Evaluation of thermoelectric properties of hybrid polyaniline nanocomposites incorporated with graphene oxide and zinc oxide with different morphologies

Abstract

Thermoelectric materials have been the object of interest in energy demand, given their potential for heat capture and the possibility of conversion into electricity. Among the possible thermoelectric materials, polymeric ones have been investigated because they are durable, non-toxic, and reproducible. This work used polyaniline (PANI), a good conductivity polymer, as a matrix to prepare hybrid nanocomposites. Nanoparticles were incorporated into the PANI matrix via solution with m-cresol. Two types of novel nanoparticles were used: zinc oxide (ZnO) synthesized with morphologies of nanoneedles (n-ZnO) and nanoflowers (f-ZnO). Hybrids of graphene oxide (GO) and ZnO with these morphologies (GO/n–ZnO and GO/f–ZnO) were incorporated into the hybrid PANI nanocomposites. Thermal stability was evaluated by thermogravimetric analysis (TGA). An improvement in thermal stability was observed with increasing GO/ZnO nanoparticles, as well as a higher degradation of the polymer matrix for higher levels of ZnO nanoparticles. The absorption bands of nanoparticles and PANI were observed by Fourier infrared spectroscopy (FT-IR). The corresponding characteristic bands of the functional groups were well evidenced, reflecting the success in synthesizing thermoelectric nanocomposites. Those with hybrid nanoparticles (GO/ZnO) had higher values of electrical conductivity (10.8 and 10.5 S cm−1), while those with only ZnO nanoparticles had higher Seebeck coefficient values (166.4 and 67.4 μV K−1). The only one with the highest thermoelectric force factor was PANI/GO/n-ZnO, with a value of 14.79 μW m−1 K−2, which is 49.3 times greater than the pure polymer and 1.5 times greater than the PANI/n-ZnO nanocomposite.