Ultrathin 2D Ni‐UMOF Composites for Highly‐Efficient 4‐Nitrophenol Hydrogenation

Abstract

AbstractIt is a challenge to synthesize metal‐organic frameworks (MOFs) catalysts with high catalytic activity and stability under reaction conditions. For this study, the combinations of two‐dimensional (2D) ultrathin nickel‐organic framework (Ni‐UMOF) with layered graphitic carbon nitride (g‐C3N4) or graphene oxide (GO) as promising composite catalysts for the hydrogenation of 4‐nitrophenol were reported. The ultrathin nanosheet composites (Ni‐UMOF/g‐C3N4 and Ni‐UMOF/GO) are obtained by a simple sol‐gel method and exhibit higher hydrogenation activity and recyclability than commercial Pd/C or Pt/C catalysts. The structures and properties of the catalysts are elucidated by X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscope (AFM), fourier transform infrared spectra (FT‐IR), Raman, ultraviolet–visible spectroscopy (UV‐Vis), X‐ray photoelectron spectroscopy (XPS), electron spin‐resonance spectroscopy (ESR) and temperature‐programmed reduction (TPR). The results reveal that oxygen vacancies are produced on the surface of Ni‐UMOF composites and act as the dominating active sites during hydrogenation process. This sol‐gel method can be applied to synthesize other 2D ultrathin MOFs composites with high catalytic activities and recyclability for redox reactions.