Enhanced activity of Mg-Fe-O ferrites for two-step thermochemical CO2 splitting

•Mg-Fe-O ferrites with different mole fraction were used for two-step thermochemical CO2 splitting.•The self-regenerative property associated with sintering-resistance was conformed for the Mg-Fe-O ferrites.•The bulk redox species were involved into the redox reaction driven by the internal reaction.•The self-regenerative FM-0.2 with internal reaction yields 2.2 times more CO than FM-0.5.•A kinetic analysis corresponding to the bulk cation diffusion was established.