The development of highly efficient catalysts for the selective oxidation of styrene to benzaldehyde has attracted great attention in recent years because of its significance in synthetic chemistry. In this study, two different kinds of copper-based metal oxide nanoparticles (NPs), namely, CuO and CuO/Co₃O₄ NPs, were synthesized by a simple and scalable method, and these nanoparticles demonstrated efficient catalytic abilities for the selective oxidation of styrene and its derivatives to the corresponding aldehydes in the presence of tert-butyl hydroperoxide (TBHP) under mild reaction conditions in excellent yields. Importantly, both of the heterogeneous catalysts can be recycled up to five runs while still maintaining their high catalytic activity.

Iron oxide coated platinum nanowires (Pt@Fe₂O₃ NWs) with a diameter of 2.8 nm have been prepared by the oxygen oxidation of FePt NWs in oleylamine. These “cable”-like NWs were characterised by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption fine structure analysis. These Pt@Fe₂O₃ NWs were used as “non-support” heterogeneous catalysts in oxidation of olefins and alcohols. The results revealed that it is an active and highly selective catalyst. Styrene derivatives were tested with molecular oxygen as the sole oxidant, with benzaldehyde successfully obtained from styrene in an absolute yield of 31 %, whereas the use of tert-butyl hydroperoxide as the sole oxidant in the oxidation of alcohols led to yields of more than 80 % of the corresponding ketone or aldehyde. This unsupported catalyst was found to be more active (TOF=96.5 h⁻¹) than other reported Fe₂O₃ nanoparticle catalysts and could be recycled multiple times without any notable decrease in activity. Our findings will extend the use of such nanomaterial catalysts to new catalytic systems.