Hierarchical titania nanotubes with self-branched crystalline nanorods.
Surface decoration strategy for one-dimensional nanostructures will improve their electrical, optical, mechanical, and electrochemical performances dramatically. Heterogeneous growth/deposition on surfaces, however, may create undesired junction interfaces in the system. Here we report a procedure during which amorphous titania nanotubes are readily self-branched with crystalline titanate nanorods at room temperature. The starting amorphous titania nanotubes were prepared by low-temperature atomic layer deposition combined with the template-directed approach. We routinely observed the self-branching phenomenon of crystalline titanate nanorods with a few nanometers in diameter onto the surfaces of the amorphous titania nanotubes in mild alkali solutions. The resulting structures were analyzed by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and electron energy loss spectroscopy. The reactivity of the hierarchical titania nanotube arrays was observed to be improved as a Li secondary battery electrode. Upon complete consumption of the amorphous body of titania nanotubes, in addition, titanate nanosheets/layers consisting of single TiO(2) layers with unit-cell thickness were obtained, elucidating the formation mechanism of layered titanate materials by alkali treatment.
National Research Lab for Nanotubular Structures of Oxides, Center for Materials and Processes of Self-Assembly, and School of Advanced Materials Engineering, Kookmin University, Seoul 136-702, South Korea.
Changdeuck
C
Bae
Youngjin
Y
Yoon
Won-Sub
WS
Yoon
Jooho
J
Moon
Jiyoung
J
Kim
Hyunjung
H
Shin
D003460:Crystallization; D011211:Electric Power Supplies; D004563:Electrochemistry / Q000379:methods; D008094:Lithium / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D043942:Nanotubes / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
D008094:Lithium; D014025:Titanium