Three-dimensional porous materials combining graphene aerogels (GA) and metal-organic frameworks (MOFs) have emerged as promising candidates for hydrogen (H₂) and carbon dioxide (CO₂) storage. These hybrid systems, such as GA-ZIF-8, integrate the high surface area and tunable porosity of MOFs with the mechanical robustness and conductive network of graphene aerogels. The resulting architectures exhibit enhanced gas adsorption capacities, improved structural stability, and superior cycling performance compared to pure MOFs or aerogels.

The design of GA-MOF hybrids begins with the synthesis of a graphene aerogel scaffold, typically through hydrothermal reduction or freeze-drying of graphene oxide dispersions. This process creates a macroporous framework with interconnected channels that facilitate mass transport. MOF crystals, such as ZIF-8, are then grown within the aerogel matrix via solvothermal or in-situ crystallization methods. The MOF nanoparticles anchor onto the graphene sheets, forming a hierarchical pore structure with microporous regions from the MOF and meso/macroporous voids from the aerogel. This multiscale porosity is critical for optimizing gas diffusion kinetics while maintaining high adsorption sites.

Gas storage in GA-MOF hybrids relies on physisorption mechanisms, where H₂ and CO₂ molecules interact with the material through van der Waals forces and electrostatic interactions. The high surface area of MOFs, often exceeding 1000 m²/g, provides abundant adsorption sites, while the graphene aerogel enhances the accessibility of these sites by preventing MOF aggregation. For H₂ storage at cryogenic temperatures (77 K), GA-ZIF-8 hybrids demonstrate capacities ranging from 1.5 to 2.5 wt%, outperforming pure ZIF-8 due to improved pore utilization. At room temperature, the weaker H₂-MOF interactions limit storage to below 1 wt%, but the graphene aerogel’s conductive network may facilitate spillover effects, slightly enhancing uptake.

CO₂ adsorption in GA-MOF hybrids benefits from the polarizable frameworks of MOFs, which interact strongly with CO₂’s quadrupole moment. GA-ZIF-8 exhibits CO₂ capacities of 2–4 mmol/g at 1 bar and 298 K, comparable to pure ZIF-8 but with faster adsorption kinetics due to the aerogel’s open structure. The hybrids also show selectivity for CO₂ over lighter gases like N₂ or CH₄, attributed to the MOF’s pore chemistry and size exclusion effects.

Cycling performance is a key advantage of GA-MOF hybrids over pure MOFs. Repeated adsorption-desorption cycles often degrade MOF crystals due to framework collapse or pore blockage. The graphene aerogel acts as a structural buffer, distributing mechanical stresses and preserving MOF crystallinity. Studies report that GA-ZIF-8 retains over 90% of its initial gas uptake after 100 cycles, whereas pure ZIF-8 may lose 20–30% capacity under similar conditions. The hybrid’s thermal and chemical stability further ensures long-term performance in practical storage systems.

Compared to pure graphene aerogels, GA-MOF hybrids significantly improve gas storage capabilities. Unmodified aerogels lack the microporosity needed for high-density gas adsorption, typically exhibiting H₂ capacities below 1 wt% and CO₂ uptakes under 1 mmol/g. The incorporation of MOFs introduces tailored pore environments that enhance gas affinity and capacity. However, the aerogel component remains essential for preventing MOF particle aggregation and maintaining mechanical integrity during processing and cycling.

In contrast to pure MOF powders or pellets, GA-MOF hybrids offer easier handling and scalability. The aerogel matrix eliminates the need for binders or compression, which can reduce MOF porosity. Additionally, the hybrid’s monolithic form simplifies integration into storage devices, such as pressurized tanks or membrane systems.

Future developments may focus on optimizing the MOF-aerogel interface to maximize synergistic effects. For example, functionalizing graphene surfaces with heteroatoms or ligands could strengthen MOF anchoring and modify pore chemistry for higher gas selectivity. Tuning the aerogel’s macropore size could further enhance diffusion rates without sacrificing adsorption capacity.

In summary, graphene aerogel-MOF hybrids represent a versatile platform for H₂ and CO₂ storage, combining the strengths of both components while mitigating their individual limitations. Their hierarchical porosity, robust cycling performance, and scalable fabrication make them promising materials for advancing gas storage technologies.