Solar-driven thermochemical redox cycles of ZrO2 supported NiFe2O4 for CO2 reduction into chemical energy

In this study, solar thermal power coupled with a direct irradiated solar thermochemical reactor using porous-medium NiFe2O4@ZrO2 oxygen exchange material was investigated by combining experiments to the numerical models. The ability of ZrO2, NiFe2O4, and NiFe2O4@ZrO2 to release/uptake O2 and their CO2-splitting characteristics are analyzed by the thermogravimetric analyzer (TGA) and the microstructural changes and chemical composition of NiFe2O4@ZrO2 are examined by scanning electron microscopy (SEM) and x-ray energy dispersive spectrometer (EDS). The experiment performed with a redox thermochemical reactor under a high-flux solar spectrum resulted in a total of 337.89 mL of CO collected during 46 min of CO2-splitting over NiFe2O4@ZrO2 redox material. Higher CO2-splitting activity of NiFe2O4 resulting in 186.545 μmol/g and 130.707 μmol/g of CO yield at 1293-795 °C and 100 sccm of CO2 flow rate were obtained by TGA at the first and second cycle, respectively. The results of both experiments showed significant CO yield at the early stages of oxygen carriers’ re-oxidation with CO2. This study provided important results that could have significant contributions to the solar thermochemical energy storage and CO2 chemical transformation processes.