H-Spillover through the Catalyst Saturation: An Ab Initio Thermodynamics Study

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Hydrogen spillover, the transfer of hydrogen from a catalyst to a receptor, is a promising mechanism for hydrogen storage.
• A key challenge is understanding how hydrogen atoms bind to graphene, avoiding the formation of molecular hydrogen (H2).

Purpose of the Study:

• To elucidate the mechanism of hydrogen spillover onto graphene using computational methods.
• To identify conditions that favor hydrogen adsorption on graphene for efficient hydrogen storage.

Main Methods:

• Ab initio calculations were employed to simulate hydrogen-metal catalyst interactions and hydrogen adsorption on graphene.
• The study investigated the role of catalyst saturation and graphene hydrogenation on the spillover process.

Main Results:

• Catalyst saturation increases the hydrogen chemical potential, creating favorable conditions for spillover.
• While spillover is unfavorable on pristine graphene, hydrogenated graphene significantly enhances C-H binding, facilitating adsorption.
• A low energy barrier (0.7 eV) for hydrogen transfer to hydrogenated graphene was computed, achievable at operational temperatures.

Conclusions:

• Catalyst saturation and pre-hydrogenated graphene are crucial for efficient hydrogen spillover and storage.
• The findings provide a pathway for designing materials and conditions for effective hydrogen storage via the spillover mechanism.