Hybrid Ni–Al layered double hydroxide/graphene composite supported gold nanoparticles for aerobic selective oxidation of benzyl alcohol
In this work, a Ni–Al layered double hydroxide/graphene (NiAl-LDH/RGO) nanocomposite which was synthesized by introducing NiAl-LDH on the surface of graphene oxide (GO) and simultaneously reducing graphene oxide without any additional reducing agents was utilized as the support for Au nanoparticles. Raman spectroscopy and XPS analysis revealed that the NiAl-LDH/RGO composite had both defect sites and oxygenic functional groups in RGO to control the directional growth of Au nanoparticles and lead to a small particle size. Compared to an Au catalyst supported on single GO and RGO or NiAl-LDH, this composite-supported Au catalyst (Au/NiAl-LDH/RGO) exhibited superior catalytic activity and stability in the selective oxidation of benzyl alcohol using molecular oxygen under low pressure. Improved activity was mainly ascribed to the small Au particle size effect caused by RGO and the contribution of basic sites in NiAl-LDH. Moreover, the preferable catalytic stability of the Au/NiAl-LDH/RGO catalyst was attributed to the defect sites and oxygenic functional groups in RGO which anchored the Au NPs and prevented the agglomeration, meanwhile, the agglomeration of RGO was inhibited by the introduction of NiAl-LDH.