Nanoporous structures: smaller is stronger.

Nanoporous structures have become the focus of intensive research in recent years owing to their unique applications in mesoscopic physics and chemistry, and potential technological applications, including sensing, catalysis, DNA translocation, and as templates for nanostructure self-assembly. The study of nanoporous structures such as nanopore-, nanocavity-, and nanochannel-array materials can afford a deep understanding of the new scientific results in such good systems with negative curvature surface. As the number of atoms near the inner surface of nanoporous structures is very large relative to the total number of atoms, the surface effects on the physical and chemical properties can be dominant. It is well known that many physical properties of nanomaterials and nanostructures such as melting temperature, surface free energy, elastic modulus, and cohesive energy show strong size effects. Nanoporous materials with large internal surface area have been more extensively employed than other nanomaterials as good host materials in nanotechnology. For example, nanoporous structures and nanocavities show a novel sink effect to capture molecules, and the effect can be controlled by tuning the pore size and porosity. Since the lower coordination of atoms of nanoporous structures can lead to the redistribution of electronic charge and change the cohesive energy of single atoms in a matrix, the mechanical responses differ from those of atoms in the bulk counterpart. Additionally, the mechanical applications of nanoporous structures are currently an important subject of much research. Thus, numerous expressions about the porosity dependence of the isotropic elastic modulus have been developed by effective medium theory. The effective elastic modulus is suitable for describing the mechanical