Synthesis of nanostructured materials using supercritical CO2: Part II. Chemical transformations

This article, the second part of our review series on the use of supercritical carbon dioxide (scCO2) for synthesis of nanostructured material deals with the production techniques that involve chemical transformations. Taking advantage of both solvent and anti-solvent tunable properties of scCO2, many nanostructured materials including supported/unsupported nanoparticles, quantum nanodots, nanofilms, nanorods, nanofoams, and nanowires can be prepared. Furthermore, material surfaces can be functionalized using scCO2. scCO2 can also be used as a carbon source for the controlled synthesis of carbon nanotubes and fullerenes or as an oxygen source for metal oxide nanostructures. Moreover, materials produced using scCO2 does not usually need additional purification or drying steps. Depending on surface properties, the morphology of the final material can be adjusted by tuning the process conditions and the reactant concentrations.