Controllable synthesis of Pd-zeolitic imidazolate framework-porous graphene oxide (Pd-ZIF-pGO) with enhanced catalytic properties for the reduction of nitroarenes

Zeolitic imidazolate framework/graphene oxide (ZIF/GO) composites couple the advantages of ZIFs and GO, and have attracted considerable attention, like in catalysis. But the fabrication of high-performance ZIF/GO composites still faces a huge challenge. Herein, GO was pretreated by base and acid to produce porous GO (pGO), and then Pd-ZIF-pGO composite catalysts were fabricated by coupling pGO, two-dimensional (2D) ZIF-L and PVP-Pd in-situ. The pretreatment of GO significantly affects the surface properties and microstructure of GO, and the corresponding catalytic activity of Pd-ZIF-GO in the hydrogenation of p-nitrophenol. Sequential base-acid treatment can produce porous Pd-ZIF-baGO hybrid with abundant surface defects and suitable surface groups, improving the dispersion and loading of Pd, promoting the mass and electron transfer, thereby enhancing the catalytic performance as compared to Pd-ZIF-GO, with the conversion of 96.4% vs. 76.8% at 30 min. Pd-ZIF-baGO also exhibits better catalytic activity than Pd-ZIF-GO in the hydrogenation of other nitroarenes including o-nitrophenol, m-nitrophenol, and p-nitrotoluene. Furthermore, Pd-ZIF-baGO displays good recyclability in the reduction of p-nitrophenol. The work provides a feasible way to fabricate high-performance ZIF/GO composites.