Effects of transition metal doping on electronic structure of metastable β-Fe2O3 photocatalyst for solar-to-hydrogen conversion

Abstract

Metastable β-Fe₂O₃ is a promising photocatalyst with a band gap of approximately 1.9 eV, while its intrinsic material properties remain rarely studied by theoretical calculations. Here, using density functional theory, we studied the electronic band structure and effective mass of carriers in Zr, Sn, and Ti doped β-Fe₂O₃. The calculation results show that, through the doping of Zr, Sn, or Ti, the dipole moment of FeO₆ octahedra in β-Fe₂O₃ increases, which favors the separation of photo-excited electron–hole pairs. The electron and hole effective masses in the close-packed orientation [111] in cubic β-Fe₂O₃ have the smallest absolute values. After doping with Zr, Sn, and Ti, the absolute values of electron and hole effective masses in the [111] orientation are further reduced. Furthermore, the relative ratio (D) mostly became larger after doping with Zr, Sn, and Ti, which indicates that the photoexcited carriers in the doped structure are effectively separated. Construction of Zr, Sn, and Ti doped β-Fe₂O₃ in the [111] orientation may be effective to improve the photocatalytic efficiency.