Highly dispersed Ni nanoparticles decorated TiO2 microspheres for enhancing hydrogen storage properties of magnesium hydride

While magnesium hydride (MgH 2 ) is widely acknowledged as an encouraging solid-state hydrogen storage material , its practical utility is hampered by the elevated operating temperatures and sluggish kinetic characteristics. To address these limitations, a composite catalyst consisting of Ni nanoparticles (NPs) deposited onto TiO 2 microspheres (Ni/TiO 2 -MS) was developed and employed as a catalytic agent to enhance the hydrogen desorption and absorption properties of MgH 2 . Remarkably, the introduction of Ni/TiO 2 -MS resulted in a significant reduction of the initial dehydrogenation temperature of MgH 2 to 181.4 °C, demonstrating a decrease of 78.2 °C compared to ball-milled MgH 2 (BM-MgH 2 ). The optimal BM-MgH 2 -Ni/TiO 2 -MS facilitated the desorption of 6.3 wt % of hydrogen within 5 min at 300 °C, while at 150 °C, its dehydrogenated product could absorb 5.4 wt % of hydrogen in only 1 minute. Moreover, the BM-MgH 2 -Ni/TiO 2 -MS sample exhibited remarkable cycling stability over 20 cycles. Through the mechanistic analysis, the simultaneous presence of in-situ formation of Mg 2 Ni/Mg 2 NiH 4 and multivalent titanium species engendered a synergistically catalytic effect, significantly enhancing the hydrogen storage capabilities of MgH 2 . This study affords a very potential strategy for the design of active catalysts aimed at enhancing the hydrogen dehydrogenation/absorption kinetics of MgH 2 .