In Situ Preparation of Nickel Nanoparticles and Their Effects on the Hydrogen Storage Properties and Oxidation Resistance of Ti–Fe–Mn-Zr Alloy

In this work, nickel nanoparticles were prepared on the surface of the TiFe 0.8 Mn 0.15 Zr 0.05 alloy by electroless deposition. The effects of nickel nanoparticles on hydrogen storage properties and oxidation resistance of the TiFe 0.8 Mn 0.15 Zr 0.05 alloy were systematically investigated. The results showed that the amount and distribution areas of nickel nanoparticles enlarged with the deposition time (0, 10, 15, 20, 30, and 40 min). With the continuous accumulation of nickel nanoparticles, the maximum hydrogen storage capacity decreased slightly from 1.89 wt % (0 min) to 1.80 wt % (40 min). In addition, the hydrogenation reaction rate of all samples presented a trend of increasing first and then decreasing with deposition time. The pristine alloy required approximately 1372 s to achieve 90% capacity during the first hydrogenation. In contrast, the nickel nanoparticle-coated alloys with deposition times of 10 and 20 min demonstrated significantly faster kinetics, requiring only 63.05% and 77.99% of this time, respectively. The phenomenon revealed that nickel nanoparticles enhanced hydrogenation kinetics and the catalytic activity of nickel nanoparticles to hydrogenation kinetics was closely related to distribution and arrangement. At the same time, the deposition of nickel nanoparticles barely changed the thermodynamic properties of the alloy. The enthalpies of hydrogen absorption of pristine alloy (0 min) and nickel nanoparticle-coated alloy (40 min) were −24.817 and −23.478 kJ·mol –1, respectively. More importantly, the oxidation resistance of alloy had a significant improvement after being modified by nickel nanoparticles. Finally, the rate-limiting step of the first hydrogenation of all samples before and after air exposure was studied in detail.