We present a facile method to prepare anisotropic nanostructure of titanium dioxide (TiO
2) and tin dioxide (SnO
2) through anisotropic self-assembly of the corresponding nanoparticles. Monodisperse TiO
2 and SnO
2 nanoparticles with size less than 10 nm assemble into a chain-like nanostructure in aqueous system with Pluronic block copolymer F127 at proper pH condition controlled by a dialysis or acid addition method. The effects of dispersion pH, F127 concentration, and heating time on the anisotropic assembly in aqueous system have been investigated systematically. The obtained nanostructure through anisotropic assembly of nanoparticles is characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results show that highly anisotropic nanostructure is achieved. Importantly, well-defined crystallographic orientations between neighboring nanoparticles are observed in TiO
2 nanochains. Such chain-like nanostructures may reduce the grain boundaries and hence enhance electron transport, which would improve the energy storage and conversion efficiency of the solar cells that are based on TiO
2 or SnO
2.
Acknowledgement
A part of this work was supported by the New Energy and Industrial Technology Development Organization (NEDO).
