Effect of reduction condition on structure stability of NiFe2O4–δ and its catalytic performance of CO2 decomposition

Abstract Nickel ferrite, NiFe 2 O 4 , with spinel structure was prepared by citrate coordination method. The samples were characterized by X-ray diffraction (XRD) thermal gravimetric analysis (TGA). When the weight of NiFe 2 O 4 sample was 0.5 g, the optimum reduction condition for the preparation of oxygen-deficient nickel ferrite, NiFe 2 O 4–δ , reduced by H 2 was as follows: reduction temperature was 320°C, H 2 flow rate was 40 mL·min –1 and reduction time was 3 h. The results also showed that the higher reduction temperature and higher H 2 flow rate as well as longer reduction time led to an excessive reduction of NiFe 2 O 4–δ and the destructiveness of its spinel structure, resulting in the formation of Fe-Ni alloy Fe(Ni) as well as α-Fe phase.