Room temperature synthesis of a novel γ-MnO2 hollow structure for aerobic oxidation of benzyl alcohol

A novel gamma-MnO(2) hollow structure has been synthesized at room temperature using a simple chemical reaction between MnSO(4) and KMnO(4) in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. The synthesized gamma-MnO(2) hollow structure was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET analysis. It was found that the hollow structure consisting of short gamma-MnO(2) nanorods with diameters of 5-10 nm and lengths of 50-100 nm could form when the MnSO(4)/KMnO(4) mole ratio was equal to or larger than 2.3. The excess amount of Mn(2+) in solution was observed to promote the crystallization of gamma-MnO(2) nanorods and the formation of the gamma-MnO(2) hollow structure. In addition, the evolution of microstructure and morphology of the products obtained with a MnSO(4)/KMnO(4) mole ratio of 2.3 at different reaction times revealed that the hollow structure was formed via an Ostward ripening process. Furthermore, the obtained gamma-MnO(2) hollow structure was found to exhibit a better catalytic performance than conventional gamma-MnO(2) in the aerobic oxidation of benzyl alcohol to benzaldehyde, demonstrating its possible application in alcohol oxidation.

[1]  Hua Chun Zeng,et al.  Preparation of Hollow Anatase TiO2 Nanospheres via Ostwald Ripening. , 2004, The journal of physical chemistry. B.

[2]  S. Suib,et al.  Efficient, Catalytic, Aerobic Oxidation of Alcohols with Octahedral Molecular Sieves. , 2001, Angewandte Chemie.

[3]  Changzheng Wu,et al.  MoS2 hierarchical hollow cubic cages assembled by bilayers: one-step synthesis and their electrochemical hydrogen storage properties. , 2006, Chemical communications.

[4]  S. Suib,et al.  Particle Size Control of Cryptomelane Nanomaterials by Use of H2O2 in Acidic Conditions , 2005 .

[5]  Y. Qian,et al.  In-Situ Source–Template–Interface Reaction Route to Semiconductor CdS Submicrometer Hollow Spheres , 2000 .

[6]  Xun Fu,et al.  Fabrication of hollow spheres and thin films of nickel hydroxide and nickel oxide with hierarchical structures. , 2005, The journal of physical chemistry. B.

[7]  Xun Wang,et al.  Rational synthesis of α-MnO2 single-crystal nanorods , 2002 .

[8]  Jian Gong,et al.  Synthesis of Manganese Oxide Hollow Urchins with a Reactive Template of Carbon Spheres , 2008 .

[9]  C. Feng,et al.  Low-temperature synthesis of alpha-MnO2 hollow urchins and their application in rechargeable Li+ batteries. , 2006, Inorganic chemistry.

[10]  Yadong Li,et al.  Selected-Control Hydrothermal Synthesis of α- and β-MnO2 Single Crystal Nanowires , 2002 .

[11]  Younan Xia,et al.  Preparation of Mesoscale Hollow Spheres of TiO2 and SnO2 by Templating Against Crystalline Arrays of Polystyrene Beads , 2000 .

[12]  D. Portehault,et al.  Morphology Control of Cryptomelane Type MnO2 Nanowires by Soft Chemistry. Growth Mechanisms in Aqueous Medium , 2007 .

[13]  Steven L. Suib,et al.  Hydrothermal Growth of Manganese Dioxide into Three‐Dimensional Hierarchical Nanoarchitectures , 2006 .

[14]  W. Cai,et al.  A Hierarchically Structured Ni(OH)2 Monolayer Hollow‐Sphere Array and Its Tunable Optical Properties over a Large Region , 2007 .

[15]  Yadong Li,et al.  Synthesis and formation mechanism of manganese dioxide nanowires/nanorods. , 2003, Chemistry.

[16]  D. Portehault,et al.  Synthesis of a manganese oxide nanocomposite through heteroepitaxy in aqueous medium. , 2009, Chemical communications.

[17]  Xiong Zhang,et al.  Shape-Controlled Synthesis of 3D Hierarchical MnO2 Nanostructures for Electrochemical Supercapacitors , 2009 .

[18]  S. Brown,et al.  Efficient, aerobic, ruthenium-catalyzed oxidation of alcohols into aldehydes and ketones , 1997 .

[19]  John Aurie Dean,et al.  Lange's Handbook of Chemistry , 1978 .

[20]  R. L. Penn,et al.  Controlled growth of alpha-FeOOH nanorods by exploiting-oriented aggregation , 2006 .

[21]  Jun Chen,et al.  Facile Synthesis of Nanoporous γ-MnO2 Structures and Their Application in Rechargeable Li-Ion Batteries , 2008 .

[22]  J. Post,et al.  Manganese oxide minerals: crystal structures and economic and environmental significance. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[23]  Yong Yang,et al.  Controllable synthesis of α- and β-MnO2: cationic effect on hydrothermal crystallization , 2008, Nanotechnology.

[24]  D. Portehault,et al.  A core-corona hierarchical manganese oxide and its formation by an aqueous soft chemistry mechanism. , 2008, Angewandte Chemie.

[25]  S. Brown,et al.  Anaerobic Copper-Catalyzed Oxidation of Alcohols to Aldehydes and Ketones. , 1997 .

[26]  G. Luo,et al.  Preparation of ultrafine MnO2 powders by the solid state method reaction of KMnO4 with Mn(II) salts at room temperature , 2003 .

[27]  Yue Ding,et al.  One-step solution-based catalytic route to fabricate novel alpha-MnO2 hierarchical structures on a large scale. , 2005, Chemical communications.

[28]  G. Campet,et al.  Hydrothermal Synthesis and Pseudocapacitance Properties of α-MnO2 Hollow Spheres and Hollow Urchins , 2007 .

[29]  P. M. D. Wolff.  Interpretation of some γ‐MnO2 diffraction patterns , 1959 .

[30]  Changzheng Wu,et al.  Growth of well-aligned gamma-MnO2 monocrystalline nanowires through a coordination-polymer-precursor route. , 2003, Chemistry.

[31]  Caruso,et al.  Nanoengineering of inorganic and hybrid hollow spheres by colloidal templating , 1998, Science.

[32]  S. Suib,et al.  Self-assembly of microporous manganese oxide octahedral molecular sieve hexagonal flakes into mesoporous hollow nanospheres. , 2003, Journal of the American Chemical Society.

[33]  Jinlong Yang,et al.  Environmentally friendly gamma-MnO2 hexagon-based nanoarchitectures: structural understanding and their energy-saving applications. , 2009, Chemistry.

[34]  J. Hanson,et al.  In situ synthesis of mixed-valent manganese oxide nanocrystals: an in situ synchrotron X-ray diffraction study. , 2006, Journal of the American Chemical Society.

[35]  Qiang He,et al.  Controlled Preparation of MnO2 Hierarchical Hollow Nanostructures and Their Application in Water Treatment , 2008 .

[36]  Kangnian Fan,et al.  Fabrication of mesoporous core-shell structured titania microspheres with hollow interiors. , 2003, Chemical communications.

[37]  Fumin Wang,et al.  Highly efficient dye-sensitized solar cells with a titania thin-film electrode composed of a network structure of single-crystal-like TiO2 nanowires made by the "oriented attachment" mechanism. , 2004, Journal of the American Chemical Society.