Similarly, for the deposition of Fe2O3 and ZnFe2O4 particles, -0.7 V and -0.9 V were applied for 600 s to obtain PN@Fe2O3 (PNF) and PN@ZnFe2O4 (PNFZ). The electrodeposition process was repeated three times to obtain a fully covered electrode. Alternatively, the same results were obtained, using cyclic voltammetry for the electro-deposition. Thereby, it was cycled in the respective potential range for 5 cycles with a scan rate of 50 mV s -1 . The composites were thoroughly washed with distilled water and acetone afterward and dried in all syntheses.