Abstract:
The electrochemical and enhanced thermoelectric properties of pristine Bi₂Te₃ and Bi₂Te₃/reduced graphene oxide (Bi₂Te₃ + rGO) composites at 1%, 3% and 5% levels of rGO were synthesized via a simple ultrasonic method. The X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UVvis spectrometry (UV vis) and their electrochemical and thermoelectric properties were measured. The ultrasonic method succeeded in producing rGO nanosheets composited with Bi2Te3 forming grain boundary interfaces of rGO with Bi₂Te₃. The resulting samples displayed a continuous network structure of rGO nanosheets in Bi₂Te₃ + rGO composites for electrons in the conduction band of the Bi₂Te₃ structure. Electrons were transferred to rGO nanosheets at the interface, contributing electron charge carriers in Bi₂Te₃ + rGO composites. This indicates band alignment between Bi₂Te₃ and rGO nanosheets. The Bi₂Te₃ + rGO composites exhibited an increasing storage charge mechanism of electrical double layer capacitors with greater rGO contents. The Bi₂Te₃ + rGO composites displayed negative a Seebeck coefficient for thermoelectric materials. The highest ZT value was 0.17 in the bulk 1% Bi₂Te₃ + rGO composite. Improved electrochemical and thermoelectric properties of the Bi₂Te₃ + rGO 1% composite resulted from the interaction of the grain boundary interfaces of rGO nanosheets with pristine Bi₂Te₃ following the model of band alignment between Bi₂Te₃ and rGO nanosheets.