Reduced Graphene Oxide (rGO) Doped Copper–Zinc (Cu–Zn) Nanocomposite Ferrites as an Efficient Material for High-Performance Thermoelectric Applications

Herein, we propose the synthesis of reduced graphene oxide (rGO) (0, 1.5, 2.5 and 3.5 wt%) doped Copper-Zinc (Cu-Zn) ferrite composites via simple solution combustion technique. The synergetic effects of rGO doping into Cu-Zn ferrite composites were examined through different analytical and spectroscopic characterization techniques such as scanning electron microscopy (SEM), powder X-ray diffraction (XRD) analysis, Fourier transform infra-red spectroscopy (FTIR), ultra-violet visible spectroscopy (UV-vis) and thermo gravimetric analysis (TGA). The average grain size of rGO doping into Cu-Zn ferrite composites was found to be 30 nm by SEM analysis, whereas the average crystallite size was found to be 35 nm. The energy band gap for Cu-Zn (3.5 wt%) composite was found to be 4.04 eV. The doping of rGO into the Cu-Zn ferrite enhances the electrical conductivity of ferrite from 19.74 S/m to 39.20 S/m due to improved charge carriers in the ferrite composite. The dielectric properties of the synthesized ferrite samples were significantly improved upon doping of rGO into the host Cu-Zn ferrite. The larger Seebeck coefficient and an improved electrical conductivity significantly affects the figure of merit (ZT) in doped ferrites composite. The ZT values for rGO doped Cu-Zn (3.5 wt%) composite was found to be 1.428 at 500 K. The rGO doped Cu-Zn (3.5 wt%) ferrite composite exhibit an enhanced thermo power factor from 27.56 µW/mK² to 492.91 µW/mK² which is approximately 18 times larger than that of pure Cu-Zn ferrite sample. Owing to improved electrical conductivity, dielectric properties, enhanced Seebeck coefficient and higher ZT of rGO doped Cu-Zn (3.5 wt%) ferrite composite emerges as potential material for the fabrication and development of electronic and thermoelectric devices which could be operated at room temperature.