Graphite and Bismuth Selenide under Electrical Explosion in Confined Environment: Exfoliation, Phase Transition, and Surface Decoration

Electrical explosion, characterized by ultrafast atomization and quenching rate (dT/dt approximate to 10(10)-10(12) K s(-1)) of the sample, is a unique approach for "one-step" synthesis of nanomaterials. Experiments are carried out with layered graphite and Bi2Se3 under the action of electrical explosion in a confined reaction tube. High-speed photography and electrophysical diagnostics are applied to characterize dynamic processes. SEM and EDS are used to characterize surface micro-morphology of reaction products. The layered materials are first exfoliated to thin nanosheets/nanocrystals by shock waves and turbulent flow of the explosion. As the ionized explosion products (>10 000 K) contacts the sample, intense heat transfer happens, simultaneously atomizing the sample and quenching the plasmas. As a result, nanoparticles grow on the surface of thin sheets, forming "dot-sheet" structure. The size distribution of the nanoparticles typically ranges from 10 to 100 nm, following Log-normal distribution. The dotted graphite nanosheets gather together and form a stacked/cabbage-like structure. By contrast, Bi2Se3 case accompanies with chemical reactions, causing surface corrosion and showing more possibilities: nanocrystals and nanotubes growth on different areas of the sample.