Propylene oxide assisted sol–gel synthesis of zinc ferrite nanoparticles for solar fuel production

This paper reports the synthesis of phase-pure Zn-ferrite nanoparticles with high specific surface area (SSA) via the propylene oxide (PO) assisted sol–gel method. For the synthesis of Zn-ferrite, metal precursors (ZnCl2 and FeCl2·4H2O) were first dissolved in ethanol, and then PO was added dropwise for the gel formation. The effects of a variety of synthesis parameters, such as the concentration of PO, the gel aging time, the calcination temperature, and the calcination dwell time, on the phase/chemical composition, SSA, porosity, crystallite size, and morphology of the Zn-ferrite were studied in detail. Different analytical techniques, such as powder X-ray diffraction (PXRD), BET surface area analyzer (BET), electron dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HR-TEM), were used for analyzing the Zn-ferrite samples. The acquired results indicate that the phase/chemical composition of the Zn-ferrite remains unchanged, irrespective of the variation in the experimental conditions. BET analysis further confirms that the SSA of Zn-ferrite increased due to the increase in the concentration of PO and decreased with the upsurge in the calcination temperature and dwell time. The crystallite size of Zn-ferrite was also observed to be higher when the calcination temperature and dwell time were increased. SEM and HR-TEM assessment verify the formation of Zn-ferrite nanoparticles via the sol–gel method employed during the study.