Synthesis and characterization of Ni/NiO nanochains

Ni/NiO nanochains were successfully synthesized by a facile and environmentally friendly chemical reduction method under different magnetic fields, followed by thermal oxidation at high temperatures. For the synthesis of Ni nanoparticles, hydrazine hydrate and sodium borohydride were used as reducing agents. In order to determine the size, structure, optical properties and morphology, the obtained products were characterized by X-ray diffraction (XRD), ultraviolet–visible Spectroscopy (UV–Vis), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additionally, the effect of reaction time, different magnetic field intensity and oxidation temperature on the size and morphology of synthesized nanoparticles was investigated in detail. The average size of as-prepared Ni nanoparticles in nanochain decreases with increasing magnetic force. After oxidation of samples at 600 °C, the size of NiO formed on the surface of Ni nanochains increases with increasing magnetic force. This is related to the faster oxidation of small particles due to their high surface energy. According to TEM measurements, the average diameter of Ni/NiO nanochains (synthesized at 25 mT after oxidized at 600 °C) is in the range of 97–133 nm and spherical particles are assembled in the form of a chain-like, which confirms SEM results. •Ni/NiO nanochains were successfully synthesized by chemical reduction method, followed by thermal oxidation.•After oxidation of samples at 600 °C, the size of NiO formed on the surface of Ni increases with increasing magnetic force.•According to TEM measurements, the average diameter of Ni/NiO nanochains is in the range of 97–133 nm.