Lithium-Ion-Induced Enhanced Hydrogen Uptake over MIL-101(Cr) Metal-Organic Frameworks

Abstract

A robust and straightforward strategy is demonstrated to improve MIL-101(Cr) hydrogen uptake performance through systematic Li+ ion doping. Several spectroanalytical techniques are employed to investigate the physical, chemical, morphological, and pore textural properties of the synthesized Li-doped MIL-101(Cr) and to establish the incorporation of Li+ ions in Li-MIL-101(Cr) frameworks. Notably, it is observed that the pore textural characteristics of Li-doped MIL-101(Cr) can be fine tuned by varying Li+ ions loading. The hydrogen uptake capacity of 2.74 wt% at 77 K and 1 bar is achieved with Li-doped MIL-101(Cr), which is almost double as compared to the pristine MIL-101(Cr). The experimental findings demonstrate the significance of Li+ ions doping content on the hydrogen uptake performance of Li-doped MIL-101(Cr). The observed remarkable improvement in the H<inf>2</inf> uptake capacity of Li-doped MIL-101(Cr) can be attributed to the enhanced interaction between the doped Li+ ions in the frameworks and H<inf>2</inf> gas. Furthermore, hydrogen adsorption isotherms data of these frameworks are best fitted with three-parameter nonlinear adsorption equilibrium isotherm equations (R2 ≥ 0.999), indicating the nonuniform multilayer adsorption behavior due to the heterogeneous surface of Li-doped MIL-101(Cr). © 2025 Elsevier B.V., All rights reserved.