Fig. 7.

a Low magnification TEM image of the bulk Bi₂Te₃ nanocomposite with 5.0 vol% AgNPs nanocomposites. b HRTEM image showing the newly-built interface between the Bi₂ Te₃ matrix and AgNPs. c Schematic drawing of a hierarchical two-phased heterostructure, showing the strong scattering of phonons with multiscale mean free paths along with the energy filtering effect. d Bottom-up assembly process to produce PbS–Ag TE nanocomposites from the assembly of PbS (blue) and Ag (red) NCs, and the corresponding band alignment of the resulting nanocomposite. e HRTEM and elemental EDX mapping of the PbS–Ag 4.4 mol% nanocomposite. f Figure of merit and schematic representation of the electron energy band alignment in PbS–Ag nanocomposite. Adapted with permission from Refs. [108, 109]. (Color figure online)