Computational Study on Effect of Transition Metal (Mn and Fe) Doping on Structural, Electronic and Magnetic Properties of Hexagonal-Tungsten Trioxide (Hex-WO3)

Abstract

Over a decade it has been proved that electron doping and electron-phonon coupling play a vital role in controlling the wide band gap issues of some transition metal oxide within density functional theory. However, electron doping and electron-phonon mechanism alone cannot give an excellent description of the performance of photocatalytic in Hex-WO₃. In this study, we systematically investigate the effect of Single atom transition metal doping and introduce the Hubbard  correction. The electronic structure calculations on both Hex-WO₃ and A_ϰW_1–ϰO₃ (A=Mn, Fe) using density functional theory with Hubbard  (DFT+) were carried out. We have found that presence of U=5.8eV for W in optimizing pure Hex-WO₃ produced a stable structure only with overestimation in crystal parameters, while the presence of Mn and Fe Impurities, as well as Hubbard correction (U=4.6eV for Mn and U=3.8eV for Fe)  produced a stable structure with high anisotropic distortion in the lattice parameters and negative formation energies of about -1.992 eV and -1.651 eV for Mn and Fe doping respectively, while for the electronic properties, the present of  shows that Hex-WO₃ is direct wide gap material with a gap of about 2.7eV which is also an overestimation. But the presence of Mn and Fe impurities shrink the band gap and changes the band edge from nonmagnetic WO₃ to A_ϰW_1–ϰO₃ (A=Mn, and Fe) ferromagnetism with 2.7 µB and antiferromagnetic with 1.815µB magnetic moment per defect in case of Mn and Fe doping respectively, indicating that Mn_ϰW_{1 – ϰ}O₃ can be a suitable material for magnetic water splitting.