Nanoparticle Technologies: Chapter 2. Wet Production Methods (Interface Science and Technology)

Wet and dry production methods are distinguished depending on whether the synthesis process involves a solvent or not. The majority of dry methods use top-down processes while the majority of wet methods are bottom-up. Numerous scalable wet-based approaches with minimal capital cost are described. Ability to control growth rate, surface composition, and shape are important advantages for wet-based synthesis. However, low yield and large solvent requirement are the main disadvantages. Temperature and pressure are key experimental parameters, allowing control of the final product attributes. Sonochemistry, supercritical fluid, solvothermal, microwave, electrically induced synthesis, spray pyrolysis, emulsion, sol–gel, template synthesis have been used to produce NPs. Other potential low cost and scalable techniques are also described. The majority of these techniques are still at the bench or pilot scale stages. Scalability issues could be addressed using a continuous flow reactor. The development of green processes (bio-based precursors, reduced organic solvent, and toxic chemicals) is important for the sustainability of NP technology. Quality control is a major weakness of current NP productions processes. Several purification and nanometrology methods have also been described.