Synthesis of Hematite (r-Fe2O3) Nanorods Diameter-Size and Shape Effects on Their Applications in Magnetism, Lithium Ion Battery, and Gas Sensors 直径大小和形状对其在磁性、锂离子电池和气体传感器中应用的影响.pdf

17806 J. Phys. Chem. B 2006, 110, 1780617812 Synthesis of Hematite (-Fe O ) Nanorods: Diameter-Size and Shape Effects on Their 2 3 Applications in Magnetism, Lithium Ion Battery, and Gas Sensors Changzheng Wu, Ping Yin, Xi Zhu, Chuanzi OuYang, and Yi Xie* Department of Nano-materials and Nano-chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Uni ersity of Science Technology of China, Hefei, Anhui 230026, China Recei ed: June 1, 2006; In Final Form: July 16, 2006 We demonstrated in this paper the shape-controlled synthesis of hematite (-Fe O ) nanostructures with a 2 3 gradient in the diameters (from less than 20 nm to larger than 300 nm) and surface areas (from 5.9 to 52.3 2 m /g) through an improved synthetic strategy by adopting a high concentration of inorganic salts and high temperature in the synthesis systems to influence the final products of hematite nanostructures. The benefits of the present work also stem from the first report on the 20-nm-diameter and porous hematite nanorods, as well as a new facile strategy to the less-than-20-nm nanorods, because the less-than-20-nm diameter size meets the vital size domain for magnetization properties in hematite. Note that the porous and nonporous hematite one-dimensional nanostructures with diameter gradients give us the first opportunity to investigate the Morin temperature evolution of nanorod diameter and porosity. Evidently, the magnetic properties