Effect of TiS2 on Hydrogen Absorption and Desorption Performance of Mechanically Ball-Milled Mg95Ce5 Alloy

Magnesium-based materials have been considered to be potential hydrogen storage materials due to their high hydrogen storage capacity and abundance in natural resources. In order to improve the hydrogen storage performance of magnesium-based materials, a Mg95Ce5 alloy was prepared by using the vacuum induction melting method. Moreover, TiS2 was used as a catalyst, and a series of Mg95Ce5 + x wt% TiS2 (x = 0, 3, 5 and 10) composites with different TiS2 contents were prepared by the mechanical ball-milling method. The addition of TiS2 as a catalyst broke the inherent symmetry of the Mg95Ce5 alloy at both the atomic and defect levels, potentially improving hydrogen storage by modifying hydrogen diffusion pathways and interaction sites. The structural analysis results indicate that the Mg95Ce5 alloy is composed of Mg and CeMg12 phases. After the hydrogenation process, the Mg and CeMg12 phases in the Mg95Ce5–TiS2 composites transformed into CeH2.73 and MgH2. In addition, CeS2 and TiH1.5 could be detected in the hydrogenated samples, indicating that the TiS2 decomposed and changed into CeS2 and TiH1.5 during the hydrogenation reaction. Adding TiS2 to Mg95Ce5 alloy could significantly improve the hydrogen absorption and desorption kinetic properties, and the dehydrogenation peak temperature of the composites was reduced from 389.5 °C to 329.7 °C when the TiS2 content increased from 0 to 10 wt%. However, the addition of TiS2 inevitably reduced the reversable hydrogen storage capacity of the composites. The hydrogen absorption and desorption thermodynamic measurement results indicate that the TiS2 catalyst has almost no influence on the enthalpy and entropy changes of the composites during the hydrogenation process.