Effect of copper doping on the crystal structure and morphology of 1D nanostructured manganese oxides.
We have tried to control the aspect ratio and physicochemical properties of 1D nanostructured manganese oxides through copper doping. Copper-doped manganese oxide nanostructures have been synthesized by one-pot hydrothermal treatment for the mixed solution of permanganate anions and copper cations. According to powder X-ray diffraction and electron microscopic analyses, all the present materials commonly crystallize with alpha-MnO2-type structure but their aspect ratio decreases significantly with increasing the content of copper. Such a variation of crystallite dimension is attributable to the limitation of crystal growth by the incorporation of copper ions. X-ray absorption spectroscopic studies at Mn K- and Cu K-edges clearly demonstrate that the average oxidation state of manganese ions is increased by the substitution of divalent copper ions. Electrochemical measurements reveal the improvement of the electrode performance of nanostructured manganate upon copper doping, which can be interpreted as a result of the decrease of aspect ratio and the increase of Mn valence state. From the present experimental findings, it becomes certain that the present Cu doping method can provide an effective way of controlling the crystal dimension and electrochemical property of 1D nanostructured manganese oxide.
Division of Nano Sciences, Department of Chemistry, Center for Intelligent Nano-Bio Materials (CINBM), Ewha Womans University, Seoul 120-750, Korea.
Sun Hee
SH
Lee
Dae Hoon
DH
Park
Seong-Ju
SJ
Hwang
Jin-Ho
JH
Choy
D003300:Copper / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
D046911:Macromolecular Substances; D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D003300:Copper