Synthesis of replica mesostructures by the nanocasting strategy

Since mesoporous silicates (M41S) were first discovered in the early 1990s, organic-inorganic assembly combined with sol-gel processes by using surfactants as structure-directing agents had been considered to be the major pathway for creating mesoscaled periodic materials. However, unfortunately, many mesostructured materials could not be prepared by the sol-gel process. Nanocasting, using highly ordered mesoporous silica as a template, has brought forward incredible possibilities in preparing novel mesostructured materials, and has led to a great number of ordered nanowire arrays with: a) small diameter (< 10 nm); b) large surface areas (up to 2500 m(2) g(-1)) and uniform mesopores ( 1.5-10 nm); c) tunable 2-D or 3-D mesostructures; d) controlled morphology such as spheres, rods, films, and monoliths; and e) different components including carbon, metals, metal oxides and metal sulfides. We intend to review the results of research into replica mesostructures by nanocasting in recent years from the viewpoint of synthesis. Detailed synthetic processes are described, and problems that are often encountered in the procedure are discussed with several solutions. Many mesostructured replicas are introduced, sorted by their components, including synthetic methods, characteristics of the materials, applications and future challenges. Finally, a simple view of the prospects in this area is provided.