Enhanced thermoelectric power factor of graphene-Ba-Co-O composites via interfacial charge transport

Cobalt oxide based thermoelectric have attracted attention due to their high thermal stability and relatively large thermopower at room temperature. However their practical applications are limited by low electrical conductivity, which hindered the thermoelectrical power factor. In present study, the structural and thermoelectric properties of cobalt oxide-based materials systematically investigated through compositional tuning and graphene incorporation. Initially, Na-Co-O compound with different sodium content were synthesized to examine the influence of cation stoichiometry on structural and transport properties. To further modify lattice structure, alkaline earth elements (Ca, Sr and Ba) were introduced into cobalt oxide and structural analysis suggesting that lattice distortion due to the difference in ionic radii. Among all, Ba-based cobalt oxide composition exhibits relatively higher electrical conductivity by maintain thermopower. To overcome intrinsic electrical conductivity, graphene has been added into the Ba 0.33 CoO 2 . These composite exhibited enhancement of thermoelectric power factor of 894 µW/mK 2 at room temperature. This enhancement is attributed to the formation of graphene conductive network and additional phonon scattering sites within the composites, which may help to break the interrelation between thermopower and electrical conductivity. These results highlighting the effectiveness of interfacial transport engineering in cobalt oxide thermoelectric materials.