Rattle-type Carbon-Alumina Core-Shell Spheres: Synthesis and Application for Adsorption of Organic Dyes Jiabin Zhou, † Chuan Tang, † Bei Cheng, † Jiaguo Yu,* ,† and Mietek Jaroniec* ,‡ † State Key Laboratory of Advanced Technology for Materials Synthesis and Processing and School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, P. R. China ‡ Department of Chemistry & Biochemistry, Kent State University, Kent, Ohio 44242, United States * S Supporting Information ABSTRACT: Porous micro- and nanostructured materials with desired morphologies and tunable pore sizes are of great interests because of their potential applications in environmental remediation. In this study, novel rattle- type carbon-alumina core-shell spheres were prepared by using glucose and metal salt as precursors via a simple one-pot hydrothermal synthesis followed by calcination. The microstructure, morphology, and chemical composition of the resulting materials were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 adsorption-desorption techniques. These rattle-type spheres are composed of a porous Al 2 O 3 shell (thickness ≈ 80 nm) and a solid carbon core (diameter ≈ 200 nm) with variable space between the core and shell. Furthermore, adsorption experiments indicate that the resulting carbon-alumina particles are powerful adsorbents for the removal of Orange-II dye from water with maximum adsorption capacity of ∼210 mg/g. It is envisioned that these rattle-type composite particles with high surface area and large cavities are of particular interest for adsorption of pollutants, separation, and water purification. KEYWORDS: rattle-type spheres, carbon-alumina, hollow spheres, adsorption, organic dyes 1. INTRODUCTION In recent years, the fabrication of inorganic micro- and nanosized hollow and rattle-type core/shell materials has attracted a lot of attention because of the materials' versatile applications including catalysts, chemical sensors, medicine, drug/gene reservoirs, and adsorbents. 1-5 These core-shell composites often exhibit relatively high surface area, increased stability and superior magnetic and optical properties. 6,7 The major strategies to prepare such structures are based on the use of various templates including hard and soft templates, as well as template-free routes. 8-15 Recently, the colloidal carbona- ceous spheres have been employed as a green and novel template to synthesize hollow structures of a variety of materials. 16-18 The resulting products inherit the spherical morphology of the carbon particles and possess favorable porous properties. Nowadays the rattle-type nanoarchitectures, a special class of core/shell particles, have been extensively studied because of their unique structural properties and potential applications. These architectures possess spherical shells and solid cores having a variable space between them. 19 Some rattle-type particles such as Au-polymer, SiO 2 -Fe 2 O 3 nanoball, and Cu- silica have been synthesized; 20-22 however, the existing synthesis strategies are often complicated because of tedious procedures and poor reproducibility. Thus, there is still a challenge to develop simple, controllable, and environmentally friendly methods for the synthesis of the rattle-type particles. Herein, we present a facile and effective strategy to fabricate rattle-type carbon-alumina core-shell spheres with large cavities using colloidal carbon spheres as hard templates. The as-prepared products exhibit spherical morphology, relatively high surface area, and porous structures. Experimental study of their performance as adsorbents for dye pollutants from water showed that they are very promising materials for wastewater treatment. 2. EXPERIMENTAL SECTION Sample Preparation. All the chemicals were analytical grade from Shanghai Chemical Industrial Company and were used without further purification. In a typical synthesis, 20.1 mmol of glucose and the desired amount of aluminum nitrate (2.01, 4.02, 10.05 mmol) were respectively dissolved in 60 mL of distilled water under vigorous stirring. When the mixture solution was fully dissolved, 10 mL of ethanol were added under stirring. The resultant mixture was placed in a 100 mL Teflon-lined stainless steel autoclave and heated at 180 °C for 24 h. The black products were then collected, washed three times with water and ethanol, and dried at 80 °C for 5 h. To obtain the rattle-type carbon-alumina spheres, we heated the dried products at Received: January 31, 2012 Accepted: March 29, 2012 Published: March 29, 2012 Research Article www.acsami.org © 2012 American Chemical Society 2174 dx.doi.org/10.1021/am300176k | ACS Appl. Mater. Interfaces 2012, 4, 2174-2179