Synthesis and characterization of NiO/ MgAl2O4 nanocrystals with high surface area by modified sol-gel method

Abstract

In this work, NiO/MgAl2O4 nanocrystals were prepared by modified sol–gel method and the effects of molar ratio of diethylene glycol monoethyl ether (DGME) to citric acid (2, 4, 7) and the content of nickel (5, 10, 12, 15 and 20 Wt.%) were investigated on the structural properties of nanocrystals. The prepared powders were characterized by XRD, FTIR, TGA-DSC, FESEM with the energy dispersive X-ray spectroscopy (EDX), TEM and BET. The results obtained by X-ray and BET showed that NiO/MgAl2O4 nanocrystals prepared by the modified sol-gel method have small crystal size, meso-pore structure with a high specific surface area in different amounts of nickel. The specific surface area of NiO/MgAl2O4 nanocrystals was reduced from 147 m2 g−1 to 118.4 m2 g−1 as the content of Ni increased from 5 to 20 wt %. It was observed that in the molar ratios of DGME: CA: 4, the smallest size of crystalline NiO and MgAl2O4 phase was estimated about 12.5 nm and 13.5 nm, respectively. Also, The results from FESEM showed that the morphology of surface NiO/MgAl2O4 powders with 20 wt %Ni in molar ratios of DGME: CA: 2, 4 and 7 were spherical, cubic and sponge, respectively. Furthermore, the results from TEM showed that NiO/MgAl2O4 powders with 15 wt %Ni and in molar ratios of DGME: CA: 4 had nanometric particles about 10 nm, polycrystalline and mesopores structure.