Synthesis of Fe2O3–NiO–Cr2O3 composites from NiFe-layered double hydroxide for degrading methylene blue under visible light

Abstract To develop a low-cost and highly efficient photocatalyst under the visible illumination, Ni 3 Fe–CO 3 –LDH (referred to hereafter as NiFe-layered double hydroxide or NiFe–LDH) was used as a precursor to synthesize Fe 2 O 3 –NiO–Cr 2 O 3 composite. The NiFe–LDH was prepared by co-precipitation and then it was exchanged with dichromate. After calcining at 600 °C, the Fe 2 O 3 –NiO–Cr 2 O 3 composite was obtained. The composites' absorption edge intensely extended up to ca. 700 nm covering the full visible light spectrum and showed high catalytic activity at natural pH under the visible light illumination. A very high methylene blue degradation of 91.2% was achieved with the aid of H 2 O 2 in 120 min with no detectable Cr in solution.