Sol–gel derived CeO2–Fe2O3 nanoparticles: Synthesis, characterization and solar thermochemical application

Abstract

Synthesis of CeO2–Fe2O3 nanoparticles via propylene oxide (PO) aided sol–gel method for the production of solar fuels via thermochemical H2O/CO2 splitting cycles is reported in this paper. For the synthesis of CeO2–Fe2O3, cerium nitrate hexahydrate and iron nitrate nonahydrate were first dissolved in ethanol and then PO was added to this mixture as a proton scavenger to achieve the gel formation. Synthesized CeO2–Fe2O3 gel was aged, dried, and then calcined in air to achieve the desired phase composition. Influence of different synthesis parameters on physico-chemical properties of sol-gel derived CeO2–Fe2O3 was explored in detail by using various analytical methods such as powder x-ray diffraction (PXRD), BET surface area analyzer (BET), x-ray energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HR–TEM). According to the findings, at all experimental conditions, phase/chemical composition of sol–gel derived CeO2–Fe2O3 was observed to be unaltered. The SSA and pore volume was increased with the upsurge in the amount of PO used during sol–gel synthesis and decreased with the rise in the calcination temperature and dwell time. In contrast, the crystallite size was enlarged with the increase in the calcination temperature and dwell time. The nanoparticle morphology of the sol–gel derived CeO2–Fe2O3 was verified with the help of SEM/TEM analysis. Thermochemical CO production ability of sol–gel derived CeO2–Fe2O3 was investigated by performing thermogravimetric thermal reduction and CO2 splitting experiments in the temperature range of 1000–1400°C. Reported results indicate that the sol–gel derived CeO2–Fe2O3 produced higher amounts of O2 (69.134μmol/g) and CO (124.013μmol/g) as compared to previously investigated CeO2 and CeO2–Fe2O3 in multiple thermochemical cycles. It was also observed that the redox reactivity and thermal stability of sol–gel derived CeO2–Fe2O3 remained unchanged as it produced constant amounts of O2 and CO in eight successive thermochemical cycles.