Preparation and structure dependent thermoelectric properties of nanostructured bulk bismuth telluride with graphene

Nanostructured graphene/Bi2Te3 composites were fabricated with either Bi2Te3 powder or nanowires (NWs) and various graphene contents, and their thermoelectric properties were investigated. The Bi2Te3 powder was produced from Bi2Te3 beads with a conventional ball milling process, whereas the Bi2Te3 NWs were fabricated with a solution-phase synthetic route. The composites with a graphene content of 0.5 wt.% exhibited enhanced power factors, presumably because of an improvement in the Seebeck coefficients of the samples, which overwhelmed the reduction in electrical conductivity. In addition, the introduction of graphene reduced the lattice thermal conductivity of the composites because it caused the formation of many boundaries in the Bi2Te3 matrix. The maximum thermoelectric figure of merit (ZT) of 0.4 was achieved at 300 K with the 1 wt.%-graphene/Bi2Te3-NW composite; it was larger than that of the pristine Bi2Te3 NWs and graphene/Bi2Te3-powder composites. (C) 2016 Elsevier B.V. All rights reserved.