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

While magnesium hydride (MgH2) 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 TiO2 microspheres (Ni/TiO2-MS) was developed and employed as a catalytic agent to enhance the hydrogen desorption and absorption properties of MgH2. Remarkably, the introduction of Ni/TiO2-MS resulted in a significant reduction of the initial dehydrogenation temperature of MgH2 to 181.4 °C, demonstrating a decrease of 78.2 °C compared to ball-milled MgH2 (BM-MgH2). The optimal BM-MgH2-Ni/TiO2-MS facilitated the desorption of 6.3wt% of hydrogen within 5minutes at 300 °C, while at 150 °C, its dehydrogenated product could absorb 5.4wt% of hydrogen in only 1minute. Moreover, the BM-MgH2-Ni/TiO2-MS sample exhibited remarkable cycling stability over 20 cycles. Through the mechanistic analysis, the simultaneous presence of in-situ formation of Mg2Ni/Mg2NiH4 and multivalent titanium species engendered a synergistically catalytic effect, significantly enhancing the hydrogen storage capabilities of MgH2. This study affords a very potential strategy for the design of active catalysts aimed at enhancing the hydrogen dehydrogenation/absorption kinetics of MgH2.