Syntheses, Characterizations And Hydrogen Storages Properties Of Pt@MOFs/GO Composites

In this paper, series of HKUST-1/GO composites with different contents of graphene oxide(GO), and the ZIF-8/GO5composite have been prepared, using GO and two types ofmetal-organic frameworks (MOFs)--HKUST-1(Cu) and ZIF-8(Zn). The Pt@H-GO5andPt@Z-GO5composites were successfully obtained the loading of Pt nanoparticles into MOFs/GOsupports by the methods of ultrasonic impregnation and in-situ reduction. The forming mechanismof such materials were revealed by IR spectroscopy, X-ray powder diffraction (XRD), energydispersive spectrometer (EDS), scanning electron microscopy (SEM), and transmission electronmicroscopy (TEM). The porosities were investigated using the gas adsorption/desorpton analyzer.In zddition, hydrogen capacities and hydrogen storage mechanisms of composites at77K and298K were discussed.(1) Series of HKUST-1/GO composites were synthesized by a simple method of oil bath, thevalue of experimental hydrogen storage of the composite doped with5wt%GO content washigher than the theoretical one.(2) The Pt@H-GO5composite was prepared by doping Pt nanoparticles into H-GO5supportusing the ultrasonic impregnating method, which showed a significant hydrogen spillover effect atambient temperature. The results revealed that the hydrogen storage capacity of such system wasremarkably enhanced by a factor of above2.62and3.83times, compared with HKUST-1andH-GO5at298K, respectively.(3) Pt@Z-GO5composites were synthesized by two methods of ultrasonic impregnation andin-situ reduction. The Pt@Z-GO5composite prepared by in-situ method showed a bettermorphology, and uniform particle size of ZIF-8crystals. In addition, Pt particles arewell-dispersed and have uniform size. The hydrogen storage capacity at ambient temperature ofthe composite was enhanced by a factor of above10.5and12times, compared with ZIF-8andZ-GO5, respectively. This can be ascribed to the presence of hydrogen spillover effect.(4) The ZIF-8, Z-GO5and Pt@Z-GO5composites prepared in methanol solution have asignificant uptake of CO2at293K; the ZIF-8and Z-GO5materials can be used for the selectiveadsorption and separation of H2/CO2.