Nano-size MZnAl (M = Cu, Co, Ni) metal oxides obtained by combining hydrothermal synthesis with urea homogeneous precipitation procedures

The well-crystallized MZnAl (M = Cu, Co, Ni) layered-double hydroxides (LDHs) were synthesized by combining hydrothermal synthesis with urea homogeneous processes. The LDH precursors were calcined at 450 °C to obtain the nanoscale mixed metal oxides. Characterization techniques including XRD, TG–DTG, TPR, N2 adsorption/desorption, HRTEM and SEM were carried out to investigate the LDH precursors, thermal decomposition behavior and reducibility, porosity and morphology of the calcined samples. For the LDHs containing Cu, the thermal decomposition process became more complex because of its Jahn–Teller effect, and the phases of the calcined samples were different as a result of preparation conditions. Hydrothermal synthesis led to easy generation of the spinel phase at lower thermal treatment temperature (450 °C). Further, the reducibility and texture properties were influenced.