Flexible thermoelectric films from electrodeposited Bi₂Te₃ on recycled carbon fibre-Modulation of Seebeck coefficient by electrode pre-treatment

Recycled carbon fibre (RCF) sheets were electrodeposited with bismuth telluride (Bi2Te3), a state-of-art thermoelectric compound, to produce an n-type thermoelectric module which serves as a precursor to the development of a flexible thermoelectric module. The primary objective of this study is to determine the effects of electrode pre-treatment on the Seebeck coefficient and surface morphology of the RCF electrode. The RCF electrode pre-treatment methods include solvent cleaning via isopropanol, electrochemical polarization using phosphate buffer solution (PBS), and thermal annealing at 350°C with 5% hydrogen in argon gas. The main thermoelectric property, the Seebeck coefficient, which is a measure of the magnitude of an induced thermoelectric voltage due to the thermal gradient across the material, is reported. The surface morphologies and elemental composition of the post-electrodeposited carbon fibres were also studied and reported by Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDX). Electrochemical polarization method yielded -13.38 μV/K in Seebeck coefficient compared to -12.23 μV/K of control sample. Solvent cleaned and heat treated samples have lower Seebeck coefficient values of -10.70 μV/K and -10.71 μV/K respectively compared to control sample. SEM images show promising surface properties improvement of the electrodeposited RCF which have been subjected to pre-treatment.