Hydrogen storage on metal oxide model clusters using density-functional methods and reliable van der Waals...

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Developing efficient hydrogen storage materials is crucial for a sustainable energy future.
• Low-coordinated sites on small clusters present unique electronic properties for chemical interactions.
• Understanding hydrogen physisorption mechanisms is key to designing effective storage solutions.

Purpose of the Study:

• To investigate the potential of low-coordinated sites on small model clusters for hydrogen storage.
• To screen various (XY)6 clusters, focusing on hexagonal oxide clusters with a coordination number of three.
• To evaluate the accuracy of different van der Waals (vdW) corrections in density-functional calculations for hydrogen physisorption.

Main Methods:

• Screening of (XY)6 clusters with X = Mg, Ba, Be, Zn, Cd, Na, Li, B and Y = O, Se, S, F, I, N.
• Density-functional calculations employing various vdW corrections.
• Comparison of calculated H2 physisorption profiles with high-accuracy CCSD(T) data.
• Analysis of energy profiles and kinetic constants for H2 splitting.

Main Results:

• Oxide clusters, particularly (MgO)6, (BaO)6, and (BeO)6, emerged as highly promising for hydrogen storage.
• The Grimme D3 vdW correction with the Perdew-Burke-Ernzerhof functional accurately predicted H2 physisorption energies.
• Adsorption energies (0.15–0.21 eV) meet criteria for H2 storage, with likely molecular adsorption and rapid uptake/release kinetics.
• Light elements like Be and Mg contribute to favorable gravimetric storage capacity.

Conclusions:

• Low-coordinated sites on light metal oxide clusters are effective active centers for hydrogen storage.
• Computational methods, specifically DFT with Grimme D3 vdW correction, are suitable for studying these systems.
• The identified clusters offer a promising pathway towards practical hydrogen storage solutions meeting gravimetric requirements.