A porphyrin-conjugated TiO2/CoFe2O4 nanostructure photocatalyst for the selective production of aldehydes under visible light

Abstract

We investigated the photocatalytic performance of a magnetic nanohybrid of CoFe₂O₄ and TiO₂ hetero-nanostructures (TiO₂/CoFe₂O₄) conjugated with zinc tetrakis carboxyphenyl porphyrin (ZnTCPP) for controlled oxidation of alcohols to aldehydes under visible light. The photocatalyst was prepared by nucleating titania on pre-formed CoFe₂O₄ nanoparticles, generating anatase TiO₂/CoFe₂O₄ hetero-nanostructures upon annealing at 450 °C. Then, they were conjugated with ZnTCPP resulting in ZnTCPP-TiO₂/CoFe₂O₄ nanohybrid materials, which were characterized in detail by different structural and spectroscopic methods. The ZnTCPP-TiO₂/CoFe₂O₄ nanostructures have an average size of 21 nm and show ferromagnetic behavior with a magnetization saturation of 47 emu g⁻¹, a remanence of 22 emu g⁻¹, and a coercivity of ca. 1000 Oe. The photocatalytic conversion of alcohols up to 87% under visible light was achieved by using this hybrid nanomaterial. Such a high catalytic performance can be related to the low charge recombination rate of the ZnTCPP-TiO₂/CoFe₂O₄ nanostructures. The magnetic hybrid nanostructures reported in this work have excellent potential as visible light photocatalysts with advantages of high efficiency, selectivity, stability, and easy separation.