Mechanical Strain Modulates Hydrogen Desorption in Transition-Metal Intercalated Bilayer Graphene

Hydrogen storage remains a key challenge for clean energy technologies, and researchers are continually seeking ways to release stored hydrogen efficiently at everyday temperatures and pressures. Jongdeok Kim from Konkuk University, Vikram Mahamiya from The Abdus Salam International Centre for Theoretical Physics, Massimiliano Di Ventra from the University of California, San Diego, and Hoonkyung Lee from Konkuk University, have now demonstrated a novel method for controlling hydrogen release using mechanical force applied to bilayer graphene containing transition metals. The team’s work reveals that carefully adjusting the distance between graphene layers allows precise control over the interaction between the metal and hydrogen molecules, effectively lowering the temperature required for hydrogen desorption. This approach works by subtly redistributing electrical charge within the material, minimizing the bonding between the metal and hydrogen without changing the overall charge, and represents a significant step towards practical hydrogen storage solutions in layered nanomaterials. The findings build upon recent experimental successes with similar materials, suggesting a viable pathway to overcome the longstanding problem of high desorption temperatures.

Transition-metal functionalized nanomaterials offer promising avenues for hydrogen storage, leveraging their ability to bind multiple hydrogen molecules through a process called Kubas interaction. However, achieving efficient hydrogen release under practical conditions remains a significant hurdle. This research presents a novel approach to control hydrogen desorption temperatures in transition-metal intercalated bilayer graphene by applying external mechanical forces. The method utilizes computational modelling and thermodynamic calculations to demonstrate that adjusting the material’s structure significantly influences how easily hydrogen desorbs.

DFT Modeling of Hydrogen Adsorption on 2D Materials

This research investigates the potential of graphene decorated with transition metals, specifically scandium, titanium, and vanadium, for reversible hydrogen storage. The study employs computational modelling to explore how hydrogen interacts with these materials, focusing on maximizing storage capacity and ensuring efficient release. Key findings reveal that decorating graphene with transition metals significantly enhances hydrogen adsorption compared to pristine graphene, as the metals act as binding sites. Scandium-decorated graphene shows particular promise, exhibiting high adsorption capacity and relatively weak binding energies, suggesting good reversibility.

Controlling the spacing between layers in multi-layered graphene structures is crucial, as adjusting this spacing can enhance hydrogen adsorption and storage capacity. Reversibility is paramount, requiring weak binding energies to ensure hydrogen can be easily released, making the storage process practical. The research compares the performance of different transition metals in terms of their ability to store and release hydrogen. Furthermore, the study extends beyond graphene to explore related two-dimensional materials, assessing their potential for hydrogen storage. This research contributes to the ongoing search for efficient hydrogen storage materials.

The findings suggest that transition-metal decorated graphene and related materials hold promise for achieving high storage capacity and reversibility. The ability to tune interlayer spacing and optimize adsorption sites offers a pathway to further enhance performance, potentially contributing to the development of next-generation hydrogen storage technologies for clean energy, transportation, and other fields. In essence, the paper demonstrates that carefully designed two-dimensional materials with transition metal decorations can provide a viable platform for reversible hydrogen storage, offering a potential solution to a key challenge in developing a hydrogen-based economy.

Layer Spacing Controls Hydrogen Release Strength

Researchers are exploring innovative ways to store hydrogen using materials functionalized with transition metals, aiming to create efficient and practical hydrogen storage systems. Recent work focuses on controlling hydrogen release by manipulating the physical structure of these materials, specifically by adjusting the distance between layers. The team discovered that precisely controlling the interlayer spacing allows them to fine-tune the strength of the interaction between the transition metal and hydrogen molecules. Calculations reveal that complete hydrogen desorption occurs when the interlayer distance is reduced to specific thresholds for different metals, below 4.

7 Å for scandium, 5. 3 Å for titanium, and 5. 1 Å for vanadium. This control arises from a redistribution of charge, minimizing the attraction between the metal and the hydrogen, even though the total charge remains constant. This ability to manipulate hydrogen release through mechanical force represents a significant step towards practical hydrogen storage.

The team employed detailed calculations to predict how many hydrogen molecules would remain bound at different temperatures and pressures, finding that full release occurred at temperatures exceeding 550 K for scandium, 700 K for titanium, and 800 K for vanadium. These temperatures are far above the desired range for practical applications, highlighting the need for a method to lower the desorption temperature. Building on this understanding, the researchers demonstrated that reducing the interlayer spacing effectively lowers the energy required for hydrogen release, potentially overcoming a major obstacle in the development of efficient hydrogen storage materials.

Layer Spacing Controls Hydrogen Adsorption Desorption

This research demonstrates that controlling the spacing between layers in transition metal-intercalated bilayer graphene allows for precise tuning of hydrogen adsorption and desorption. By employing computational modelling, the team showed that reducing the interlayer distance to below specific thresholds, approximately 4. 7 Å for scandium, 5. 3 Å for vanadium, and 5. 1 Å for titanium, leads to complete hydrogen desorption at realistic temperatures and pressures.

This effect arises from a redistribution of charge between the metal atoms, graphene layers, and hydrogen molecules, effectively weakening the binding between the metal and the hydrogen. The findings suggest a viable pathway towards practical hydrogen storage solutions, addressing the long-standing challenge of achieving efficient hydrogen release from functionalized nanomaterials. The ability to modulate hydrogen interaction energies through external mechanical forces offers a promising strategy for reversible hydrogen storage in layered nanostructures.