Synergistic Enhancement of Electrical Conductivity and Thermoelectric Efficiency in ZnFe2O4─Fe2O3/Graphene Composites

Abstract

This work demonstrates the successful improvement in the thermoelectric properties of the spinel ZnFe2O4 (ZFO) composite with multilayer graphene. Phase‐pure ZFO prepared using the sol–gel method was mixed with multilayer graphene, compacted, and sintered at 1200 °C for 5 h in an N2 atmosphere. A significant increment in electrical conductivity from 6.3 S/m of bare ZFO to 1069 S/m at 750 K was achieved for the 7.5 wt% graphene‐incorporated ZnFe2O4─Fe2O3 composite. This is because of the weakening of the double Schottky barrier and effective utilization of charge carriers trapped at the grain boundaries. The enhanced thermoelectric performance with a zT of 0.008 at 673 K is obtained for a 5 wt% graphene‐incorporated ZnFe2O4─Fe2O3 composite due to its low thermal conductivity. The effective reinforcement of graphene with ZFO and also the presence of Fe2O3 as secondary phase make the composite a promising material with improved thermoelectric performance and heat conversion efficiency for high‐temperature thermoelectric applications.