Study on the Catalytic Reduction Performance of Mg-Doped NiFe₂O₄ Ferrite for CO₂ by Adopting the Co-Precipitation Method

Spinel ferrites offer a versatile platform for high-temperature CO₂ conversion, yet simultaneously achieving strong adsorption/activation and long-cycle thermal stability remains challenging. Here, we tailor the defect chemistry and microstructure of NiFe₂O₄ through low-level A/B-site modification by partially substituting Ni with Mg (Ni_0.96Mg_0.04Fe₂O₄). The catalyst was synthesized by Mg doping and characterized comprehensively by ICP, XRD, SEM and CO₂-TPD, followed by evaluation of CO₂ adsorption and thermal decomposition activity under cyclic operation. Mg incorporation suppresses grain coarsening, refines crystallites, increases accessible surface area and reduces particle size, thereby improving resistance to thermal aging. The enriched oxygen-vacancy population enhances oxygen storage and strengthens CO₂ adsorption, which translates into higher catalytic utilization of active sites. Under repeated CO₂ decomposition cycles, the Mg-modified ferrite shows markedly improved stability and service life, achieving a carbon deposition of 19.62%. The combined evidence indicates that Mg substitution stabilizes the spinel lattice against sintering while promoting vacancy-assisted CO₂ activation, providing a simple and cost-effective compositional lever to balance activity and durability for high-temperature CO₂-to-carbon conversion.