The peak position and FWHM from XRD data were used to calculate the average crystallite size for ZnFe2O4, PNZF, Fe2O3, PNF, ZnO, and PNZ, which were found to be 21.51 nm, 25.34 nm, 29.42 nm, 27.2 nm, 33.19 nm, and 24.7 nm, respectively. The chemical structure and functional groups of metal oxides, PN, and its composites were investigated by FTIR analyses. The FTIR spectra of pure PN and its composites show clear characteristic peaks (Table ). For example, the peak at 3260 cm -1 corresponds to the N-H bond stretching vibrations in the PN polymer chain (Figure ) . In addition, a notable and relatively The FTIR spectra of the metal oxides (see Figure ) explain the structural features of the corresponding metal oxides. The bands at 720, 950, and 1060 cm -1 can be assigned to ZnO, Fe2O3, and ZnFe2O4, respectively. A broad band at 3500 cm -1 , present in the FTIR spectra of all metal oxides, is due to OH stretching. This band illustrates the porous nature of the metal oxides, which contain moisture in the pores of the metal oxides . This peak is more pronounced and broader in the spectrum of ZnO, indicating a higher water content than other metal oxides. To summarize, the FTIR spectra of metal oxides differ overall from those of PN and PN composites. The UV-vis spectra of PN and PN composites reveal three characteristic peaks. The first peak in the range of 720-800 nm is attributed to the creation of excitons that cause the bipolaron transition . The bipolaron transition in PNZF was observed at 750 nm, while for PNZ and PNF, it was observed at 680 nm and 800 nm, respectively. The second peak in the range of 380-430 nm represents the polaron transition of quinoid rings present in PN as well as in composites . The relatively higher intensity absorbance peaks observed in the range of 280-300 nm represent the ππ* transition of the aromatic/benzoid rings of composites and pure PN . Specifically, for PNZF, this peak was observed at 280 nm, while for PNF and PNZ, it was observed at 300 nm and 290 nm, respectively. On the other hand, the UV-Vis spectra of metal oxides showed a single and characteristic absorption peak in the range of 270-320 nm. The absence of extra peaks implies the purity and wellcrystalline nature of the metal oxides . This single prominent and characteristic absorption peak was observed at 270 nm for ZnO, 320 nm for Fe2O3, and at 380 nm for ZnFe2O4 . The shifting of peak position is related to bathochromic shift, which was a reason for selecting bimetal oxides to synthesize an imminent composite electrode material for future supercapacitors.