Fabrication of architectures with dual hollow structures : Arrays of Cu 2o nanotubes organized by hollow nanospheres

Highly ordered array of hierarchical nanotubes constructed from Cu ₂O hollow nanospheres with a diameter of 165-185 nm and shell thickness of 20-40 nm has been synthesized by using an array of Cu(OH) ₂ nanorods as a sacrificial template. The formation of Cu ₂O nanotubes is considered to be the result of the "Kirkendall effect", while evolution of the Cu₂O hollow nanospheres from solid nanospheres in the walls results from, the "Ostwald ripening" process. Furthermore, the Kirkendall effect in nanoscaled synthesis has been directly proven by the successful design and synthesis of arrays of Cu ₂O/Cu_2-xSe heterogeneous nanotubes constructed from Cu₂O hollow seminanospheres covered on both the inner and the outer surfaces of Cu_2-xSe sheaths with a thickness about 5-10 nm, in which the diffusion rate of copper ions through the Cu_2-xSe sheaths is shown to be double that of ascorbic acid molecules during the reaction process. This work offers a new strategy to study the diffusion rate relationship between diffusion couple in nanoscaled synthesis and provides a novel approach for controllable synthesis of hierarchical architectures with dual hollow nanostructures © 2009 American Chemical Society.