Synthesis and thermoelectric properties of tungstentelluride nanobelts

Abstract

Energy shortage and environmental pollution are getting worse today, researching on renewable energy conversion technology is necessary to reduce greenhouse gas emissions and improve energy efficiency. Thermoelectric materials are a class of green, non-polluting energy conversion materials, which jn ln will play an important role in the utilization of industrial waste heat and solar thermal composite power generation, so they have attracted more and more attention. In this paper, tungsten telluride (WTe2) nanobelts (NBs) were synthesized by chemical vapor deposition (CVD) for study of their thermoelectric transport properties. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) respectively confirm that large-scale WTe2 NBs grown on Si substrates have high quality belt-like nanostructures. Selected area electron diffraction (SAED) shows that WTe2 NBs have a single crystal phase. The thermoelectric transport properties of NBs samples after annealing samples are measured at the temperature range from ~300 to ~652 K. The results proved that the best electrical conductivity is about 9.55×104 S/m and the maximum Seebeck coefficient is about 90 µV K−1. Especially, the maximum power factor of the NBs samples after annealing are nearly twice that of the conventional powders (CPs) samples. The one-dimensional single crystal nanobelt structure has fewer defects, and higher carrier mobility result in higher conductivity, The CPs samples have more defects, small forbidden band width result in low excitation energy, the number of carriers generated in the range of unit temperature variation is large, which result in a low Seebeck coefficient. So WTe2 NBs may be suggested as excellent materials for fabrication of thermoelectric nanodevices with inexpensive and environment friendly.