Liquid-phase oxidation of toluene to benzaldehyde with molecular oxygen catalyzed by copper nanoparticles supported on graphene

Highly-dispersed copper nanoparticles (Cu NPs) were fabricated on the surface of reduced graphene oxide via direct hydrazine hydrate reduction of Cu²⁺ in aqueous solution. Scanning electron microscope and transmission electron microscope images show that the Cu NPs are distributed on the surface of graphene nanosheets, and the average particle size was about 40 nm. The Cu NPs supported on graphene have high reaction activity for the oxidation of toluene to corresponding benzaldehyde. It was found that the selectivity reached 66.5% and the conversion of toluene reached 11.5%.