Tailored hybridization of MIL-101(Cr) with graphene oxide enables enhanced hydrogen storage and delivery

Abstract

The development of practical hydrogen (H₂) storage solutions is essential for a net-zero, secure, and affordable energy future. This study explores the effect of the hybridization method on the H₂ storage and delivery performance of nanoporous MIL-101(Cr)@GO materials, composed of micro–mesoporous Cr terephthalate MIL-101(Cr) and graphene oxide (GO). MIL-101(Cr) was chosen for its high surface area, open metal sites and stability, while GO was selected for its higher density and potential to enhance H₂ storage when combined with MIL-101(Cr). Three hybridization approaches were employed: one in situ method and two ex situ methods, namely post-synthetic modification and physical blending using resonant acoustic mixing (RAM). The impact of these methods on the structural, textural and adsorption properties of the hybrids was systematically analyzed. GO incorporation consistently reduced the surface area of all hybrids but promoted ultramicroporosity (pore width <0.7 nm). Ex situ hybrids retained textural features closer to the pristine MOF and exhibited higher gravimetric H₂ uptake than pure MIL-101(Cr) and the in situ hybrid. Notably, they achieved up to 22% higher excess H₂ uptake (wt%) at 273 K and 100 bar compared to bare MIL-101(Cr). On the other hand, the in situ hybrid, despite a lower gravimetric capacity, demonstrated a threefold increase in tapped density, resulting in a 6–7% improvement in volumetric H₂ performance: total stored and deliverable. These findings highlight the critical role of synthesis strategy in tailoring hybrid material properties to optimize H₂ storage and delivery under varying conditions.