An In-Situ-Grown Cu-BTC Metal−Organic Framework / Graphene Oxide Hybrid Adsorbent for Selective Hydrogen Storage at Ambient Temperature

Abstract

A Cu-BTC metal−organic framework hybrid with graphene oxide (GO) having ultralow GO content (1 wt %) was developed in situ and was explored as a medium for hydrogen storage at ambient temperature. The structural integration of both counterparts in the Cu-BTC/GO hybrid was attained through interaction of the Cu centers with the oxygen-bearing groups of GO by equatorial and axial coordination upon in-situ growth. As a result, Cu-BTC/GO showed enhanced surface area, pore volume, and microporosity, while its hydrogen storage capacity was increased by ∼60%, compared to pure Cu-BTC at 298 K and 1 bar, accompanied by low heat of adsorption (<16.3 kJ mol−1), and 100% recovery of the initial capacity, as tested upon six successive PSA cycles. For hydrogen purification applications, selective hydrogen storage was also investigated and it was found that Cu-BTC/ GO exhibited a 49% and 38.5% higher H2/O2 and H2/N2 selectivity, respectively (10.13 for H2/O2 and 8.64 for H2/N2), at 298 K and 1 bar compared to that of the pure Cu-BTC. The respective selectivity values of the Cu-BTC/GO adsorbent at 100 mbar reached 42.22 and 71.54. Furthermore, the GO incorporation into the hybrid was found to suppress hydrophilicity compared to the pure MOF. This work brings up the potential of in-situ-developed MOF/GO hybrids as multifunctional hydrogen storage media.