Preparation of Ni/Ti₃O₅@graphene oxide double heterojunction for enhancing hydrogen storage in MgH₂

Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential. However, its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics. In this study, we prepared a Ni/Ti₃O₅@graphene oxide (GO) dual-heterojunction composite material via solvent heating, electrostatic adsorption, and calcination to improve the hydrogen storage capabilities of MgH₂. Adding Ni/Ti₃O₅@GO to MgH₂ lowered the initial dehydrogenation temperature of MgH₂ to 183 ℃; at a dehydrogenation temperature of 275 ℃, 6.4 wt.% of H₂ escaped from the MgH₂ bulk. In addition, the hydrogen storage material absorbed 1.8 wt.% H₂ at 30 ℃ for 30 min. The calculated activation energy of dehydrogenation was 48.221 ± 0.141 kJ·mol⁻¹, which was significantly lower than that of the ball-milled MgH₂ (112.63 ± 1.44 kJ·mol⁻¹). Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes, resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH₂. In this work, we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.