二碲化钨纳米带的合成及热电性质

在能源短缺和环境污染日益严重的今天,为了减少温室气体排放,提高能源利用效率,可再生能源转换技术的研究就显得十分必要.热电材料是一类绿色无污染的能源转换材料,将在工业废热利用以及太阳光热复合发电等方面发挥重要作用,因而受到人们越来越多的关注.本文通过化学气相沉积法(CVD)合成了二碲化钨(WTe2)纳米带用于研究其热电性质.扫描电子显微镜和透射电子显微镜分别证实了生长在Si衬底上的大面积WTe_2样品具有高质量的带状纳米结构,选区电子衍射表明样品具有单晶相.并在大约300–652 K的温度范围内研究了退火后纳米带的热电输运性质,研究结果表明纳米带的最大电导率约为9.55×10~4S/m,最大塞贝克系数为90μV K^-1.特别是退火后纳米带样品的最大功率因子相较于普通粉末样品提高了近2倍.这是因为一维单晶纳米带结构具有较少的缺陷,导致了载流子迁移率提高,从而导致了高的电导率.粉末样品具有较多的缺陷,禁带宽度较小,导致了激发载流子所需要的激发能较小,单位温度变化而产生的载流子浓度较大,从而导致了低的塞贝克系数.因此WTe_2纳米带可以用于制造具有价廉和环境友好的热电纳米器件的优异材料.

Synthesis and thermoelectric properties of tungsten telluride nanobelts

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 about90μV 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.