Hydrogen storage in incompletely etched multilayer Ti₂CT_x at room temperature

Hydrogen storage materials are the key to hydrogen energy utilization. However, current materials can hardly meet the storage capacity and/or operability requirements of practical applications. Here we report an advancement in hydrogen storage performance and related mechanism based on a hydrofluoric acid incompletely etched MXene, namely, a multilayered Ti₂CT_x (T is a functional group) stack that shows an unprecedented hydrogen uptake of 8.8 wt% at room temperature and 60 bar H₂. Even under completely ambient conditions (25 °C, 1 bar air), Ti₂CT_x is still able to retain ~4 wt% hydrogen. The hydrogen storage is stable and reversible in the material, and the hydrogen release is controllable by pressure and temperature below 95 °C. The storage mechanism is deduced to be a nanopump-effect-assisted weak chemisorption in the sub-nanoscale interlayer space of the material. Such a storage approach provides a promising strategy for designing practical hydrogen storage materials.