Investigation of the structure and surface characteristics of Cu-Ni-M(III) mixed oxides (M = Al, Cr and In) prepared from layered double hydroxide precursors

The Cu-Ni-M(III) mixed oxides (M = Al, Cr and In) were prepared by calcination of layered double hydroxide precursors with Cu2+/Ni2+/M3+ ratio of 1/2/1. The materials were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and low temperature N2 adsorption-desorption experiments. The results indicated that calcination of precursors at 500 °C gave rise to mixed metal oxides including simple oxides and composite oxides, and the composition distributions of obtained oxides depended on the nature of trivalent cation in precursors. Under mild experimental conditions (atmospheric pressure and 25 °C), oxidation of aqueous phenol solutions by hydrogen peroxide exhibited that the Cr-containing mixed oxide achieved the highest conversion of phenol owing to the presence of more amount of composite oxide phase containing active copper centers, while the aluminum-containing one could significantly enhance deep oxidation of phenol into smaller molecules owing to the presence of more surface oxygen species.