Engineering of Carbon-Oxide Composite Thermoelectric Nanomaterials

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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.