High-Yield Production of Nanoplatelet Bi2Te3 via Supercritical Ball Milling in Carbon Dioxide

Nanoplatelet Bi₂Te₃ is highly desired as a starting to powder for the consolidation of bulk nanostructured thermoelectric legs, as low-dimensional Bi₂Te₃ has long been expected to result in a higher Seebeck coefficient and lower thermal conductivity, leading to an unprecedented enhancement in the thermoelectric figure of merit (zT) in this material. The production of few-layer Bi₂Te₃ nanoplatelets has thus far mainly been limited to low-yield hydrothermal synthesis techniques. Studies have suggested that Bi₂Te₃ degrades in the presence of water, making such hydrothermal techniques inherently non-ideal for the production of high thermoelectric performance Bi₂Te₃ nanoplatelets. In this study, we show that gram-yield quantities of few-layer Bi₂Te₃ nanoplatelets are preferentially exfoliated along the basal plane using a novel, “all-dry” supercritical carbon dioxide (scCO₂) ball milling technique. We will discuss advantages of our method in terms of the size, morphology, and crystallinity of the resulting nanoplatelets are compared against conventional ball milling techniques.