Enhancing hydrogen storage properties of MgH2 via reaction-induced construction of Ti/Co/Mn-based multiphase catalytic system

[Display omitted] •Synthesized TiO2@MnCo2O4.5 catalyst to improve MgH2 hydrogen storage performance.•Reaction-induced TiO2@MnCo2O4.5 decomposition creates a multiphase, multi-site catalyst environment.•TiO2@MnCo2O4.5 exhibits a synergistic effect in improving hydrogen dissociation and diffusion. The inherent kinetic limitations and high operating temperatures of magnesium hydride (MgH2) hinder its practical applications. Herein, we report the successful synthesis of a TiO2@MnCo2O4.5 composite transition metal oxide catalyst and investigate its effect on the hydrogen storage performance of MgH2. TiO2@MnCo2O4.5 exhibits exceptional catalytic activity in the hydrogen dissociation and recombination reactions of during absorption and desorption processes, reducing the dehydrogenation activation energy of MgH2 to 75.54 kJ/mol. Notably, the MgH2-6 wt% TiO2@MnCo2O4.5 system releases 6.04 wt% H2 within 30 min at 250 °C, and 4.98 wt% H2 within 120 min at 225 °C. Furthermore, it can absorb 5.08 wt% H2 within 3 min at 150 °C and achieve a hydrogen absorption capacity of 2.02 wt% within 30 min even at 30 °C. The reaction-induced decomposition and phase transformation of TiO2@MnCo2O4.5 create a multiphase, multi-site catalytic environment. The hydrogen storage system based on the coexistence of Mg6MnO8, Mn, Ti2O3, and CoO features abundant diffusion pathways and nucleation sites, playing a critical role in suppressing the energy barriers for MgH2 hydrogen absorption and desorption reactions. These findings provide a meaningful theoretical foundation for the microstructural optimization and performance regulation of Mg-based hydrogen storage materials.