Abstract: The nanocomposites were prepared by ball-milling Mg2Ni0.75Cr0.25 alloy fabricated with different mass fractions (0.5%, 1.5%, 2.5%) of TiO2 nanoparticles. The XRD patterns indicate that the nanocomposites contain Mg2Ni-Ni alloys and TiO2 nanoparticles, and the average crystalline sizes are 24~35nm. The TiO2 nanoparticles can act as catalyst and the nanocomposites show rapid absorption and desorption kinetics, and the absorption and desorption temperatures are greatly decreased. The value of absorption enthalpy for hydride formation of the nanocomposite is decreased as compared with nanocrystalline Mg2Ni0.75Cr0.25 alloy. The absorption of the nanocomposite containing 1.5% TiO2 nanoparticles is almost finished within 5min at 373K under the hydrogen pressure of 4MPa, and desorption is almost finished within 20min at 463K under the hydrogen pressure of 0.1MPa. The nanocomposite gives the hydrogen content of 2.57% under the condition.
Improvement in hydrogen absorption and desorption kinetics of Mg2Ni0.75Cr0.25 alloy by addition of TiO2 nanoparticles
Abstract:
The nanocomposites were prepared by ball-milling Mg2Ni0.75Cr0.25 alloy fabricated with different mass fractions (0.5%, 1.5%, 2.5%) of TiO2 nanoparticles. The XRD patterns indicate that the nanocomposites contain Mg2Ni-Ni alloys and TiO2 nanoparticles, and the average crystalline sizes are 24~35nm. The TiO2 nanoparticles can act as catalyst and the nanocomposites show rapid absorption and desorption kinetics, and the absorption and desorption temperatures are greatly decreased. The value of absorption enthalpy for hydride formation of the nanocomposite is decreased as compared with nanocrystalline Mg2Ni0.75Cr0.25 alloy. The absorption of the nanocomposite containing 1.5% TiO2 nanoparticles is almost finished within 5min at 373K under the hydrogen pressure of 4MPa, and desorption is almost finished within 20min at 463K under the hydrogen pressure of 0.1MPa. The nanocomposite gives the hydrogen content of 2.57% under the condition.