Unilamellar nanosheet of layered manganese cobalt nickel oxide and its heterolayered film with polycations.
The exfoliation of layered Li[Mn(1/3)Co(1/3)Ni(1/3)]O(2) into individual monolayers could be achieved through the intercalation of quaternary tetramethylammonium (TMA(+)) ions into protonated metal oxide. An effective exfoliation occurred when the TMA(+)/H(+) ratio was 0.5-50. Reactions outside this range produced no colloidal suspension, but all the manganese cobalt nickel oxides precipitated. Atomic force microscopy and transmission electron microscopy clearly demonstrated that exfoliated manganese cobalt nickel oxide nanosheets have a nanometer-level thickness, underscoring the formation of unilamellar nanosheets. The maintenance of the hexagonal atomic arrangement of the manganese cobalt nickel oxide layer upon the exfoliation was confirmed by selected area electron diffraction analysis. According to diffuse reflectance ultraviolet--visible spectroscopy, the exfoliated manganese cobalt nickel oxides displayed distinct absorption peaks at approximately 354 and approximately 480 nm corresponding to the d-d transitions of octahedral metal ions, which contrasted with the featureless spectrum of the pristine metal oxide. In the light of zeta potential data showing the negative surface charge of manganese cobalt nickel oxide nanosheets, a heterolayered film of manganese cobalt nickel oxide and conductive polymers could be prepared through the successive coating process with colloidal suspension and polycations. The UV--vis and X-ray diffraction studies verified the layer-by-layer ordered structure of the obtained heterolayered film, respectively.
Oh
Eun-Jin
EJ
Department of Chemistry and Nano Sciences, Ewha Womans University, Center for Intelligent Nano-Bio Materials, Seoul 120-750, Korea.
Kim
Tae Woo
TW
Lee
Kyung Min
KM
Song
Min-Sun
MS
Jee
Ah-Young
AY
Lim
Seung Tae
ST
Ha
Hyung-Wook
HW
Lee
Minyung
M
Choy
Jin-Ho
JH
Hwang
Seong-Ju
SJ
D003035:Cobalt / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011522:Protons; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014961:X-Ray Diffraction
D017895:Manganese Compounds; D011108:Polymers; D011522:Protons; D000644:Quaternary Ammonium Compounds; D003035:Cobalt; D009532:Nickel