Large-scale synthesis of nanoparticles
High-purity nanoparticles are most in demand for their antibacterial activity in textiles, their catalytic activity in membrane reactors, their flame retardant properties in composite polymers, or for improving solar cell efficiency. Nanoparticles can either be derived from bulk materials or synthesised by bottom-up approaches, namely from atomic or molecular species through chemical reactions that allow particles to grow in size. Until now, production of precursor-free nanoparticles typically involved use of conventional plasma reactors. However, the size and complexity of the set-up have been posing a barrier to their widespread use in industry. What is more, other nanoparticle production methods such as the use of arc discharge systems are instable, not being able to run for more extended periods of time, and similarly to spark discharge systems, to have a low production rate. The EU-funded project BUONAPART-E (Better upscaling and optimization of nanoparticle and nanostructure production by means of electrical discharges) advanced the arc- and spark-discharge methods for synthesising high-purity metallic nanoparticles into stable and low-cost processes, with high production rates and high energy efficiency. The advanced processes allow synthesis of different materials using the same platform whose basic evaporation unit is a set of electrodes. Minimal impact on the environment is ensured by avoiding use of hazardous chemical precursors and solvents, while recycling inert gases. A major advantage is the possibility of producing tailor-made nanoparticles, of specific sizes and properties. By using inexpensive power supplies and a set of electrodes, scientists increased gas evaporation rates by tenfold, obtaining for example 36 g/h (Zn), 4.4 g/h (Cu) and 1 g/h (Ag). The team then increased the process throughput by putting in parallel 16 electrode sets, obtaining the same product quality, production rate and energy consumption. Three patent applications for the arc-discharge method were filed. The spark-discharge process was further improved by developing a high-frequency power supply that allows obtaining frequencies up to 9 kHz instead of a few hundreds, as well as by keeping particle sizes small. Using these simple and low-cost nanoparticle generation methods, project consortium demonstrated several applications of nanoparticle integration into intermediate or final products. BUONAPART-E demonstrated viable and highly sustainable routes to scaling up nanoparticle production to industrial dimensions. The newly developed flexible platform enables synthesis of high-quality nanoparticles according to customer demands at competitive costs.
Keywords
Nanoparticles, BUONAPART-E, electrical discharges, textiles, membrane reactors, solar cells
