Intercalation to Enhance the Thermoelectric Properties of Ca3Co4O9 Composites through BiCuSeO Nanosheets

Abstract

Ca3Co4O9-based thermoelectric ceramics are recognized as promising candidates for medium-to-high temperature waste heat recovery, yet practical applications are restricted by an insufficient average ZT (ZTave). Herein, BPCCSO (Bi0.88Pb0.06Ca0.06CuSeO) nanosheets were introduced into the CCO-rGO (Ca2.96Co4O9-rGO) matrix via a coshear-exfoliation method. The microstructures, electrical properties, and thermal properties of the resulting composites were systematically investigated as a function of BPCCSO nanosheet content. Upon the incorporation of BPCCSO nanosheets, the charge carrier concentration was increased from 2.4 × 1019 to 2.6 × 1020 cm–3 at 300 K. At 873 K, an electrical conductivity of 135.2 S/cm and a Seebeck coefficient of 193 μV/K were exhibited by the CCO-rGO-15 wt % BPCCSO composites. Consequently, a peak ZT value of 0.31 was achieved at 873 K, and a high ZTave of approximately 0.15 was attained over the temperature range of 300–873 K. Such an intercalation engineering strategy synergistically optimizes electron–phonon transport in oxide thermoelectrics, thereby enhancing the efficiency of waste heat recovery.