Robust scalable synthesis of surfactant-free thermoelectric metal chalcogenide nanostructures

Abstract

, S. Xue. (2015). Robust scalable synthesis of surfactant-free thermoelectric metal chalcogenide nanostructures. Nano Energy, Robust scalable synthesis of surfactant-free thermoelectric metal chalcogenide nanostructures AbstractA robust low-cost ambient aqueous method for the scalable synthesis of surfactant-free nanostructured metal chalcogenides (MaXb, M=Cu, Ag, Sn, Pb, and Bi; X=S, Se, and Te; a=1 or 2; and b=1 or 3) is developed in this work. The effects of reaction parameters, such as precursor concentration, ratio of precursors, and amount of reducing agent, on the composition, size, and shape of the resultant nanostructures have been comprehensively investigated. This environmentally friendly approach is capable of producing metal chalcogenide nanostructures in a one-pot reaction on a large scale, which were investigated for their thermoelectric properties towards conversion of waste heat into electricity. The results demonstrate that the thermoelectric properties of these metal chalcogenide nanostructures are strongly dependent on the types of metal chalcogenides, and their figure of merits are comparable with previously reported figures for their bulk or nanostructured counterparts.

Thermoelectric Enhancement of Different Kinds of Metal Chalcogenides

“…(iii) Due to the intrinsic volatility of chalcogen elements (S, Se, Te), some metal chalcogenides possess poor thermal stability, especially for those nanoscale metal chalcogenides fabricated from bottom up processes. [131] For PLEC materials, the fast movement of liquid like metal ions could also lead to their instability. The chalcogenide nanostructures originated from spinodal decomposition are also not stable during operation because spinodal decomposition is sensitive to temperature.…”

“…[116b, 131] Another important method to enhance the thermoelectric performance of nanostructures obtained by wet chemical methods is the surface engineering of nanocrystals by using other inorganic materials to replace the capping ligands and absorbed organic solvents. [45a, 52b, 134] As the simplest agent for surface modification, hydrazine is already widely used to remove residual ligands in the wet chemical method.…”

Lead-free SnTe-based thermoelectrics: enhancement of thermoelectric performance by doping with Gd/Ag

“…1 The thermoelectric conversion efficiency is governed by the gure of merit (ZT) dened as ZT ¼ a 2 sT/(k lat + k el ), where a, s, T, k lat and k el denote the Seebeck coefficient, electrical conductivity, absolute temperature, lattice thermal conductivity and electronic thermal conductivity, respectively. 2,3 Signicant improvement in the power factor (a 2 s) coupled with low lattice thermal conductivity is necessary for enhancing the performance of present thermoelectric materials. An approach to obtaining high power factors involves manipulation of the density of states through band engineering, including band convergence/degeneracy [4][5][6] or introduction of resonant impurity levels near the Fermi level.…”

Effects of nanostructure on clean energy: big solutions gained from small features

“…Han et al [2] summarized the recent progress on different kinds of thermoelectric materials in their comprehensive review and pointed out that nanostructuring was the most important strategy for enhancing ZT values, not only because nanostructuring could effectively decrease thermal conductivity, but also because it could cause an energy filtering effect that increases the Seebeck coefficient. Later, they proposed a low-cost surfactant-free route to the synthesis of different nanostructured thermoelectric materials, and obvious enhancement of ZT was achieved [57][58][59][60]. In particular, the pronounced enhancement in ZT of some metal chalcogenide nanostructures was achieved due to the presence of nanograins or nanopores, which can effectively decrease the thermal conductivity [57].…”

“…Later, they proposed a low-cost surfactant-free route to the synthesis of different nanostructured thermoelectric materials, and obvious enhancement of ZT was achieved [57][58][59][60]. In particular, the pronounced enhancement in ZT of some metal chalcogenide nanostructures was achieved due to the presence of nanograins or nanopores, which can effectively decrease the thermal conductivity [57].…”