Subnanometer Ni Clusters on MgH₂: Unveiling Charge Transfer and Hydrogen Mobility Enhancement through ab Initio...

Area of Science:

• Materials Science
• Catalysis
• Computational Chemistry

Background:

• Magnesium hydride (MgH2) is a promising material for solid-state hydrogen storage.
• Its practical application is hindered by high dehydrogenation temperatures and slow kinetics.

Purpose of the Study:

• To investigate the catalytic effect of nickel (Ni) clusters on MgH2 dehydrogenation.
• To understand the mechanism of Ni-catalyzed hydrogen release from MgH2.

Main Methods:

• Ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT).
• Calculations of formation and binding energies for Ni clusters (Ni1-Ni7) on MgH2 surface.
• Analysis of charge transfer, radial distribution function, mean square displacement, density of states, and vibrational properties.

Main Results:

• Small Ni clusters, particularly Ni3 and Ni4, optimize hydrogen binding and structural flexibility.
• The Ni4 cluster significantly enhances hydrogen mobility at elevated temperatures.
• Subnanometer Ni clusters, especially Ni4-2, demonstrate efficient catalytic activity for MgH2 dehydrogenation.

Conclusions:

• Subnanometer Ni clusters, particularly Ni4, effectively catalyze MgH2 dehydrogenation.
• These findings provide insights for designing advanced hydrogen storage materials.