Direct soft-chemical synthesis of chalcogen-doped manganese oxide 1D nanostructures: influence of chalcogen doping on electrode performance.
We have developed a direct nonhydrothermal route to nanostructured chalcogen-doped manganese oxides; K(x)MnO(2)Q(y) (Q = S, Se, and Te). According to combinative diffraction and microscopic analyses, the S- and Se-doped manganese oxides exhibit 1D nanowire-type morphology with layered delta-MnO(2)- and alpha-MnO(2)-structures, respectively, whereas the Te-doped compound consists of 3D nanospheres that are amorphous according to X-ray diffraction. X-ray absorption and X-ray photoelectron spectroscopy analyses clearly demonstrate that the doped chalcogen ions exist in the form of hexavalent chalcogenate clusters mainly on the sample surface or grain boundary. According to electrochemical and ex situ X-ray absorption spectroscopy investigations, the Se-doped manganate nanowires show higher structural stability and better electrode performance with excellent rate characteristics compared to the S-/Te-doped and undoped manganate nanostructures. This is attributed to the presence of chemically stable SeO4(2-) species, leading to enhanced stability of the manganate lattice through the prevention of structural deformation during cycling and/or to the improvement of Li(+) ion transport through the maintenance of intercrystallite voids. Based on the present experimental findings, we are able to conclude that the present one-pot soft-chemical route with chalcogen dopants can provide a simple method not only to economically synthesize 1D nanostructured manganese oxides but also to finely control their electrode performance, crystal structure and morphology, and lattice stability.
Kim
Tae Woo
TW
Center for Intelligent Nano-Bio Materials, Division of Nano Sciences, Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea. hwangsju@ewha.ac.kr
Park
Dae Hoon
DH
Lim
Seung Tae
ST
Hwang
Seong-Ju
SJ
Min
Bong-Ki
BK
Choy
Jin-Ho
JH
D018011:Chalcogens / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017895:Manganese Compounds / Q000737:chemistry*; D008422:Materials Testing; D008839:Microelectrodes; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
D018011:Chalcogens; D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide