Effectively photocatalytic aerobic oxidation of benzyl alcohol catalyzed by spinel Co–Ni ferrite under visible light irradiation

Magnetic ferrite Co _x Ni_1−x Fe₂O₄ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) nanocrystalline complex oxides were prepared by sol–gel auto-combustion method and well characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance UV–visible spectroscopy and N₂ adsorption–desorption analysis. The catalytic performances of the as-prepared samples were evaluated in photocatalytic oxidation of benzyl alcohol using molecular oxygen as oxidant under visible light irradiation. The results have shown that the catalysts exhibit remarkably high activities in the photocatalytic oxidation of benzyl alcohol. In particular, 18.9 % of benzyl alcohol conversion and 90.1 % of selectivity for benzaldehyde were obtained when the sample Co_0.3Ni_0.7Fe₂O₄ was used as catalyst under optimum conditions. The catalyst could be magnetically separated easily for reuse, and no obvious loss of activity was observed when reused in six consecutive runs.

Spinel Co–Ni ferrites were prepared by a facile, mild and environment-friendly route. The catalysts exhibit remarkably high activities in the photocatalytic oxidation of benzyl alcohol under visible light irradiation. The catalyst can be magnetically separated easily and has shown prominent recyclability.