Electrocrystallization of Mutually Crossed Bismuth Telluride Nanoplatelets

Bismuth telluride (Bi2Te3) is the most well-known compound for thermoelectric cooling and generation applications at low temperature regime. Recently, nanostructured thermoelectrics is found to be an effective route of improving thermoelectric properties due to its notably reduced thermal conductivity. Here, we investigate the growth mechanism of mutually crossed Bi2Te3 nanoplatelets formed in the initial stage of electrodeposition of Bi2Te3 films on Ti substrates. The individual nanoplatelet is identified to be a single crystal disk with [001] as a surface normal. The preferential growth of {0001}-oriented crystal is attributed to anisotropic bonding nature and electrical conductivity of Bi2Te3. The specific interplanar angles measured from different mutually crossed nanoplatelets suggest {10 (1) over bar 10} and {10 (1) over bar5} to be the twin planes of two {0001}-oriented Bi2Te3 crystals. A model based on crystal twinning during electrocrystallization of Bi2Te3 is presented to explain the observed crystal morphology of mutually crossed nanoplatelets. The understanding of Bi2Te3 crystal growth mechanism shall lead to the effective strategy to develop nanostructured thermoelectrics by electrocrystallization. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3493591] All rights reserved.