Synthesis of Metal Nanostructures Using Supercritical Carbon Dioxide: A Green and Upscalable Process.

Metallic nanostructures have numerous applications as industrial catalysts and sensing platforms. Supercritical carbon dioxide (scCO2 ) is a green medium for the scalable preparation of nanomaterials. Supercritical fluid reactive deposition (SFRD) and other allied techniques can be employed for the mass production of metal nanostructures for various applications. The present article reviews the recent reports on the scCO2 -assisted preparation of zero-valent metal nanomaterials and their applications. A brief description of the science of pure supercritical fluids, especially CO2 , and the basics of binary mixtures composed of scCO2 and a low volatile substance, e.g., an organometallic precursor are presented. The benefits of using scCO2 for preparing metal nanomaterials, especially as a green solvent, are also being highlighted. The experimental conditions that are useful for the tuning of particle properties are reviewed thoroughly. The range of modifications to the classical SFRD methods and the variety of metallic nanomaterials that can be synthesized are reviewed and presented. Finally, the broad ranges of applications that are reported for the metallic nanomaterials that are synthesized using scCO2 are reviewed. A brief summary along with perspectives about future research directions is also presented.