Highly Porous Thermoelectric Nanocomposites with Low Thermal Conductivity and High Figure of Merit from Large-Scale Solution-Synthesized Bi2Te2.5Se0.5 Hollow Nanostructures

To enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (kappa) and excellent figure of merit (z T). Herein we report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi2Te2.5Se0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm x h 10 mm) with low kappa (0.48 W m(-1) K-1) and the highest zT (1.18) among state-of-the-art Bi2Te3-xSex materilas. Additional benefits of the unprecedented low relative density (68-77%) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase-transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields.