Nanoscale thermoelectric properties of Bi2Te3 – Graphene nanocomposites: Conducting atomic force, scanning thermal and kelvin probe microscopy studies

Thermoelectric Properties of Reduced Graphene Oxide/Bi2Te3 Nanocomposites

“…Carbon nanotubes and graphene have shown high electrical conductivity, high carrier mobility, and high mechanical properties [10,11], and have been widely used in the research on inorganic TE composite materials [12][13][14][15][16][17][18][19]. For example, Dong et al [12] prepared PbTe/graphene nanocomposite powders by a wet chemical method, and then sintered the as-prepared powders by a spark plasma sintering (SPS) process at 580 • C, and a ZT value of 0.7 was obtained at 670 K for the composite with 5% mass ratio of graphene: PbTe.…”

“…For example, Dong et al [12] prepared PbTe/graphene nanocomposite powders by a wet chemical method, and then sintered the as-prepared powders by a spark plasma sintering (SPS) process at 580 • C, and a ZT value of 0.7 was obtained at 670 K for the composite with 5% mass ratio of graphene: PbTe. Ju et al [13] fabricated Bi 2 Te 3 nanowire (NW)/graphene composite films by wet chemical synthesis combined with a sintering process, and a ZT value of 0.2 was obtained for the composite film with 20 wt% Bi 2 Te 3 NWs at 300 K. Liang et al [14] prepared Bi 2 Te 3 /graphene bulk materials by a hydrothermal process combining SPS method, and a ZT value of 0.21 was obtained for the composite with 0.2 vol.% graphene at 475 K. Agarwal et al [15] prepared Bi 2 Te 3 /graphene bulk materials by a cold pressing method, and a ZT value of 0.92 was obtained for the composite with 0.05 wt% graphene at 402 K. Kumar et al [16] synthesized Bi 2 Te 3 /reduced graphene oxide (rGO) nanocomposites by a refluxing method, and then pressed the as-prepared nanocomposites into pellets; a ZT value of~0.35 was obtained for the pellet at~340 K. Zhang et al [17] reported Bi 0.4 Sb 1.6 Te 3 bulk materials by a high-pressure and high-temperature synthesis and high pressure sintering method, and a ZT value of 1.26 at 423 K was obtained for the composite with 0.05 wt% graphene. Ju et al [18] fabricated Bi 2 Te 3 NW/graphene bulk materials by a wet-chemical synthetic route and subsequent sintering process, and a ZT value of 0.4 was obtained for the composite with 1 wt% graphene at 300 K. Shin et al [19] prepared rGO/Bi 0.36 Sb 1.64 Te 3 composites by a melt spinning process combining SPS method, and a ZT value of 1.16 was achieved for the composite with 0.4 vol.% rGO at 393 K.…”

Enhancement of Thermoelectric Properties of Layered Chalcogenide Materials

“…by the addition of graphene increases [187]. Other studies [184,187,190,191] have shown that Seebeck coefficient followed a reverse trend.…”

“…Due to the high electrical mobility of carriers in graphene, it can maintain the electrical conductivity of the composite [3,183]. Based on a detailed literature review, graphene has not been used with layered chalcogenide materials, except in several studies with bismuth telluride and bismuth selenide [12,13,146,175,[183][184][185][186][187][188][189][190][191][192][193][194]. However, a common trend observed for all thermoelectric properties is that there is a limited content of graphene for enhancing the properties.…”

Interfacial Thermal Contact Conductance inside the Graphene–Bi2Te3 Heterostructure

“…In addition, the relatively low energy barrier at the graphene/Bi 2 Te 3 interface enables the electron to easily penetrate the interface. Thus, the reduction in the electric power factor is less pronounced, resulting in a higher overall thermoelectric power factor …”