Recycled carbon fibre/Bi2Te3 and Bi2S3 hybrid composite doped with MWCNTs for thermoelectric applications

In this study, a cost-effective thermoelectric generator was developed from recycled carbon fibre (RCF) composites incorporated with multi-walled carbon nanotubes (MWCNT) doped bismuth telluride (Bi2Te3) and bismuth sulphide (Bi2S3). A facile approach utilising hot compression and brushing was used to prepare a cost-effective inorganic RCF thermoelectric composite with varying content of MWCNT ranging from 0.05 to 0.20 wt%. This work investigated the effect of doping MWCNT in Bi2Te3 and Bi2S3 matrix and its corresponding effect on thermoelectric, morphological, structural and thermal properties of RCF thermoelectric composite. The thermoelectric properties of RCF composites were optimised at 0.10 wt % (1.044 μW K−2m−1) and 0.15 wt% (0.849 μW K−2m−1) of MWCNT for doped Bi2Te3 and Bi2S3 respectively. The addition of MWCNT reduced the difference in power factor between RCF-Bi2Te3 and RCF-Bi2S3 from 52% to 19%. The presence of MWCNT in the Bi2S3 matrix overcame the high resistivity of Bi2S3 and improved its thermoelectric properties as MWCNT provided a conductive pathway for efficient electron transfer. Thus, MWCNT doped Bi2S3 RCF composites is an alternative to telluride free thermoelectric generators.