Electrical Explosion as a Methodology for One-Step Preparation of Nano-Materials with Particular Structure and Composition

Electrical explosion, characterized by ultrafast heating (d<i>T</i>/d<i>t</i> ~ 10¹¹ K/s) and quenching (10¹⁰ K/s) rates of the sample, is a powerful tool for synthesizing nanomaterials, including pure metal, alloy and metallic compounds and composites. This method is highly productive (200 g/h or more) and provides high-quality powders with particle size less than 100 nm; moreover, μm/mm-thick coating or film can be synthesized within a short period (μs/ms timescale). Benefitted from the simple and inexpensive device as well as the great efficient, it provides desirable possibility for industrial production. Micromorphology, microstructure and functionality should be most concerned in nanomaterials filed. Researches including our works show that the produced products characteristics is prominently influenced by the explosive behaviors and dynamic process of wires. For example, the thermal instability (e.g. stratification) in discharge process who causes the discrepant parameters of density and temperature will leads to the inhomogeneous nanoparticle size. Sufficient plasma process maintains the exploded products at a high temperature and promotes the growth process after nucleation, as a result, average particle size increases. Different breakdown modes, like surficial or internal, lead to distinctive energy deposition mechanism (Joule heating for surface breakdown and heat transport/radiation for internal) and result in relatively dispersive nanoparticles or agglomerated particle-clusters, respectively. Except nanoparticles produced by exploding wire itself, the accompanied effect, like strong shockwaves and high-speed expanded metallic products (~ km/s), is valuable in layered materials exfoliation and surface decoration. Exploding a copper wire in a graphite powder-contained tube (polymethyl methacrylate-PMMA), the strong impact of pressure and thermal metal turbulence effectively exfoliate graphite into thin nanosheets, and copper vapor quenches and nucleates on the surface of the nanosheets forming homogeneous nanoparticles (＜100 nm). A novel structure of metallic elements decorated-thin nanosheets based composite is synthesized. Moreover, other layered materials (e.g., black phosphorus and bismuth selenide) can also be exfoliated and decorated by this method. To sum up, whatever use exploding wire as the source for nanomaterials production or as a tool for materials treatment due to its high-pressure and temperature attributions, explosive behaviors and dynamic process are the most substantial influenced elements. Further investigating on the physical mechanisms can give a significative guidance on practical application.