The synthesis of the faceted single-crystalline h-AlN nanotubes with the length of a few micrometers and diameters from 30 to 80 nm is first reported. This provides an ideal substrate for the construction of GaN-based nanoheterostructures in future nanoelectronics. The experimental results suggest the further extensive experimental and theoretical studies on the promising nonlayered nanotubular structures.

We present a two-step synthesis process to produce hierarchical ZnO nanoarchitectures that involves the preparation of ZnO nanosheet arrays by the pyrolysis of the precursor Zn5(OH)8Cl2 electrodeposited on conductive glass substrates, followed by the aqueous chemical growth (ACG) of dense ZnO single-crystalline nanowires on the surfaces of the primary ZnO nanosheets. The dye-sensitized solar cell (DSSC) based on the hierarchical ZnO nanowire−nanosheet architectures showed a power conversion efficiency of 4.8%, which is nearly twice as high as that of the DSSC constructed using a photoanode of bare ZnO nanosheet arrays. The better photovoltaic performance of hierarchical ZnO nanoarchitecture DSSC was due to a better dye loading and light harvesting as a consequence of the enlargement of the internal surface area within the photoanode. Moreover, the improved performance for the DSSC with the hierarchical ZnO nanowire−nanosheet architectures may be also ascribed to more light scattering behavior through extending the optical path length within the photoanode so as to increase the light harvesting. The results demonstrate potential application of the hierarchical ZnO nanoarchitectures derived from ZnO nanosheet arrays for highly efficient DSSCs.

Controllable synthesis of well-shaped nanocrystals is of significant importance for understanding the surfacerelated properties as well as for the exploration of potential applications. Herein, CeO 2 nanorods and nanocubes were selectively synthesized using cerium(III) chloride and cerium(III) nitrate as precursor, respectively. Counter anions of the cerium source were crucial to the shapes of the resulting products. Intriguingly, the as-synthesized nanorods could be converted into nanocubes by the addition of an appropriate amount of NO 3ions into the hydrothermal reaction. The NO 3ions are considered as both a capping agent and an oxidizer during the formation of CeO 2 nanocubes. Moreover, the influences of several others anions are investigated. Br -, I -, and SO 4 2ions have similar roles to Clions, which lead to the formation of nanorods. The introduction of BrO 3ions can bring on the generation of irregular nanoparticles because they can function as an oxidizer but not a capping agent. The anion-induced controllable growth process is simple and low cost, which makes this strategy potentially useful for the preparation of other faceted nanostructures.

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