Magnetic, Pseudocapacitive, and H 2 O 2 -Electrosensing Properties of Self-Assembled Superparamagnetic Co 0.3 Zn 0.7 Fe 2 O 4 with Enhanced Saturation Magnetization

The present work explores the structural, microstructural, optical, magnetic, and hyperfine properties of Co Zn Fe O microspheres, which have been synthesized by a novel template-free solvothermal method. Powder X-ray diffraction, electron microscopic, and Fourier transform infrared spectroscopic techniques were employed to thoroughly investigate the structural and microstructural properties of Co Zn Fe O microspheres. The results revealed that the microspheres (average diameter ∼121 nm) have been formed by self-assembly of nanoparticles with an average particle size of ∼12 nm. UV-vis diffuse reflectance spectroscopic and photoluminescence studies have been performed to study the optical properties of the sample. The studies indicate that Co Zn Fe O microspheres exhibit a lower band gap value and enhanced PL intensity compared to their nanoparticle counterpart. The outcomes of dc magnetic measurement and Mössbauer spectroscopic study confirm that the sample is ferrimagnetic in nature. The values of saturation magnetization are 76 and 116 emu g at 300 and 5 K, respectively, which are substantially larger than its nanosized counterpart. The infield Mössbauer spectroscopic study and Rietveld analysis of the PXRD pattern reveal that Fe ions have migrated from [B] to (A) sites resulting in the cation distribution: (Zn Fe ) [Zn Co Fe ] O . Comparison of electrochemical performance of the Co Zn Fe O microspheres to that of the Co Zn Fe O nanoparticles reveals that the former displays greater specific capacitance (149.13 F g ) than the latter (80.06 F g ) due to its self-assembled porous structure. Moreover, it was found that Co Zn Fe O microspheres possess a better electrochemical response toward H O sensing than Co Zn Fe O nanoparticles in a wide linear range.