Vietnam Journal of Science and Technology 57 (3A) (2019) 21-28 doi:10.15625/2525-2518/57/3A/13945 EFFECTS OF SYNTHESIS CONDITIONS ON STRUCTURE OF NICKEL NANOWIRES PREPARED BY REDUCTION METHOD Nguyen Truong Xuan Minh 1 , Bui Thi Minh Thu 1 , Le Thi Cuc 1 , Nguyen Huu Linh 1 , Pham Ngoc Y 1 , Huynh Ky Phuong Ha 1, 2 , Nguyen Truong Son 1, 2, * 1 Faculty of Chemical Engineering, Ho Chi Minh City University of Technology, VNU-HCM, 268 Ly Thuong Kiet St., Dist. 10, Ho Chi Minh City 2 Research Institute for Sustainable Energy, Ho Chi Minh City University of Technology, VNU-HCM, 268 Ly Thuong Kiet St., Dist. 10, Ho Chi Minh City * Email: ntson@hcmut.edu.vn Received: 13 July 2019; Accepted for publication: 21 September 2019 Abstract. Nickel nanostructures prepared by various methods have received considerable attentions due to their numerous applications. In this study, one-dimensional nickel nanowires (NiNWs) were synthesized by the reduction of nickel (II) chloride in polyol medium. Polyvinylpyrrolidone (PVP) served as the surfactant and hydrazine hydrate was used as the reductant. The effects of different experimental parameters, i.e. concentration of Ni 2+ , volume of N 2 H 4 , concentration of PVP and reaction temperature on the formation and morphology of NiNWs were studied. The structure, composition and surface morphology of the materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the morphology as well as the diameter of NiNWs could be effectively controlled by adjusting parameters of the synthesis process. Keywords: nickel, one-dimensional, nanowire, morphology control, polyol method. Classification numbers: 2.4.2, 2.10.2. 1. INTRODUCTION Nanomaterials have, by definition, one or more dimension in the nanometer scale (≤100 nm) range and subsequently show novel properties from their bulk materials [1]. The synthesis, characterization, and applications of nanoparticles are among the most important sections of the wide range of nanotechnology areas falling under the general “nanotechnology” umbrella. In recent years, nanoparticles have been the center of attention of researchers in the field as the transition from microparticles to nanoparticles was seen to lead to immense changes in the physical and chemical properties of a material [2]. Nickel nanorods with a diameter of 8–10 nm and length of 100–200 nm had been successfully prepared by the reduction of nickel chloride (NiCl 2 ) with hydrazine hydrate in water/ butanol/potassium oleate/kerosene microemulsion [3]. Synthesis of nanowires in the aqueous phase is the preferred approach as it is non-flammable, cheap, environmental friendly, safe and feasible for large scale production [4]. Nickel nanowires