Applied Surface Science 390 (2016) 974–983 Contents lists available at ScienceDirect Applied Surface Science journal h om epa ge: www.elsevier.com/locate/apsusc Cu/Cu 2 O/CuO nanoparticles: Novel synthesis by exploding wire technique and extensive characterization Anshuman Sahai a,∗ , Navendu Goswami a,∗ , S.D. Kaushik b , Shilpa Tripathi c,1 a Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida 201307, India b UGC-DAE-Consortium for Scientific Research Mumbai Centre, R5 Shed, BARC, Mumbai 400085, India c UGC-DAE Consortium for Scientific Research, Indore, M.P., India a r t i c l e i n f o Article history: Received 31 May 2016 Received in revised form 30 August 2016 Accepted 3 September 2016 Available online 6 September 2016 PACS: 81.07.-b 78.30.Fs 61.05.cp 68.37.Og 78.30.-j 78.67.-n 33.60.+q Keywords: Nanoscale materials and structures: fabrication and characterization III–V and II–VI semiconductors X-ray diffraction High-resolution transmission electron microscopy (HRTEM) Infrared and Raman spectra Optical properties of low-dimensional Mesoscopic, and nanoscale materials and structures X-ray photoelectron spectra of molecules a b s t r a c t In this article, we explore potential of Exploding Wire Technique (EWT) to synthesize the copper nanopar- ticles using the copper metal in a plate and wire geometry. Rietveld refinement of X-ray diffraction (XRD) pattern of prepared material indicates presence of mixed phases of copper (Cu) and copper oxide (Cu 2 O). Agglomerates of copper and copper oxide comprised of ∼20 nm average size nanoparticles observed through high resolution transmission electron microscope (HRTEM) and energy dispersive x-ray (EDX) spectroscopy. Micro-Raman (R) and Fourier transform infrared (FTIR) spectroscopies of prepared nanoparticles reveal existence of additional minority CuO phase, not determined earlier through XRD and TEM analysis. R investigations vividly reveal cubic Cu 2 O and monoclinic CuO phases based on the difference of space group symmetries. In good agreement with Raman analysis, FTIR stretching modes corresponding to Cu 2 -O and Cu-O were also distinguished. Investigations of R and FTIR vibrational modes are in accordance and affirm concurrence of CuO phases besides predominant Cu and Cu 2 O phase. Quantum confinement effects along with increase of band gaps for direct and indirect optical transitions of Cu/Cu 2 O/CuO nanoparticles are reflected through UV–vis (UV–vis) spectroscopy. Photoluminescence (PL) spectroscopy spots the electronic levels of each phase and optical transitions processes occurring therein. Iterative X-ray photoelectron spectroscopy (XPS) fitting of core level spectra of Cu (2p 3/2 ) and O (1s), divulges presence of Cu 2+ and Cu + in the lattice with an interesting evidence of O deficiency in the lattice structure and surface adsorption. Magnetic analysis illustrates that the prepared nanomaterial demonstrates ferromagnetic behaviour at room temperature. © 2016 Elsevier B.V. All rights reserved. 1. Introduction There has been a surge in past decades to find low cost, high yield synthesis methods which lead to more productive applications [1–9]. Among the most investigated semiconducting materials, group III–V and II–VI and other metal oxides semiconductors have attracted attention of large number of researchers [1–9]. Compared with any conventional bulky material, nanomaterial possesses ∗ Corresponding author. E-mail address: navendugoswami@gmail.com (N. Goswami). 1 Present Address: Optics and Thin Film Laboratory, Bhabha Atomic Research Centre, Vishakhapatnam, A.P. 530012, India. superior or novel physio-chemical properties due to their high aspect ratio and quantum size confinement [10]. Among various nanostructures, oxide nanoparticles of copper and zinc (i.e. CuO, Cu 2 O, ZnO) have gained extensive interest of scientific community [1,4,5,11,12]. Among these, copper oxides are preferably utilized for industrial applications in magnetic devices, catalysis and solar cell [13]. Cuprous oxide (Cu 2 O) and cupric oxide (CuO) are two principal semiconductor phases of copper oxide [10,13]. Cupric Oxide, possessing a monoclinic crystal structure with indirect band gap (∼1.4-1.85 eV) is advantageous since its lower surface poten- tial barrier, as compared to metals and hence, modifies its field emission properties [10,13]. Cuprous oxide, a p-type semiconduc- tor possessing cubic structure with direct band gap of 2.2 eV, is widely applied for solar cell fabrications and catalysis [4,13]. The http://dx.doi.org/10.1016/j.apsusc.2016.09.005 0169-4332/© 2016 Elsevier B.V. All rights reserved.