Gold nanoparticles supported on modified dumbbell shaped nanorod cluster CuBi2O4 for the selective oxidation of benzyl alcohol under visible light

Abstract

Dumbbell-shaped nanorod cluster CuBi2O4 was fabricated by a hydrothermal method, and a variety of × wt% Au/CuBi2O4 (x = 1, 2, 3, 4, 5, 6) were prepared by NaBH4 reduction method. By using XRD, XPS, SEM, TEM, UV–vis DRS and BET, it was demonstrated that the catalysts were successfully synthesized. Density functional theory (DFT) was used to study the band structure, density of states (DOS) and differential charge density of catalysts. DFT results showed that the energy gap of CBO and Au/CBO was 1.74 eV and 1.59 eV, respectively. Because of Au loading, the recombination of e- and h+ pairs is significantly inhibited because h+ has a greater effective mass in the VB and its photocatalytic selective oxidation of benzyl alcohol is enhanced. Au was found to have an important effect on the enhancement of the photocatalytic activity of the catalyst. Au/CuBi2O4 composites have dramatically a higher degree of separation of the photogenerated carriers than that of pristine CuBi2O4 according to PL and EIS. By optimizing the reaction conditions and comparing different catalysts, GC and GC–MS revealed that 4 wt% Au/CuBi2O4 was the optimum catalyst. Under green mild conditions, the conversion of benzyl alcohol to benzaldehyde can achieve 88.9% with a selectivity of 99%. Moreover, the catalyst was stable by the reuse experiment. A plausible mechanism for the selective oxidation of benzyl alcohol was proposed based on the DFT and experimental results.