Synergistic enhancement of hydrogen storage performance of Mg-La-Ni alloy by CeO2@C composite catalyst

Abstract

An enhanced chemical blowing carburation method was successfully employed to synthesize a CeO2@C composite catalyst. The catalyst comprises highly dispersed CeO2 nanoparticles within a porous carbon matrix, demonstrating a well-developed micropore structure, an ultrahigh specific surface area, and a high density of defects. Various amounts of CeO2@C were mechanically milled with an Mg96La3Ni alloy to investigate its hydrogen storage properties. The results demonstrated that incorporating CeO2@C significantly refined the Mg-based alloy, leading to an increase in both specific surface area and the number of active sites. The addition of CeO2@C greatly enhanced the hydrogen absorption and desorption kinetics of the alloy, with the optimal amount being 5 wt % CeO2@C. At 360 °C, the alloy could absorb 78.1% of its maximum hydrogen capacity within 2 min, and release an equal amount of hydrogen within 5 min, with the desorption activation energy decreasing to 107.33 kJ/mol H2. The incorporation of CeO2@C significantly reduced the desorption activation energy of the alloy while leaving its thermodynamic performance unaffected. The CeO2 nanoparticles and carbon matrix synergistically catalyze the reactions, with the former primarily facilitating nucleation and the latter facilitating hydrogen diffusion. This study offers novel insights into the design of magnesium-based hydrogen storage materials. The enhanced hydrogen storage performance demonstrated in this work shows the potential of CeO2@C modified Mg-based alloys for practical applications in hydrogen fuel cell vehicles, portable power sources, and other hydrogen energy storage systems.