Strong metal-support interaction induced O2 activation over Au/MNb2O6 (M = Zn2+, Ni2+ and Co2+) for efficient photocatalytic benzyl alcohol oxidative esterification

Abstract

A series of metal niobates (MNb2O6, M = Zn2+, Ni2+ and Co2+) were prepared from H-niobate precursor under hydrothermal conditions, in which amino groups of l-lysine play an important role. Au nanoparticles were then supported on these niobates by NaBH4 reduction method. More importantly, the strong interaction between Au nanoparticles and ZnNb2O6 generates negatively charged Au which can activate molecular oxygen to form the exclusive high-active peroxide (NbOOAu) species on Au/ZnNb2O6 surface under visible light irradiation, observed in situ by diffuse reflectance infrared Fourier transform spectra (DRIFTS). The optimal NbOOAu species produced on the surface of Au/ZnNb2O6 can remove the H atom of the methylene group (−CH2–) of benzyl alcohol, leading to high photocatalytic activity of Au/ZnNb2O6 compared with Au/NiNb2O6 and Au/CoNb2O6. This modulation of interaction of Au and niobates for the activation of molecular oxygen provides a new prospect for highly selective photocatalytic oxidation reactions.