Engineering of Carbon-Oxide Composite Thermoelectric Nanomaterials

对碳排放的日益关注导致了包括热电(TE)在内的替代、更环保和可持续技术的发展。TE装置是将热能转化为电能的固态能量转换器，适用于包括交通、核能和制造业在内的发电行业。传统TE材料的一个局限性是实现最高性能的温度范围非常窄，Bi2Te3的温度范围低至50℃，功率输出有限，效率相对较低，以及由于毒性而导致的成本和环境问题。如果要经济可靠地使用TE技术，材料需要在更宽的温度窗口内表现出高的TE效率。钛酸盐钙钛矿等氧化物由于其灵活的结构和高温稳定性是一种很有前途的TE材料，但目前它们的局限性是效率不高。然而，氧化物TES和碳纳米技术的集成有可能通过纳米结构和纳米尺度的带工程来提高性能。我们的研究愿景是通过将TE和碳纳米技术(如碳(石墨烯)或碳化物)集成到氧化物的微观结构中来增强氧化物的热电性能；这将产生碳-氧化物复合材料，并扩大工作温度范围。然而，只有当我们表征和控制降低导热系数所需的纳米结构以及提高导电率所需的界面结构和组成时，才能实现这些复合材料的工程化。我们的方法包括实验和建模，以实现以下目标：(1)利用一系列纳米结构来制备以钛酸锶、二氧化钛为基础的热电碳氧化物复合材料，以确定控制电和热传输的因素；(2)确定氧化物和碳之间的相互作用，从而提高性能；(3)建立目标微结构的原子模型，并表征其稳定性、拓扑结构、组成和电子结构。这项提议是与曼彻斯特和巴斯大学合作的一部分。这是新颖和及时的，因为它利用新的材料处理战略，使用多学科方法(建模/实验)来研究廉价和可持续能源生产的新兴技术。英国需要走在这一领域的前沿，因为日本、美国和欧洲确实在TE方面有重大计划。工作计划包括(1)目标材料：SrTiO3，TiO2陶瓷，(2)材料加工，(3)氧化物-石墨烯(即含石墨烯的La/SrTiO3)和氧化物-碳化物(TiC1-xox/TiOy)复合材料的微观结构控制，(4)常规X射线衍射和扫描电子显微镜的一般表征，(5)热电参数的测量，(6)界面和纳米结构的作用和生成的表征。

The growing concern over carbon emissions has led the development of alternative, greener and sustainable technologies including thermoelectrics (TE). TE devices are solid-state energy converters that transform thermal energy into electricity, applicable to power generation including transportation, nuclear, and manufacturing industries. A limitation of traditional TE materials is the very narrow temperature range for maximum performance, as low as 50C for Bi2Te3, limited power output, relatively low efficiency, the cost and environmental concerns due to toxicity. If TE technology is to be used economically and reliably, the materials need to exhibit high TE efficiency over a wider temperature window. Oxides, e.g. titanate perovskites, are promising TE materials because of their flexible structure and high temperature stability; their current limitations are the modest efficiency. However, integration of oxide TEs and carbon nanotechnologies has the prospect of enhancing performance, via nanostructuring and band engineering at the nanoscale. Our research vision is to enhance thermoelectric properties of oxides by integrating TE and carbon nanotechnologies, as either carbon (graphene) or carbide, into the oxide microstructure; this will generate carbon-oxide composites and extend the range of operating temperatures. However, the engineering of these composites can only be achieved if we characterize and control both the nanostructuring needed for reduced thermal conductivity, and the interface structures and compositions needed for increased electrical conductivity. Our approach involves experiments and modelling to achieve the following objectives: (1) to fabricate thermoelectrics carbon-oxide composites based on SrTiO3, TiO2, with a range of nanostructures to determine the factors controlling electric and thermal transport; (2) to identify the interactions between oxides and carbon that lead to enhanced performance; (3) to produce atomistic models of target microstructures, and to characterize their stability, topology, composition and electronic structure. This proposal is part of a collaboration with the University of Manchester and Bath. It is novel and timely because exploits novel material processing strategies using a multidisciplinary approach (modelling/experiments) to study emerging technologies for cheap and sustainable energy generation. The UK needs to be at the forefront of this field as there are indeed major programmes in TE in Japan, USA, and Europe.The work programme covers (1) target materials: SrTiO3, TiO2 ceramics, (2) materials processing, (3) microstructural control of oxide-graphene (i.e. La/SrTiO3 with graphene) and oxide-carbide (TiC1-xOx/TiOy) composites, (4) general characterization with routine XRD and SEM, (5) measurements of thermoelectric parameters, (6) characterization of the role and generation of interfaces and nanostructures.