Nanoengineered thermoelectric (TE) materials have received a great attention because of the potential improvements in the thermoelectric figure of merit (ZT), due to the classical and quantum mechanical size effects on electrons and phonons that provide additional mechanisms to enhance TE properties. The achievement of thermoelectric ZT of ~2-3 in painstakingly grown two-dimensional (2-D) nanostructures has been experimentally proved while a ZT exceeding 5 was theoretically predicted in 1-D nanostructures. In the design of TE materials, nanotubes offer an additional degree of freedom compared to other 1-D nanostructures because the wall-thickness can be controlled in addition to length and diameter. Changes in wall-thickness are expected to strongly alter the electrical and phonon transport properties and thereby enhance the overall TE properties.
In this work, we demonstrated high scalability and cost-effective nanofabrication to synthesize ultra-long hollow AgPbSbTe (LAST) nanofibers by combining electrospinning (ES) and a galvanic displacement reaction (GDR). Control over the diameter, wall-thickness, morphology, composition and crystallinity of the nanofibers was achieved by tuning the shape and dimension of the sacrificial material as well as GDR conditions. Electrical and thermoelectric properties of the nanofibers were correlated to dimension, crystallinity and composition.