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ORIGINAL PAPER

Solvothermal synthesis of hierarchically porous CeO2 nanopalm leaves and their photocatalytic properties N. Sabari Arul • D. Mangalaraj • Tae Whan Kim

Received: 10 October 2012 / Accepted: 2 January 2013 / Published online: 15 January 2013 Ó Springer Science+Business Media New York 2013

Abstract Hierarchically porous CeCO3OH palm leaves were synthesized by using a facile solvothermal method at 180 °C utilizing cerium nitrate and ethylene glycol. Polycrystalline CeO2 palm leaves were obtained from the thermal decomposition-oxidation process of the CeCO3OH nanostructures. CeCO3OH and CeO2 palm leaves were characterized by X-ray diffraction pattern, scanning electron microscopy image, energy dispersive X-ray analyses, and ultraviolet (UV)–visible spectroscopy images. The CeO2 palm leaves exhibited a significant photocatalytic performance in degrading azo dye acid orange II in an aqueous solution under an UV radiation. The formation mechanisms of the CeCO3OH/CeO2 nanostructures were described on the basis of the experimental results. Keywords Nanostructured materials  Porous  Thin films  Chemical synthesis  Microstructure  AO7 dye

1 Introduction Recently, the formation of self-assembled one-dimensional (1D) and two-dimensional (2D) nanostructures into hierarchical 2D and three-dimensional (3D) complex architectures have been particularly attractive because of their excellent physical properties and potential applications in N. S. Arul  T. W. Kim (&) Department of Electronic Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea e-mail: [email protected] N. S. Arul  D. Mangalaraj Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046, India

optoelectronic devices [1]. Substantial research development efforts have been performed to prepare various complex nanostrucutures through template and structure directing agents [2]. It is still a great task to prepare 2D and 3D architectures without templates and structure directing agents. Studies concerning synthesis of precisely shape controlled and spatially patterned novel micro/nanostructures with various superstructures have been performed by many researchers [3–6]. Among the several types of morphologies, the hierarchical morphology have attracted considerable attention due to their novel physical properties, better efficiency, and the enhancement in the interfacial charge carrier transfer rate [7, 8]. Cerium oxide (CeO2) semiconductors are of current interest because of their potential applications in oxygen sensors, solar cells, catalysts, and solid oxide fuel cells [9– 11], because they have distinctive physical properties including large energy band gap of 3.2 eV. Nanostructural CeO2 has been paid a lot of attention due to its unique physical and chemical properties. The surface area and particle size of the CeO2 have an exceptional impact over sensitivity, conductivity, and catalytic activity properties. Various methods have been used to deposit CeO2 thin films [12–15]. Inv