Lithium-grafted Si-doped γ-graphyne as a reversible hydrogen storage host material

Area of Science:

• Materials Science
• Energy Storage
• Computational Chemistry

Background:

• Hydrogen (H₂) is a promising clean energy carrier, but efficient and safe storage remains a challenge.
• Developing advanced materials is crucial for practical hydrogen fuel implementation.
• Graphene-based materials offer unique properties for energy applications.

Purpose of the Study:

• To investigate Li-grafted Si-doped γ-graphyne (SiG) as a novel material for hydrogen storage.
• To evaluate the binding strength, stability, and storage capacity of the functionalized material.
• To determine the reversibility and desorption characteristics of stored hydrogen.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to study the electronic and structural properties.
• Ab initio molecular dynamics (AIMD) simulations were performed to assess thermal stability at 400 K.
• Hydrogen adsorption/desorption behavior was analyzed using occupancy calculations and AIMD.

Main Results:

• Li functionalization significantly enhanced hydrogen binding strength on SiG by threefold.
• The Li₈SiG system exhibited a binding energy of -2.73 eV, preventing Li clustering.
• A maximum gravimetric capacity of 8.48 wt% was achieved, aligning with US-DOE targets.
• Reversible hydrogen storage was confirmed, with desorption starting at 280 K and completing at 400 K.

Conclusions:

• Li-functionalized Si-doped γ-graphyne is a promising candidate for efficient and reversible hydrogen storage.
• The material's stability and performance metrics meet key requirements for practical hydrogen energy applications.
• The study highlights the potential of tailored nanostructured materials for next-generation energy solutions.