Improved Thermoelectric Performance of Silver Nanoparticles‐Dispersed Bi₂Te₃ Composites Deriving from Hierarchical Two‐Phased Heterostructure

Abstract

A practical and feasible bottom‐up chemistry approach is demonstrated to dramatically enhance thermoelectric properties of the Bi2Te3 matrix by means of exotically introducing silver nanoparticles (AgNPs) for constructing thermoelectric composites with the hierarchical two‐phased heterostructure. By regulating the content of AgNPs and fine‐tuning the architecture of nanostructured thermoelectric materials, more heat‐carrying phonons covering the broad phonon mean free path distribution range can be scattered. The results show that the uniformly dispersed AgNPs not only effectively suppress the growth of Bi2Te3 grains, but also introduce nanoscale precipitates and form new interfaces with the Bi2Te3 matrix, resulting in a hierarchical two‐phased heterostructure, which causes intense scattering of phonons with multiscale mean free paths, and therefore significantly reduce the lattice thermal conductivity. Meanwhile, the improved power factor is maintained due to low‐energy electron filtering and excellent electrical transport property of Ag itself. Consequently, the maximum ZT is amazingly found to be enhanced by 304% arising from the hierarchical heterostructure when the AgNPs content reaches 2.0 vol%. This study offers an easily scalable and low‐cost route to construct a wide range of multiscale hierarchically heterostructured bulk composites with significant enhancement of thermoelectric performance.

High Performance Thermoelectric Materials: Progress and Their Applications

“…Compared to TE nanomaterials, nanocomposite TE materials [95,158,[187][188][189][190] or materials containing nanoinclusions [191] are relatively easy to fabricate and investigate. Through different procedures, [67,118,192,193] bulk TE materials with nanosized substructures have been fabricated.…”

Enhanced Thermoelectric Performance of Bi2Te2.7Se0.3/Bi2S3 Synthesized by Anion Exchange Method

“…However, it is found that interfaces could hinder electron transport, such that the ZT value of the material cannot be further enhanced. The barrier‐filtering effect may occur at the reasonable heterointerfaces, which could filter the low‐energy carriers to enhance Seebeck coefficient S but not obviously influence electrical conductivity σ of materials . Therefore, optimizing the electron and phonon transport of the material is key to improve thermoelectric properties by designing reasonable heterointerfaces.…”

Synergistic Optimization of Thermoelectric Performance in P-Type Bi0.48Sb1.52Te3/Graphene Composite

“…Nanocomposite has been suggested to be an effective approach to synergistically tune the electrical and the thermal properties by introducing second phase nanoparticles into the matrix [12][13][14][15][16][17][18]. Lots of materials, such as ZnAlO, WSe 2 and silver, have been used as second phase nanoparticles to enhance the TE performance of Bi 2 Te 3 -based alloys [16][17][18][19]. Not all composites show synergistic optimization…”

“…Due to the additional graphene, the composites show an improved power factor of 4.8ˆ10´3 Wm´1K´2 with modified carrier concentration and suppressed lattice thermal conductivity. Consequently, synergistic optimization in electrical and lattice properties by additional graphene leads to a great improvement in the figure of merit ZT (1.25 at 320 K).Energies 2016, 9, 236 2 of 9 in TE performance, and some composites show decrease in the electrical properties [12,15,18,19]. Therefore, it is essential to select a proper second phase for Bi 2 Te 3 -based alloys.Graphene has very high electrical conductivity, and has been explored to be an incorporated second phase in conventional thermoelectric materials, such as PbTe, CoSb 3 , etc., to increase electrical conductivity [20][21][22][23].…”

“…Energies 2016, 9, 236 2 of 9 in TE performance, and some composites show decrease in the electrical properties [12,15,18,19]. Therefore, it is essential to select a proper second phase for Bi 2 Te 3 -based alloys.…”