Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Abstract

Perspectives concerning the two‐step thermochemical CO2 splitting via NiFe2O4‐based materials are given for CO production. The thermochemical reactivity of these materials is investigated, and the nature of reaction process is discussed. NiFe2O4/MgO exhibits universally better performance, giving 3–10 times higher CO production than that of two other materials, NiFe2O4/SiO2 and NiFe2O4/ZrO2. A comprehensive analysis indicates that the spinel ferrites in NiFe2O4/MgO can dissolve in and exsolve out of the wüstite matrix in synchronization with the temperature swing, leading to the self‐regeneration of spinel ferrites, which alleviates the sintering of NiFe2O4/MgO. Meanwhile, a similar dynamic transition between spinel and wüstite occurs under the periodic variation between reductive and oxidative atmospheres, associated with the internal reaction that promotes the interior iron diffusion, which plays a critical role in enhancing the reactivity of NiFe2O4/MgO.