MOFs as a partner for H2 industry

Abstract

Metal-organic frameworks (MOFs) are hybrid organic-inorganic porous materials composed of transition metal cations and polydentate organic ligands, forming modular architectures with high porosity and surface areas. These properties make MOFs promising candidates for hydrogen (H2) storage and production, catalysis, sensing and gas separation, in between others. Since their conceptualization in 1995 by Omar Yaghi, MOFs have evolved significantly, with over 100,000 types reported, exhibiting surface areas ranging from 500 to 8000 m²/g. Their structural versatility, governed by secondary building units (SBUs) and ligand geometries, allows for tailored pore sizes and functionalities, critical for optimizing H2 storage. MOFs with open metal sites (OMS) enhance H2 adsorption by providing stronger binding sites, while advancements in synthesis methods, such as solvothermal, microwave, and spray drying, have improved scalability and efficiency. Recent developments include MOF composites and bimetallic frameworks, which exhibit synergistic effects for enhanced H2 storage and catalytic performance. For instance, NU-1501 achieves a H2 gravimetric capacity of 14 wt%, while bimetallic MOFs like Zr/Hf-UiO-66 demonstrate superior catalytic activity. Additionally, MOFs are being explored for H2 production via electrocatalysis and photocatalysis, leveraging their tunable electronic properties and high surface areas. Despite challenges in scalability and stability, startups like H2MOF and Rux Energy are pioneering MOF-based H2 storage solutions, aiming to meet U.S. Department of Energy targets for on-board H2 storage. Computational modeling and reticular chemistry further accelerate the design of MOFs with optimized H2 storage capacities, paving the way for their integration into sustainable energy systems. While commercial applications remain limited, ongoing research and industrial collaborations continue to advance MOFs toward practical H2 storage and energy conversion technologies.