In situ High-Energy Synchrotron X-ray Studies in Thermodynamics of Mg-In-Ti Hydrogen Storage System

Achieving dual regulation of the kinetics and thermodynamics of MgH_(2) is essential for the practical applications.In this study,a novel nanocomposite(In@Ti-MX)architected from single-/few-layered Ti_(3)C_(2) MXenes and ultradispersed indium nanoparticles was prepared by a bottom-up self-assembly strategy and introduced into MgH_(2) to solve the above-mentioned problems.The MgH_(2)+In@Ti-MX composites demonstrate excellent hydrogen storage performance:The resultant In@Ti-MX demonstrated a positive effect on the hydrogen storage performance of MgH_(2)/Mg:the dehydrogenated rate of MgH_(2)+15 wt%In@Ti-MX reached the maximum at 330°C,which was 47°C lower than that of commercial MgH_(2);The hydrogenation enthalpy of the dehydrided MgH_(2)+15 wt%In@Ti-MX and MgH_(2)+25 wt%In@Ti-MX were determined to be−66.2±1.1 and−61.7±1.4 kJ·mol^(−1) H_(2).In situ high-energy synchrotron x-ray diffraction technique together with other microstructure analyses revealed that synergistic effects from Ti_(3)C_(2) MXenes and In nanoparticles(NPs)contributed to the improved kinetics and thermodynamics of MgH_(2)(Mg):Ti/TiH_(2) derived from Ti_(3)C_(2) MXenes accelerated the dissociation and recombination of hydrogen molecule/atoms,while In NPs reduced the thermodynamic stability of MgH_(2) by forming the Mg-In solution.Such a strategy of using dual-active hybrid structures to modify MgH_(2)/Mg provides a new insight for tuning both the hydrogen storage kinetics and thermodynamics of Mg-based hydrides.