Green synthesis of flower-like CuI microstructures composed of trigonal nanostructures using pomegranate juice Farnosh Tavakoli a , Masoud Salavati-Niasari a,b,n , Fatemeh Mohandes b a Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran b Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran article info Article history: Received 26 January 2013 Accepted 27 February 2013 Available online 7 March 2013 Keywords: Microstructure Crystal growth Nanocrystalline materials abstract In this work, pomegranate juice was used not only as reductant, but also as capping agent for self- assembly of trigonal nanostructures to form flower-like CuI microstructures. Pomegranate juice was applied as reductant because of the presence of anthocyanin molecules in its ingredients. Besides pomegranate juice, Cu(NO 3 ) 2 .3H 2 O and LiI were used as copper and iodide sources for the preparation of CuI nanostructures via a simple precipitation method at ambient conditions. By using different amounts of pomegranate juice, various morphologies of CuI have been obtained. It was found that uniform flower-like CuI microstructures composed of trigonal nanostructures have been successfully produced using 8 mL of pomegranate juice. & 2013 Elsevier B.V. All rights reserved. 1. Introduction CuI nanocrystalline materials have attracted much attention because of their unusual properties such as large band gap, negative spin-orbit splitting and diamagnetism behavior [1,2]. CuI has three crystalline phases: g-CuI (below 350 1C), b-CuI (between 350 and 392 1C) and a-CuI (above 392 1C) [1]. CuI is very useful in dye sensitized solid state solar cell as a hole transporting and collecting agent. It can also be used as a catalyst in organic synthesis, solid state X-ray and g-ray detectors and solid electrolytes in solid state batteries [3,4]. So far, several physical and chemical methods have been developed to synthe- size CuI nanostructures [5–7]. Recently, great efforts were made to use green and environ- mentally friendly methods for the synthesis of nano-sized mate- rials. These efforts involve the use of plant or fruit extracts as stabilizer and capping agent to control crystal growth [8,9]. These green methods are low cost, fast, efficient, and generally lead to the formation of crystalline nanostructures with a variety of shapes. In this work, we present a green, one step, and cost- efficient method for the synthesis of CuI nanostructures using pomegranate juice. In addition, the amount of pomegranate juice was changed to form different morphologies of CuI nanostruc- tures. The as-produced nanostructures were characterized with the aid of SEM, TEM, XRD, UV–vis, PL and EDS. 2. Materials and methods Cu(NO 3 ) 2 .3H 2 O and LiI were purchased from Merck Company (pro-analysis) and used without further purification. CuI nanos- tructures were prepared by the following experimental sequence: first, a certain amount of pomegranate juice was added dropwise into the copper nitrate solution (2 mmol of Cu(NO 3 ) 2 .3H 2 O dis- solved in 50 mL of distilled water) under magnetic stirring, and then the lithium iodide solution (2 mmol of LiI dissolved in 50 mL of distilled water) was added dropwise into the above solution. The obtained mixture was stirred at room temperature for 30 min. The resultant white precipitates were filtered, washed by distilled water and absolute ethanol and dried at 50 1C in vacuum. The experiment was carried out by using 0.5, 1.5, 2.5, 5, 8, 10, 16, and 20 mL of pomegranate juice at the same conditions, respectively. 3. Results and discussion The effect of the amount of pomegranate juice on the mor- phology of the products was investigated. When 0.5 mL of pomegranate juice was used, particle-like shapes with irregular particle sizes in the range of 45–50 nm were formed (Fig. 1a). Fig. 1b shows SEM image of the product synthesized by 1.5 mL of pomegranate juice. In this stage, uniform nanoparticles with grain size of about 35 nm were obtained. Although morphology of the products prepared by 2.5 (Fig. 1c) and 5 mL (Fig. 1d) of pome- granate juice were the same, the presence of some trigonal shapes was observed in the SEM image of the product synthesized using 5 mL of pomegranate juice (Fig. 1d). Particle sizes of the CuI Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/matlet Materials Letters 0167-577X/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2013.02.114 n Corresponding author at: University of Kashan, Institute of Nano Science and Nano Technology, Institute of Nano Science, Kashan 87317-51167, Iran. Tel.: þ98 361 591 2383; fax: þ98 361 555 2935. E-mail address: salavati@kashanu.ac.ir (M. Salavati-Niasari). Materials Letters 100 (2013) 133–136