One-step synthesis of magnetic nickel nanostructures modified by octadecylamine using a new solvothermal reduction process

Abstract

Background: Nickel nanostructures have received considerable attention because of their potential applications in the fields of catalysis, battery materials, magnetic recording media and nickel–ceramics complex [1]. Sol-gel technique, electrochemical deposition, microwave heating, organometallic precursor pyrolysis, and chemical reduction in the liquid phase, have been applied to obtain pure metallic nickel nanostructures [2,3]. The most common procedures to prepare nickel nanostructures are the reduction of NiCl2 using reducing agents such as hydrazine, hydrogen and NaBH4 [4]. The stability of the nanostructures is commonly achieved by using diversely protective molecules (ligands) to avoid their aggregation. Methods: In this work, the thermal reduction method was applied to prepare the pure nickel nanostructures from the solution of Ni(acac)2 in DMF as both solvent and reductant in the presence of octadecylamine as a stabilizer. The morphology and structure of the synthesized products were observed by Scanning electron microscope (SEM), Powder X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), Infrared (FT-IR) and Vibrating sample magnetometer (VSM). Also, the reaction mechanism is discussed in this work. Results: The XRD pattern of synthesized nickel nanostructure, indicated the pure crystalline nickel fabricating under such conditions. The average crystalline size of the as-synthesized Ni nanostructure was calculated to be approximately 13.8 nm using Scherrer formula. The prepared sample has uniform nanoparticle morphology and the room-temperature magnetization hysteresis loop of it exhibits the typical ferromagnetic behavior of metallic Ni. Conclusion: While previous studies on the synthesis of nickel nanostructures through thermal reduction have focused on the use of a reductant, in this study, the pure nickel nanostructures were synthesized using an easy, cheap, safe and new method, without using any reducing agent. Beside, the octadecylamine acts as a protective molecule and cause to control the morphology, shape and size of nickel nanoparticles. It should be finally pointed out that the used route in this work is facile in nature, simple, comparatively cheap, and environmentally friendly.