Contents lists available at ScienceDirect Journal of Physics and Chemistry of Solids journal homepage: www.elsevier.com/locate/jpcs Synthesis, structural, optical and photocatalytic properties of CdS/ZnS core/shell nanoparticles Ch.Venkata Reddy a , Jaesool Shim a, ⁎ , Migyung Cho b, ⁎ a School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea b Department of Game Engineering, Tongmyong University, Busan 608-711, South Korea ARTICLE INFO Keywords: CdS/ZnS core/shell Nanoparticles Band gap Photocatalytic activity ABSTRACT CdS, ZnS and CdS/ZnS core/shell nanoparticles were successfully synthesized via two-step synthesis method. The as-prepared CdS, ZnS and CdS/ZnS core/shell nanoparticles were used to study the structural, morphological, and optical properties by PXRD, TEM, HRTEM, UV–vis spectroscopy, N 2 adsorption- desorption, FT-IR, PL and Raman spectroscopy measurements. The XRD pattern confirms the crystal structure of the prepared ZnS, CdS, and CdS/ZnS core/shell nanoparticles. The crystallinity of the as-prepared samples is confirmed by PXRD, TEM and HRTEM analysis. The BET analysis showed that the CdS/ZnS core/shell nanoparticles had larger surface area and pore diameter than CdS and ZnS. The Raman and FT-IR spectra confirm the fundamental vibrational modes of CdS and ZnS respectively. Compared to pure CdS and ZnS, CdS/ ZnS core/shell nanoparticles exhibited higher photocatalytic activity for the degradation of methyl orange (MO). The enhancement of photocatalytic activity in the CdS/ZnS core/shell nanoparticles is due to the interface actions between CdS and ZnS, which greatly reduces the recombination of photogenerated electrons-holes pair. The proposed mechanism for degradation of MO dye is discussed in detail. 1. Introduction Nanostructures have been generated great interest in both funda- mental studies and technical applications because of their unique and superior optical and electronic properties. Semiconductor nanoparti- cles have recently established to be a kind of effective material for photocatalytic, photovoltaic and biomedical applications due to their unique properties [1,2]. The growth of protective shell on the core of nanoparticles has demonstrated to be an effective solution to eliminate the surface defects by reducing the number of dangling bonds on surface and improve the photo stability by physically separating the core surface from its surrounding medium [1,3]. The optical properties of various semiconductor cab be enhanced by coating them with a shell of a second higher band gap semiconductor [4]. Because of its potential applications, CdS/ZnS core/shell nanoparticles is an interesting one and furthermore both Cadmium Sulfide (CdS) and Zinc Sulfide (ZnS) have similar crystalline structures. Furthermore, ZnS has higher band gap energy than CdS. Owing to its higher band gap energy of ZnS, it is extensively used as surface passivating shell material for CdS [5]. Several reports have been reported on CdS/ZnS core/shell nanos- tructures. The modified solvothermal synthesis of CdS/ZnS core/shell nanorods for optoelectronic applications has been reported by suganthi et.al [6]. Petr et.al reported on molecular modeling of CdS/ZnS core/ shell nanoparticles and its photocatalytic decomposition of Methylene Blue [7]. Removal of heavy metal ions using CdS/ZnS nanoparticles by sonochemical synthesis was reported [3]. For the enhanced optical, surface and photoluminescence properties of CdS/ZnS quantum dots were reported [8,9]. Water soluble fluorescent l-cysteine capped CdS/ ZnS core–shell has been developed for optical sensors [10]. Qutub et.al reported on synthesized CdS/ZnS and ZnS/CdS core/shell and sand- wich nano composites for photocatalytic properties [4]. The optical properties are strongly depends on the size and the surface quality the nanoparticles, which can be enhanced by passivating the bare surface with a suitable shell material [3,11]. For better control over shape and size distribution of core/shell chalcogenide nanoparticles, several preparation methods were reported like sol gel, chemical precipitation, micro emulsion and inverse micelles. Pure CdS, ZnS and CdS/ZnS core/shell nanoparticles are prepared using two-step method. The as-synthesized semiconductors are used to characterize by means of XRD, TEM, HRTEM, Surface analysis, Raman, Photoluminescence, FT-IR, and optical absorption measurements. The as-prepared semiconducting materials are used for photocatalytic prop- erties. The hetero structured catalyst is shown as a visible light driven photocatalyst with a much improved photo reactivity and photo stability. http://dx.doi.org/10.1016/j.jpcs.2016.12.011 Received 29 June 2016; Received in revised form 24 August 2016; Accepted 12 December 2016 ⁎ Corresponding authors. E-mail addresses: jshim@ynu.ac.kr (J. Shim), mgcho@tu.ac.kr (M. Cho). Journal of Physics and Chemistry of Solids 103 (2017) 209–217 Available online 16 December 2016 0022-3697/ © 2016 Published by Elsevier Ltd. MARK