Effect of calcination temperature on the structure and hydroxylation activity of Ni0.5Cu0.5Fe2O4 nanoparticles

Nanocrystalline Ni0.5Cu0.5Fe2O4 was synthesized by sol–gel method with varying calcination temperature over the range of 500–1000. The powders obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). In addition, thermal analysis (TG–DTG–DTA) of the precursor was carried out. The study reveals the simultaneous decomposition and ferritization process at rather low temperature (280–350). For the crystalline structure investigated, single cubic spinel is gained when the precursor was decomposed at 800–1000, whereas separated crystal CuO formed when calcination temperature is below 800. The increase of calcination temperature favors the appearance of FeB3+, CuA2+ and O on the spinel surface. The hydroxylation activity is relative to the amount of CuB2+ species on the spinel surface. The lattice oxygen species on the spinel surface are favorable for the deep oxidation of phenol.