Preparation and characterization of host (mesoporous aluminosilicate material)–guest (semiconductor nanoparticles) nanocomposite materials A. Pourahmad a,c, ⁎ , Sh. Sohrabnezhad b , M.S. Sadjadi c , K. Zare c a Department of Chemistry, Faculty of Science, Islamic Azad University, Rasht Branch, Rasht, Iran b Department of Chemistry, Faculty of Science, University of Mohaghegh Ardebili, Ardebil, Iran c Department of Chemistry, Science and Research Campus, Islamic Azad University, Poonak, Tehran, Iran Received 10 February 2007; accepted 13 June 2007 Available online 15 June 2007 Abstract We report the optical and structural properties of NiS and CoS nanoparticles in AlMCM-41 zeolite. The samples were obtained by sulfidation of the Ni 2+ and Co 2+ ion exchange zeolite in a Na 2 S solution at room temperature. The optical properties of the samples were studied by UV–Vis spectroscopy. Their crystalline structure and morphology were studied by XRD and scanning electron microscopy (SEM). The results show that the nanoparticles grow outside the mesopore AlMCM-41 matrix. Exciton absorption peaks at higher energy than the fundamental absorption edge of bulk NiS and CoS indicate quantum confinement effects in nanoparticles as a consequence of their small size. The absorption spectra show that the optical band gap varies in the range 3.53–4.47 eV. © 2007 Elsevier B.V. All rights reserved. Keywords: AlMCM-41; Nanocomposites; Nanoparticles; Semiconductors; UV–Visible spectroscopy; Zeolite 1. Introduction Since the discovery of buckminsterfullerene [1], nanostruc- tured materials have attracted great interest due to their potential impact in many areas such as electronics, photonics, catalysis, and sensing [2,3]. Many applications are possible including one-dimensional superconductors, high-density semiconductor nanowire sensor arrays, gigahertz nanomechanical resonators, and high-density molecular electronics circuits [4,5]. In 1992, the synthesis of a new family of nanoporous molecular sieves designated as M41S was reported [6]. MCM-41, one member of this family, has uniform cylindrical pores in hexagonal arrangement and is produced using rod-like micelles of cationic surfactant molecules as a template. The main characteristics of MCM-41 are its high pore volume (∼ 1 cm 3 g - 1 ), large surface area (∼ 1000 m 2 g - 1 ) and very narrow pore-size distribution (2–10 nm). Due to the regularly hexagonal arrays of nanoporous channels and changeable pore diameters, MCM- 41 has become the particular focus of extensive investigations, and these properties make MCM-41 material among the best candidates as the hosts for many guest materials [7–10], especially semiconductor nanoparticles, which may prove useful in optoelectronic device applications. In this work we reported the synthesis and characterization of AlMCM-41 loaded with NiS and CoS nanoparticles. MCM-41 is a mesoporous molecular sieve and their nanoparticle-loaded forms can be prepared by addition of the nanoparticles into the sol–gel mixture arranged for the synthesis of mesoporous material [11,12]. However, incorporation of aluminum into the structure of MCM-41 materials via isomorphous substitution of aluminum for silicon, generated ion exchange sites in this mesoporous molecular sieves [13]. Therefore, cationic metals such as nickel and cobalt can be reacting with AlMCM-41 by ion exchange method. AlMCM-41 zeolite, which has been used in the present work has Si/Al ratio equal to 5.6 with diameter size 24.4 A. Here the growth of NiS and CoS nanoparticles in AlMCM-41 zeolite host obtained by Co and /or Ni ion exchange followed by treatments in Na 2 S solution in studied. The results obtained from X-ray, UV–Vis, SEM experiments are reported. Available online at www.sciencedirect.com Materials Letters 62 (2008) 655 – 658 www.elsevier.com/locate/matlet ⁎ Corresponding author. E-mail address: AFSHINPOURAHMAD@yahoo.com (A. Pourahmad). 0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2007.06.027