Enhanced photocatalytic and electrochemical properties of Cu doped NiMnFe2O4 nanoparticles synthesized via probe sonication method

A series of copper (X) doped NiMnFe2O4 (X = 0.1, 0.2, 0.3, 0.4) nanoparticles (NPs) were synthesized using a simple and effective probe sonication method. The obtained NPs were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible studies. The photocatalytic degradation activity of Ni0.2CuxMn0.2Fe2O4 (x = 0.1, 0.2, 0.3, 0.4) NPs were evaluated by degrading methylene blue (MB) and Drimarene yellow (DY) dyes under UV light. The removal efficiencies of 70.2% and 43.3% by NPs with X = 0.1 was observed for MB and DY, respectively. While NPs with X = 0.4 displayed removal efficiencies of 98.1% for MB and 28.9% for DY. The effect of dopant concentration and pH on the photocatalytic ability of the NPs was studied in detail. Electrochemical measurements were performed for the NPs using Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) using a carbon paste electrode in acidic (0.1 M HCl) and alkaline (0.1 M NaOH) electrolytes. The specific capacitance values for electrodes with X = 0.1 and 0.4 M were calculated as 244.5 and 498.6 F g(-1) in 0.1 M HCl; 40.14 and 25.01 F g(-1) in 0.1 M NaOH at a scan rate of 10 mV/s, respectively. EIS measurements further confirmed the CV results. The impedance spectrum of electrode with X = 0.4 in 0.1 M HCl displayed a lowered arc with a smaller diameter in the region of high frequency, revealing the low charge transfer resistance (R-Ct = 5.281 Omega) and high capacitance (C = 1.654 x 10(-8) F) of the electrode. The high reversibility of electrodes and remarkable photocatalytic activity makes them favourable for applications in multifunctional fields.