Toward refinement and homogenization of heterogeneous metal nanoparticle prepared by electrical explosion with spatial filter

The ability to synthesize nanoparticles (NPs) with desirable structural/compositional properties has been the driving goal of functional material applications. As a “one-step” evaporation-condensation method for NPs production, the electrical explosion can achieve ultrafast heating/quenching rates (dT/dt ∼ 10¹⁰ K/s) of current-carrying metals. This study proposes a spatial filter to control explosion energy release and product quenching procedure. A supersonic plasma jet (>2 Mach) erupts through the small hole of the filter, forming a high-pressure homogenizer structure, enhancing the diffusion and cooling down of explosion products. Microscopic characterization indicates NPs size decreases from 46.3^±16.7 to 27.7^±7.7 nm. Structural study has yielded two assembly routes of NPs: the first involves the top-down approach (Cu particles >100 nm), while the second concerns the bottom-up way (Cu and Cu_xO NPs <100 nm). The improved performance is attributed to the multi-stage control of explosion products, resulting in less instability development and a more reasonable evaporation-condensation process.