First-principles study of sulfur atom doping and adsorption on α–Fe2O3 (0001) film

Abstract

Using the spin-polarized density functional theory (DFT) and the DFT + U method, the geometric and electronic properties of the hematite α-Fe 2 O 3 (0001) film with the sulfur (S) atom doping and adsorption have been investigated systematically.The most stable hematite α-Fe 2 O 3 (0001) film with an anti-ferromagnetic arrangement is identified. For the study of sulfur adsorption on the film, the S adatom prefers to bond with three O atoms, in the center of a triangle formed by the three O atoms. The S acts as a cation at this site. The sulfur adsorption has introduced two gap states, in addition to the unoccupied surface states. Furthermore, with the most stable S-adsorption configuration, the diffusion of the S adatom from the surface to the inside is searched and the transition state along the minimum-energy pathway is also evaluated. For S-doping in the film, it is found that S substitution of O in the top layer is energetically favored than that in the deeper layer. It shows that the value of the band gap is reduced to ~1.26eV from ~1.43eV of the clean film. The formation energy of S substitution of O in the film is also obtained.

Microwave synthesis of sulfur‐doped α‐Fe2O3 and testing in photodegradation of methyl orange

“…It is known that the top of the valance band (VB) is dominated by O 2p, and the Fe 3d orbital dominates the bottom of CB, which was proved by theoretical calculations the density functional theory method. When α‐Fe 2 O 3 is doped using sulfur as a dopant, the 3p orbital of sulfur interacts with O 2p orbitals, resulting in broadening of VB, therefore shortening the band gap of the photocatalyst 47 . In addition, the preparation method and the conditions of the procedure are important for the incorporation of sulfur into the lattice of semiconductors.…”

“…When α-Fe 2 O 3 is doped using sulfur as a dopant, the 3p orbital of sulfur interacts with O 2p orbitals, resulting in broadening of VB, therefore shortening the band gap of the photocatalyst. 47 In addition, the preparation method and the conditions of the procedure are important for the incorporation of sulfur into the lattice of semiconductors. Nonmetal dopants can be in substitutional or interstitial sites, which means that the energy states of these dopants might broaden the VB or be located between VB and CB.…”

Transferable Gaussian Attractive Potentials for Organic/Oxide Interfaces

“…During the self-consistent field process (SCF), the energies were converged to 10 −6 Ha. As hematite is an antiferromagnetic oxide, 36,80 we used the spinpolarized formalism to describe the anti-ferromagnetic electronic structure and applied the DFT + U method with the (U-J) set to 5 eV to take into account the strong electronic correlation of the iron 3d electrons. 36 The bulk structures of hematite and γ-alumina were optimized to forces below 4.5 × 10 −4 Ha/bohr.…”

(Dis)Similarities of adsorption of diverse functional groups over alumina and hematite depending on the surface state

“…The solvation of the studied molecules in the industrial oil can be neglected compared with the strength of adsorption. 20 For hematite, which is an antiferromagnetic oxide 45,46 , we applied the DFT+U method 47 to account for the strong electronic correlation of Fe localized 3d electrons. This method, relying on the combination of DFT with a Hubbard-Hamiltonian 48 in order to explicitly consider the Coulombic repulsion, has shown to be useful to achieve agreement with experimental values of different properties of hematite [49][50][51][52] and it is widely used in theoretical studies of adsorption of different species over hematite [53][54][55][56] .…”