Donor doped SrTiO₃ based perovskites are considered as very promising candidates for high temperature thermoelectric applications, but the figure of merit (ZT) of these n-type oxide thermoelectrics need to be enhanced for making it commercially viable. However, it is challenging to improve the transport properties of these oxides in order to achieve high ZT. Here we put forward a strategy of boosting the electron transport by inducing semiconductor to metal transition in Nb doped SrTiO₃ (STN) by formation of nanocomposites with graphene oxide (GO). We could enhance electrical conductivity remarkably by gradual incorporation of GO in the matrix of STN, which changed its semiconductor (dσ/dT>0) behavior into metallic (dσ/dT<0) for more than 1 wt% GO content. GO sheets embedded in the grain boundaries of polycrystalline STN facilitated electron transport without increasing much it's thermal conductivity, resulting in the order of magnitude increase in the ratio of electrical conductivity and thermal conductivity in the temperature range from 300 K to 1200 K. Hence, ZT of STN ceramics was raised by 50 times due to GO incorporation. Maximum ZT of 0.5 was attained at 1200K in n-type bulk oxide nanocomposite made of environmentally benign, earth-abundant elements.

供体掺杂的基于SrTiO ₃的钙钛矿被认为是高温热电应用中非常有前途的候选材料，但是这些n型氧化物热电材料的品质因数（ZT）需要提高才能使其在商业上可行。然而，为了实现高ZT，改善这些氧化物的传输性质是挑战性的。在这里，我们提出了一种通过在Nb掺杂SrTiO _3中诱导半导体向金属过渡来促进电子传输的策略。（STN）通过与氧化石墨烯（GO）形成纳米复合材料来实现。我们可以通过在STN基质中逐步掺入GO来显着提高电导率，从而将GO含量超过1 wt％时其半导体（dσ/ dT> 0）行为改变为金属（dσ/ dT <0）。嵌入多晶STN晶界中的GO薄层促进了电子传输，而没有增加其热导率，从而导致在300 K至1200 K的温度范围内，电导率和热导率之比增加了一个数量级。由于掺入GO，STN陶瓷的数量提高了50倍。在由环境无害的，富含地球的元素制成的n型本体氧化物纳米复合材料中，在1200K时，最大ZT为0.5。