High-capacity room-temperature hydrogen storage of zeolitic imidazolate framework/graphene oxide promoted by platinum metal catalyst

Abstract

Pt nanoparticles (NPs) have been immobilized on the support of nanoscale zeolitic imidazolate framework (ZIF-8) and graphene oxide (GO) via a facile liquid impregnation method, in which H2PtCl6, NaBH4 and polyvinyl alcohol (PVA) act as the Pt precursor, reducing and stabilizing agents, respectively. The resulting Pt@ZIF-8/GO composite was characterized by powder X-ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy, energy dispersive spectroscopy and N2 adsorption-desorption analysis. The results showed that Pt metal catalysts with an average size of 3.8 nm were highly dispersed and anchored tightly on the external surface of the ZIF-8/GO support. The hydrogen storage performance of Pt@ZIF-8/GO was investigated. The hydrogen storage capacity of Pt@ZIF-8/GO at 298 K and 10.0 bar is 2.2 times higher than that of the parent ZIF-8. The enhanced hydrogen storage capacity is mainly attributed to the hydrogen spillover mechanism involved in such catalytic systems. The high dispersion and small size of Pt NPs, as well as intimate contacts between the Pt dissociation source and ZIF-8/GO receptor are crucial to achieving such an obvious increase in room-temperature hydrogen storage capacity.