Research paper The microstructure and magnetic properties of Cu/CuO/Ni core/ multi-shell nanowire arrays Feng Yang a,⇑ , Jie Shi a , Xiaofeng Zhang a , Shijie Hao a , Yinong Liu b , Chun Feng c , Lishan Cui a,⇑ a State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China b School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009, Australia c Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083, China article info Article history: Received 23 November 2017 In final form 25 February 2018 Available online 27 February 2018 Keywords: Microstructure Core/multi-shell nanowires Magnetic properties AAO template Electrodeposition abstract Multifunctional metal/oxide/metal core/multi-shell nanowire arrays were prepared mostly by physical or chemical vapor deposition. In our study, the Cu/CuO/Ni core/multi-shell nanowire arrays were prepared by AAO template-electrodeposition and oxidation processes. The Cu/Ni core/shell nanowire arrays were prepared by AAO template-electrodeposition method. The microstructure and chemical compositions of the core/multi-shell nanowires and core/shell nanowires have been characterized using transmission electron microscopy with HADDF-STEM and X-ray diffraction. Magnetization measurements revealed that the Cu/CuO/Ni and Cu/Ni nanowire arrays have high coercivity and remanence ratio. Ó 2018 Elsevier B.V. All rights reserved. 1. Introduction Core and shell nanowires have attracted one’s attention because of enhanced or new physical properties due to the presence of two or three different kinds of functional materials and the formation of heterojunctions at the interface. A lot of works about the prepa- ration of core shell nanowires have been reported. For example, R. E. Pimpinella et al [1] prepared GaAs/Fe core/shell nanowires by vapor-liquid-solid (VLS) growth process and molecular beam epi- taxy (MBE). H. W. Kim et al [2] prepared GaN/Cu core/shell nano- wires by chemical vapor deposition (CVD) and plasma sputtering method. The GaP/GaAsP/GaP core/multishell nanowires were pre- pared by gas source MBE [3]. P. Mohan et al [4] reported the growth of InP/InAs/InP core/multishell nanowire arrays by selec- tive area metalorganic vapor phase epitaxy. The Co 3 O 4 /NiO core/ shell nanowire arrays were prepared by hydrothermal synthesis method and chemical bath deposition (CBD) [5]. S. Zhang et al [6] synthesized the Cu/Ni core/shell nanowires by a hydrothermal method. Ordered Ag/Ni [7] and Cu/Ni [8] core/shell nanowire arrays were fabricated by a two-step electrodeposition process. Electrodeposition method has been proven to be a versatile approach and an inexpensive technique for the fabrication of nano- wire arrays [9]. The metal/metal core/shell nanowire arrays have been prepared by electrodeposition in the literatures. Multifunc- tional metal/oxide/metal core/multi-shell nanowire arrays were prepared mostly by physical or chemical vapor deposition. In this study, Cu/CuO/Ni core/multi-shell nanowire arrays were prepared by AAO template-electrodeposition method and oxida- tion. Cu is an ideal nonmagnetic interconnecting material for micro- and nano-electronics and is commonly used for spin devices [10–12]. CuO has been known as a semiconductor [13] and a powerful catalyst [14]. Ni as ferromagnetic element has high saturation magnetization and low crystalline anisotropy [7]. For comparison, Cu/Ni core/shell nanowire arrays were prepared by AAO template-electrodeposition method. The microstructure and magnetic properties of Cu/CuO/Ni and Cu/Ni nanowire arrays were investigated in detail. 2. Experimental procedures Commercial AAO templates with the pore diameter of 160–180 nm and the thickness of 25 mm are purchased from Hefei Pu-Yuan Nano Technology Ltd. Different metallic nanowire arrays were electrodeposited into the pores of the AAO templates using a stan- dard three-electrode system. A carbon rod was used as the counter electrode and an Ag/AgCl electrode in saturated KCl solution as the reference electrode. A 200 nm thick Ag layer was sputtered onto one side of AAO template to serve as the working electrode. The fabrication process of Cu/CuO/Ni and Cu/Ni nanowire arrays is shown schematically in Fig. S1. Cu nanowires were electrode- posited into the pores of AAO template using an electrolyte of https://doi.org/10.1016/j.cplett.2018.02.064 0009-2614/Ó 2018 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. E-mail addresses: andor_20@sina.com (F. Yang), lscui@cup.edu.cn (L. Cui). Chemical Physics Letters 697 (2018) 43–47 Contents lists available at ScienceDirect Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett