of partial electron density of states (PDOS) have confirmed an obvious charge accumulation between the graphene nanosheet and doped atoms of Fe, Ni, and Zn through adsorption of H2S and SO2 molecules on the surface due to the recognition of the conduction band region. Finally, this research can build up our knowledge about the electronic structure, relative stability, and surface bonding of various metal-doped graphene nanosheets, metal alloy surfaces, and other dependent mechanisms, like heterogeneous catalysis, friction lubrication, and biological systems. |
Dr. Öğr. Üyesi Fatemeh MOLLAAMIN
Majid Monajjemi
