Microwave-assisted synthesis of 2D Zr-MOF nanosheets supported gold nanocomposites as efficient catalysts for the reduction of 4-nitrophenol

Two-dimensional metal-organic framework nanosheets (2D MONs) are excellent heterogeneous catalysts owing to their high density and accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. Moreover, the employment of 2D MONs as supports to encapsulate noble na-noparticles can not only stabilize the noble nanoparticles, but also significantly improve their catalytic activity through the synergetic effect between 2D MONs and noble nanoparticles. Herein, we reported a microwave-assisted method for the rapid preparation of 2D UiO-67 metal-organic framework nanosheets (named UiO-67 NS). The Au nanoparticles modified UiO-67 nanocomposites (denoted as Au/UiO-67 NS nanocomposites) are formed by the in situ reduction of HAuCl4 in the pores of UiO-67 NS. The Au/UiO-67 NS nanocomposites show excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol, and only 20 equivalent sodium borohydride can completely reduce 10 mM 4-NP in 100 s, thanks to highly exposed Au NPs and reduced diffusion distance. In addition, XPS characterizations showed that the binding energy of Au 4 f in Au/UiO-67 NS nanocomposites displays a 0.48 eV less than that of Au nanoparticles on UiO-67 octahedral microcrystals (denoted as Au@UiO-67 OM), which is believed to be responsible for the enhanced catalytic activity toward the reduction of 4-nitrophenol. (C) 2022 Published by Elsevier B.V.