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Thermoelectric materials can convert waste heat directly into electricity. Tommi Tynell, who is a doctoral candidate at the Aalt

admin2022-09-18  18
问题     Thermoelectric materials can convert waste heat directly into electricity. Tommi Tynell, who is a doctoral candidate at the Aalto University School of Chemical Technology, has developed hybrid (混合的) thermoelectric materials which combine useful properties from different types of materials.
    He found that by adding organic layers between layers of zinc it is possible to improve the performance of thermoelectric materials. The organic layers are also believed to have a major effect in reducing thermal conductivity, which would be very useful in thermoelectric materials.
    Developing more efficient thermoelectric materials is a major challenge, because the physical properties that affect the performance of the materials are not independent of each other. The optimization of a material is very difficult, because as you improve one feature, other properties may deteriorate at the same time.
    The biggest obstacle to the broad utilization of thermoelectric generators is the low efficiency of currently known thermoelectric materials. In addition, the best existing compounds do not withstand the high temperatures required and often contain rare and harmful elements.
    In his research, Tynell added layer upon layer of nanoscale structures, examining their formation using X-ray and infrared (红外线的) devices. In the research, thin films of zinc oxide were used, because zinc oxide is one of the most promising thermoelectric oxide materials. Oxide materials are environmentally friendly and their availability is not a problem. It is believed that they will play an important role in the future development of sustainable energy technologies.
    Tynell combined atomic layer deposition and molecular layer deposition and thus succeeded in manufacturing a hybrid superlattice (超晶格) composed of organic and inorganic compounds. Atomic layer deposition is an extremely accurately controlled nanofabrication process. The process was used to produce layered nanostructures, with extremely thin organic layers alternating with thicker inorganic layers. Three different source materials were used for the organic substance: hydroquinone, 4-aminophenol and 4,4’-oxydianiline. All of the organic molecules tested were found to influence the thermoelectric properties of the thin zinc oxide film.
    Although the structures of the starting materials were quite similar, the size of the effect was quite variable depending on the source material. Hydroquinone (对苯二酚) was the most applicable of the three, because it formed the desired structures most easily.
    Tommi Tynell did his doctoral thesis in Academy Professor Maarit Karppinen’s research group. The research of the group is unique in that it is rare to use hybrid materials in thermoelectric research. Only a few research groups in the world are currently focused on investigating the properties of hybrid materials. By utilizing thermoelectric energy harvesting it will be possible to reduce our dependence on traditional energy sources.
Why is it so challenging to develop more efficient thermoelectric materials?
选项 A、Because it is difficult to develop the technique used in the process.
B、Because it will cost a large sum of money, with no special funds.
C、Because the physical characteristics of a material are relevant.
D、Because the features of a material cannot be easily changed.
答案C
解析 细节题。根据题干中的develop more efficient thermoelectric materials可定位到原文第三段第一句。该句提到，如何才能制造出更加高效的热电材料是个重大挑战，因为影响热电材料效果的物理特性之间并不是相互独立的。关键信息是not independent，由此可知，C选项符合，而A、B两项未提到，D项的说法正好与原文相反，故选C。
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