Wei Jian, Wang Yuan, Li Xueting, Jia Zhaoyang, Qiao Shishuai, Jiang Yichang, Zhou Yuqi, Miao Zhuang, Gao Dongming, Zhang Hao
College of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):3919-3929. doi: 10.1021/acsami.0c18863. Epub 2021 Jan 12.
In recent years, the problem of overheating in summer has been of great concern. Pavements are continuously exposed to solar radiation, and because of high temperatures, pavement temperatures reach 60 to 70 °C. This potential low-grade heat has been unused. Cement-based composites with thermoelectric properties can convert this low-grade heat to useful electrical energy. The importance of this green technology for generating renewable energy and sustainable development has been widely accepted and noticed. However, the power factor of current cement-based composites is too low, and harvesting low-grade heat on a large scale and at low cost requires improving the thermoelectric properties of cement-based composites. In this paper, we present a method to increase the electrical conductivity of ZnO and thus improve the thermoelectric properties of cement-based composites by defect engineering, obtaining a high power factor of 224 μWm K at 70 °C, a record value recently reported for thermoelectric cement-based composites. Zinc oxide powder was treated with a reducing atmosphere to increase the content of oxygen defects and thus improve the electrical conductivity. Pretreated ZnO powder of 5.0 and 10.0 wt % expanded graphite were added to the cement matrix. The ZnO/expanded graphite cement-based composites were made and tested for their thermoelectric properties using a dry pressing process, which exhibited excellent thermoelectric properties. The result showed high conductivity (12.78 S·cm), a high Seebeck coefficient (-419 μV/°C), a high power factor (224 μWm K), and a high figure of merit value (8.7 × 10), which facilitate future large-scale applications. Using the cement-based composites to lay a road of 1 km in length and 10 m in width, 35.2 kW·h of electricity can be collected in 8 h. This study will inspire how to improve thermoelectric performance of cement-based composites.
近年来，夏季过热问题备受关注。路面持续受到太阳辐射，由于温度较高，路面温度可达60至70摄氏度。这种潜在的低品位热能一直未被利用。具有热电性能的水泥基复合材料可将这种低品位热能转化为有用的电能。这种绿色能源生产和可持续发展技术的重要性已得到广泛认可和关注。然而，目前水泥基复合材料的功率因数过低，要大规模、低成本地收集低品位热能，需要提高水泥基复合材料的热电性能。本文提出一种通过缺陷工程提高氧化锌电导率从而改善水泥基复合材料热电性能的方法，在70摄氏度时获得了224微瓦每米开尔文的高功率因数，这是近期报道的热电水泥基复合材料的最高值。用还原气氛处理氧化锌粉末以增加氧缺陷含量，从而提高电导率。将5.0重量百分比和10.0重量百分比的经预处理的氧化锌粉末与膨胀石墨加入水泥基体中。制备了氧化锌/膨胀石墨水泥基复合材料，并采用干压工艺测试其热电性能，该复合材料表现出优异的热电性能。结果显示其具有高电导率（12.78西门子每厘米）、高塞贝克系数（-419微伏每摄氏度）、高功率因数（224微瓦每米开尔文）和高优值系数（8.7×10），这有利于未来的大规模应用。使用这种水泥基复合材料铺设一条长1公里、宽10米的道路，8小时内可收集35.2千瓦时的电能。本研究将为如何提高水泥基复合材料的热电性能提供启发。
