Optical and Photocatalytic Properties of Cobalt-Doped LuFeO(3) Powders Prepared by Oxalic Acid Assistance

B-site cobalt (Co)-doped rare-earth orthoferrites ReFeO(3) have shown considerable enhancement in physical properties compared to their parent counterparts, and Co-doped LuFeO(3) has rarely been reported. In this work, LuFe(1−x)Co(x)O(3) (x = 0, 0.05, 0.1, 0.15) powders have been successfully prepared by a mechanochemical activation-assisted solid-state reaction (MAS) method at 1100 °C for 2 h. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy studies demonstrated that a shrinkage in lattice parameters emerges when B-site Fe ions are substituted by Co ions. The morphology and elemental distribution were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The UV–visible absorbance spectra show that LuFe(0.85)Co(0.15)O(3) powders have a narrower bandgap (1.75 eV) and higher absorbance than those of LuFeO(3) (2.06 eV), obviously improving the light utilization efficiency. Additionally, LuFe(0.85)Co(0.15)O(3) powders represent a higher photocatalytic capacity than LuFeO(3) powders and can almost completely degrade MO in 5.5 h with the assistance of oxalic acid under visible irradiation. We believe that the present study will promote the application of orthorhombic LuFeO(3) in photocatalysis.