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Thermoelectric metal oxides with reduced graphene oxide
* 1 , 1 , 2 , 3 , 4 , 4 , 1
1  University of Aveiro, Aveiro, Portugal
2  Military University of Technology, Warsaw, Poland
3  Institute of Electronic Materials Technology (ITME), Warsaw, Poland
4  Technical University of Darmstadt, Germany
Academic Editor: Letizia De maria (registering DOI)

New power generation strategies based on clean and sustainable energy sources are needed due to the exponentially increasing energy demands of the world. Thermoelectric (TE) conversion of widely distributed waste heat can be proposed as an alternative route to convert thermal or solar energy into electric power economically.

Chalcogenides or skutterudites has higher figure of merit ZT in comparison to oxide materials but they are toxic and have high cost. At the same time, there is current interest for metal oxides as high-temperature TEs in the energy-harvesting sectors due to high chemical robustness and low toxicity. Driven by a need to improve TE performance of n-type oxides, ceramics and composites based on donor-doped SrTiO3 are considered as a promising material.

Within this context, SrTiO3 was doped by Nb was mixed with graphene oxide (GO) and conventionally sintered at high temperature in atmosphere of H2/N2 to reduce both Nb-doped SrTiO3 and GO. Addition of reduced GO (rGO) in combination with introduction of Sr vacancies provides a synergistic effect of fastening charge transport and thereby increasing electrical conductivity and suppressing the thermal conductivity. These factors, together with a moderate Seebeck coefficient, result in a high power factor PF ∼1.98 mW/(K2m) and ZT up to 0.29. Such findings offer further prospects for seeking high performance SrTiO3-based TEs by modification with rGO. Deep study of the influence of GO/rGO on other thermoelectric materials is done and present for wide auditory.

Keywords: thermoelectrics; graphene; figure of merit