Sol-gel synthesized NixFe3−xO4 for thermochemical conversion of CO2

Abstract To identify the best suitable metal oxide (MO) to split H2O/CO2, it is critical to investigate the formation of O2 vacancies during thermal reduction (TR) step and the re-oxidation of the MOs via H2O or CO2 splitting (CS) reaction. Accordingly, in the present work, we have experimentally evaluated the redox reactivity of sol-gel synthesized Ni-ferrite (NiF) in multiple temperature-swing redox cycles. The calcined powders of NiF materials were characterized for the determination of phase purity, crystallite size, and particle morphology. In case of the TGA cycles, the TR was accomplished at 1400 °C (for 60 min) and the reduced NiF was again re-oxidized via CS reaction at 1000 °C (for 30 min). The obtained outcomes indicated that, among all the NiF materials investigated i.e. Ni0.2Fe2.8O4 (NiF2), Ni0.4Fe2.6O4 (NiF4), Ni0.5Fe2.5O4 (NiF5), Ni0.6Fe2.4O4 (NiF6), Ni0.8Fe2.2O4 (NiF8), NiFe2O4 (NiF10), the NF10 has the aptitude to produce maximum quantities of O2 (nO2) and CO (nCO). When compared with the benchmark CeO2 material, the average nO2 and nCO by the NiF10 (from cycle 2 to cycle 9) was greater by 15.9 μmol/g·cycle and 30.9 μmol/g·cycle, respectively.