TiCX-decorated Mg nanoparticles confined in carbon shell: Preparation and catalytic mechanism for hydrogen storage

To enhance the hydrogen storage properties of Mg/MgH2, we confine TiCX-decorated Mg nanoparticles (NPs) in 2–3 nm carbon shells through a reactive gas evaporation method. By adjusting the evaporation rate of Mg and Ti, the average particle size of Mg-TiCX@C nanocomposite is controlled below 50 nm, and the content of TiCX is adjusted between 4 and 25 wt%. Among these samples, the Mg88(TiC0.6)12@C nanocomposite with high loading percentage of 88% displays the best hydrogen storage performance. It quickly absorbs 5.5 wt% H2 within 25 min at 523 K and desorbs 4.5 wt% H2 within 60 min at 573 K. The hydrogen storage capacity and kinetics remain stable after ten hydrogenation/dehydrogenation cycles at 523/573 K. The enhanced hydrogen storage kinetics of the nanocomposite is attributed to the synergistic effects of the carbon confinement nanostructure and the catalysis of the nonstoichiometric TiCX decorated on Mg NPs. [Display omitted] •Mg-TiCX nanocomposite is confined in a 2–3 nm thick carbon shell.•By adjusting evaporation rate of Mg and Ti, TiCX content ranges from 4 to 25 wt%.•Mg88(TiC0.6)12@C nanocomposite can release 4.5 wt% H2 in 60 min at 573 K.•TiCX offers active sites for hydrogen dissociation and recombination.•Synergetic effects of carbon shell and TiCX contribute to the superior properties.