Application of a facile solid-state process to synthesize the CdO spherical nanoparticles

Mechanochemical process has attracted a worldwide interest in the synthesis of nanomaterials since reactions can be run in solid state without any organic solvent. Therefore, this method is an environmentally friendly reaction. Cadmium oxide is a category of the practical semiconductor metal oxides, which is widely applied in various scientific and industrial fields because of its catalytic, optical, and electrical properties. In this study, cadmium oxide spherical nanoparticles were successfully synthesized using a facile and effective solid-state process called mechanochemical reaction. This performance was carried out by employing cadmium acetate dihydrate and urea as reactants without any additives at room temperature and an adjusted rate of 30 Hz (1,800 rpm) for 130 min. Due to calcination of the resulting precursor at 500°C for 2 h in a furnace, the organic sections disappeared and only the CdO phase remained. The X-ray diffraction pattern confirmed the formation of the CdO phase with an excellent crystalline structure. Scanning electron microscopy and transmission electron microscopy images indicated that the morphology of the product is spherical nanoparticles with an average particle size of 46 nm and a standard deviation of 1.95. Particle size distribution was concluded using a statistical method and image processing program. Meanwhile, the solid-state diffuse reflectance spectrum of the resulting product was evaluated to study its optical property via measurement of the band gap energy value (Eg).