Enhancing thermoelectric performance of a high-entropy titanate ceramic via multi-mechanism synergism driven by graphene oxide

This work addresses the degraded electrical conductivity in high-entropy thermoelectric ceramics—a consequence of entropy engineering—by introducing graphene oxide (GO) as a composite phase. Composites with varying GO content were prepared using spark plasma sintering. Performance characterization showed that the 1 wt% GO composite exhibited a ZT value of 0.32 at 1073 K, with an electrical conductivity of 10,800 S/m, a Seebeck coefficient of −210 μV/K, and a thermal conductivity of 1.59 W/(m·K). Heat treatment triggered structural evolution: the thermal decomposition of GO generated oxygen vacancies, thereby enhancing carrier concentration, and simultaneously introduced porous structures that further reduced thermal conductivity. Meanwhile, the undecomposed GO was reduced, forming a conductive network throughout the ceramic matrix. These multi-mechanism synergistic effects collectively contributed to the enhanced thermoelectric performance. This strategy demonstrates the potential of carbon-material integration for developing high-performance composite thermoelectric materials.