Self-assembled porous nano-composite with high catalytic performance by reduction of tetragonal spinel CuFe₂O₄

A tetragonal spinel CuFe₂O₄ reduced in H₂ flow at 633 K shows a self-assembled microstructure that exhibits fine dispersion of copper nanoparticles within the porous Fe₃O₄ matrix and high catalytic performance. Sintering of copper particles was inhibited significantly even after H₂ reduction at 873 K when CuFe₂O₄ was used as a precursor, while it readily occurred for CuO and physically mixed CuO + Fe₂O₃. The high thermal stability of copper nanoparticles from the CuFe₂O₄ after H₂ reduction is ascribed to the immiscible interaction between copper and iron (or iron oxides). The spinel CuFe₂O₄ can be regenerated after an intentional sintering treatment (e.g., in H₂ at 873 K) by calcinations in air at 1273 K where the activity and the morphology restored completely. We show that metallurgical knowledge is available to tailor microstructure for designing catalysts.