Solution-based routes to transition-metal oxide one-dimensional nanostructures*

One-dimensional (1D) nanostructures have drawn continuous research attention because of their unique electrical, optical, and magnetic properties different from that of bulk and nanoparticles, as well as their potential applications in mesoscopic research and nanodevices. The main challenge in this area is how to precisely control the sizes, dimensionalities, compositions, and crystal structures in nanoscale, which may serve as a powerful tool for the tailoring of physical/chemical properties of materials in a controllable way. Here, we review the advances in the solution-based routes to prepare 1D nanostructures. Particularly, three systems of MnO2, rare-earth compounds, and silicates have been chosen to show the synthetic strategy under hydrothermal conditions. As the main theme, a rolling mechanism has been given special attention to present a relative general understanding of the growth of various transition-metal oxide (TMO) 1D nanostructures under solution conditions.