ZnO/Zn-Al layered double hydroxide (ZnO/Zn-Al LDH) hierarchical architecture, a new type of ZnO-based heterostructure, has been synthesized directly on an Al substrate via a facile solution phase process. The firecracker-like heterostructures consist of uniform ZnO nanorods orderly standing at the edges of two-dimensional (2D) surfaces of Zn-Al LDH nanoplatelets. Experimental result obtained from the early growth stage indicates that the underlying Zn-Al LDH nanoplatelet arrays are well constructed with their (00l) planes perpendicular to the surface of Al substrate. We propose that the "edge ...