Improved room-temperature hydrogen storage performance of lithium-doped MIL-100(Fe)/graphene oxide (GO) composite

Li + doping is regarded as an effective strategy to enhance the room-temperature hydrogen storage of metal-organic frameworks (MOFs). In this work, Li + is doped into both MIL-100(Fe) and MIL-100(Fe)/graphene oxide (GO) composite, and it is demonstrated that the hydrogen uptake of Li + doped MIL-100(Fe)/GO (2.02 wt%) is improved by 135% compared with Li + doped MIL-100(Fe) (0.86 wt%) at 298 K and 50 bar, which is ascribed to its higher isosteric heat of adsorption (7.33 kJ/mol) resulting from its more accessible adsorption sites provided by doped Li + ions and ultramicropores. Grand canonical Monte Carlo (GCMC) simulation reveals that Li + ions distributing in the interface between MIL-100(Fe) and GO within MIL-100(Fe)/GO composite is favorable for hydrogen adsorption owing to the increased number of adsorption sites, thus contributing to the enhanced hydrogen storage capacity. These findings demonstrate that MIL-100(Fe)/GO is a more promising Li + doping substrate than MIL-100(Fe).