ORIGINAL PAPER Preparation of Cd(OH) 2 nanostructures in water using a simple refluxing method and their photocatalytic activity M. Barjasteh-Moghaddam • A. Habibi-Yangjeh Received: 8 January 2011 / Accepted: 20 June 2011 / Published online: 3 January 2012 Ó Iranian Chemical Society 2011 Abstract Nanostructures of Cd(OH) 2 were prepared using a simple template-free method in water by 4 h refluxing at about 95 °C without using any organic com- pound. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infrared and UV–vis diffuse reflectance spectroscopy techniques were applied for characterization of the nanostructures. The XRD pattern demonstrates that the nanostructures are crystallized in hexagonal phase. The SEM image shows that the nano- structures are nearly in plate form. The DRS of the nano- structures shows absorption maxima at about 315 nm. Photocatalytic activity of the nanostructures was investi- gated by degradation of methylene blue (MB) under UV irradiation. Moreover, the effects of refluxing time and calcination temperature on photocatalytic activity were studied. Keywords Cd(OH) 2  Photocatalysis  Nanostructures  Methylene blue Introduction Nano-sized semiconductors have drawn considerable interest in recent years, because of their properties, such as special electronic and unique optical properties as com- pared to those of the bulk materials; this is the so-called quantum confinement effect [1–3]. The surface of nanomaterials is more important than the bulk, because these materials have larger surface-to-volume ratios. Sur- face atoms are bound by weaker forces because of missing neighbors, which leads to high-surface reactivity [3]. Strategies for preparation of nanomaterials are of impor- tance in the advancement of science and technology [4]. The controlled preparation of nanomaterials has attracted much attention, as a result of their fundamental shape and size-dependent properties and important technological applications [3]. Various methods have been applied for the preparation of nano-sized semiconductors [5–8]. Among these methods, solution-based approaches are appealing due to their low temperature, low cost, high efficiency, and potential for scale-up [9–12]. In these methods, using dif- ferent templates will increase the reaction complexity, cause impurity in the products and is disadvantageous from the view point of green chemistry. Thus, development of facile, effective, and surfactant-free approaches for the controlled preparation of the nanomaterials are highly desirable. Cd(OH) 2 is a wide band gap semiconductor with a broad range of possible applications including solar cells, photo transistors and diodes, transparent electrodes, sensors, etc. [13–15]. Cadmium hydroxide is also the precursor to pre- pare cadmium oxide [15] or other functional materials (e.g., CdS, CdSe) by reaction with appropriate materials [16]. In addition, Cd(OH) 2 has applications in separation of negative charged dyes or DNA [17, 18]. Moreover, Cd(OH) 2 is a potential candidate for the application as a cathode material in batteries owing to its high stability [19]. Therefore, preparation of Cd(OH) 2 nanomaterials has been a very popular research area in recent years. Cad- mium hydroxide nanostrands with diameter of about 2 nm and length of a few micrometers were formed by raising the pH of a dilute Cd(NO 3 ) 2 solution [20]. Ghoshal et al. [21, 22] have synthesized cadmium hydroxide micro/ M. Barjasteh-Moghaddam  A. Habibi-Yangjeh (&) Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran e-mail: ahabibi@uma.ac.ir 123 J IRAN CHEM SOC (2012) 9:163–169 DOI 10.1007/s13738-011-0034-7