Tailoring morphology, enhancing magnetization and photocatalytic activity via Cr doping in Bi25FeO40

The Cr doped Bi25FeO40 (Bi25Fe1-xCrxO40, x = 0-0.5) powders were synthesized by a simple hydrothermal process. Effects of the Cr dopant on the crystalline structure, morphologies, optical properties and photocatalytic activities of Bi25FeO40 have been investigated. With the increase of Cr concentration, the shape of particles occurs to transformation from regular microcubes (x = 0) to microspheres (x = 0.3) owing to the lattice expansion. The Fe-O and Cr-O bonds can be coexistence and Fe3+ cation could be well replaced by the Cr3+ without any secondary phases for the Bi25Fe1-xCrxO40 (x ≤ 0.3). Due to the enhanced exchange interaction between Fe2p-O-Cr2p, the decreased optical band gaps and enhancement of magnetization were found. The photo-degradation efficiency for 120 min was significantly enhanced from 43.8% (pure Bi25FeO40) to 92.5% (Bi25Fe0.75Cr0.25O40), which is nearly 2.1-fold higher than that of undoped Bi25FeO40 powders, attributing to cooperative effects of the different morphologies and energy band configurations.