Preparation and characterization of NiO nanoparticles through calcination of malate gel

NiO nanoparticles have been successfully prepared by calcining malate gel, using basic nickel carbonate (BNC) and malic acid as the raw materials and H₂O as the solvent. The reaction was studied by TG-DTA, XRD and FT-IR. The particle size and morphology of NiO nanoparticles was characterized by TEM. The results show that nickel malate could be formed by the reaction of BNC and malic acid; the gel was composed of nickel malate and residual malic acid; the precursor can translate into NiO nanoparticles completely at 400 °C under the air, and the as-prepared sample has a cubic crystal structure with about 14 nm of average diameter by the Scherrer formula. The NiO calcined at 400 °C for 1 h was of narrow particle size distribution, weak agglomeration and small particle size. The particle size of NiO increased with the increase in temperature. Compared with other methods, the developed method is simple and the raw materials were inexpensive, so that it has the potential for further scale-up application in the industry. Furthermore, the reason for the metallic nickel formation in the course of the preparation was explained.