Exploring Hydrogen Storage Efficiency in MgH₂ Using Charred Nanomaterials: A Computational Analysis Integrating DFT and Machine Learning Approaches

Hydrogen, as a clean energy carrier, holds significant potential for reducing CO₂ emissions and diversifying the energy mix (1-3). However, the practical implementation of solid-state hydrogen storage, particularly in hybrid energy systems (HES), faces challenges related to kinetics, stability, and safety (4). This study performs a computational exploration of magnesium hydride (MgH₂) integrated with char nanomaterials, aiming to enhance the efficiency of hydrogen storage systems. We investigate the use of charred nanomaterials as a novel approach to address the fire risk and safety concerns associated with MgH₂, as well as to improve its hydrogen desorption kinetics. We hypothesize that charred nanomaterials can act as dual-function agents, catalyzing hydrogen release while also offering protection against combustion.<br/> <br/>To test our hypothesis, we employ Density Functional Theory (DFT)-based simulations complemented with machine learning techniques. Our study models include various configurations of MgH₂ clusters in contact with charred carbon fragments doped with heteroatoms like Oxygen, Nitrogen, and Iron, alongside O₂ molecule environments to simulate combustion processes. These models are analyzed to understand the stability and interaction dynamics under varying conditions. Our findings reveal that charred nanomaterials significantly influence the hydrogen desorption properties of MgH₂, indicating a promising pathway towards safer and more efficient hydrogen storage. The charred structures, particularly when doped with heteroatoms, not only catalyze hydrogen release but also mitigate risks associated with MgH₂'s reactivity, offering a holistic solution to the current limitations in hydrogen storage technology.<br/> <br/>This computational study provides crucial insights into the design of advanced materials for hydrogen storage, offering a sustainable solution to energy storage challenges in HES. It opens up avenues for further experimental validation and development of MgH₂-based hydrogen storage systems, contributing to the advancement of clean energy technologies.<br/> <br/>References<br/>L. Schlapbach, A. Züttel, Hydrogen-storage materials for mobile applications, Nature, 414 (2001) 353-358.<br/>M. Carmo, D.L. Fritz, J. Mergel, D. Stolten, A comprehensive review on PEM water electrolysis, International Journal of Hydrogen Energy, 38 (2013) 4901-4934.<br/>Y. Cheng, R. Zheng, Z. Liu, Z. Xie, Hydrogen-based industry: a prospective transition pathway toward a low-carbon future, National Science Review, 10 (2023).<br/>G. Glenk, S. Reichelstein, Economics of converting renewable power to hydrogen, Nature Energy, 4 (2019) 216-222.