Appl Phys A (2010) 100: 1097–1102 DOI 10.1007/s00339-010-5707-z Photocatalytic activity of ZnO nanoparticles prepared via submerged arc discharge method Ali Akbar Ashkarran · Azam Iraji zad · Seyed Mohammad Mahdavi · Mohammad Mahdi Ahadian Received: 6 July 2009 / Accepted: 12 April 2010 / Published online: 15 May 2010 © Springer-Verlag 2010 Abstract ZnO nanostructures were synthesized through arc discharge of zinc electrodes in deionized (DI) water. X-ray diffraction (XRD) analysis of the prepared nanostructures indicates formation of crystalline ZnO of hexagonal lat- tice structures. Transmission electron microscopy (TEM) images illustrate rod-like as well as semi spherical ZnO nanoparticles with 15–20 nm diameter range, which were formed during the discharge process with 5 A arc current. The average particle size was found to increase with the increasing arc current. X-ray photoelectron spectroscopy (XPS) analysis confirms formation of ZnO at the surface of the nanoparticles. Surface area of the sample prepared at 5 A arc current, measured by BET analysis, was 34 m 2 /g. Photodegradation of Rhodamine B (Rh. B) shows that the prepared samples at lower currents have a higher photocat- alytic activity due to larger surface area and smaller particle size. 1 Introduction Zinc oxide, with wide band gap of 3.37 eV and large exci- ton binding energy of 60 meV, has attracted much interest in recent years. It has many applications in photocatalysis, A.A. Ashkarran · A. Iraji zad ( ) · S.M. Mahdavi · M.M. Ahadian Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave., P.O. Box: 11155-8639, Tehran, Iran e-mail: iraji@sharif.edu Fax: +98-21-66164119 A. Iraji zad · S.M. Mahdavi Physics Department, Sharif University of Technology, Azadi Ave., P.O. Box: 11365-9161, Tehran, Iran gas sensors, solar cells, UV light-emitters and electronic de- vices [1]. Specifically, much attention has been drawn to- wards their photocatalytic properties because of its appli- cation in environmental purification and decomposition of toxic and organic compounds. A key requirement for im- proving the photocatalytic activity is to increase the spe- cific surface area and enhance the crystallinity [2]. These requirements are met by crystalline nanostructured mate- rials. Several methods including chemical vapor deposi- tion [3], sol–gel [4], magnetron sputtering [5], vacuum evap- oration [6], pulse laser ablation [7] and electrical arc dis- charge in vacuum conditions and controlled atmospheres [8, 9] have been used to prepare ZnO nanoparticles. For efficient photocatalytic activity, nanomaterials need to be crystalline, that is, should be grown at high temperatures or at very slow rates. In general, synthesis of ZnO usu- ally results in amorphous structures, but electrical arc dis- charge in water has the advantage in this regard as it pro- duces self-crystallized nanostructures due to high tempera- ture caused by joule heating. Moreover, compared with other techniques, electrical arc discharge in water is an attractive method because of simplicity of experimental set up, low impurity, lack of need for complicated equipments, less pro- duction steps leading to a high-throughput and cost-effective procedure to generate a high yield of nanoparticles. Also the simplicity of this method allows scaling up for mass produc- tion. The early works by arc discharge method in liquids were based on production of carbonaceous nanostructures such as MWCNTs [10–15], SWCNTs, SW-CNHs [13] and nano-onions [15]. In past few years, few papers have been published regarding synthesis of metal and metal oxide nanoparticles such as MoS 2 [16], CuO and Cu 2 O[17], Ag [18, 19], Au [20] and WO 3 [21] by arc discharge in liq- uids.