Novel hydrogen-bonded organic framework (HOF) for highly efficient photocatalysis: From structural designs to multifunctional applications

Hydrogen-bonded organic frameworks (HOFs), an emerging category of porous crystalline materials, are engineered via intermolecular H-bonding between organic monomers. Distinctive features of HOFs, including ease of solution processing, high crystallinity, and facile regeneration, have sparked significant research interest, providing innovative platforms for diverse multifunctional applications. Here, we summarize the strategies to expand the stability of HOFs, such as strengthening intermolecular interactions (via integrating multiple H-bonds and creating assisted H-bonds), introducing additional intermolecular interactions (including it-it stacking and Van der Waals (VDW) interactions), interpenetration, avoiding donor/acceptor structure formation, and crosslinking. In photocatalysis, visible light absorption is crucial, so to enhance this property of HOFs, several building blocks, including pyrene, perylene, porphyrin, heptazine units, and the addition of metal, are thoroughly discussed. Furthermore, this review explored the creation of heterojunctions, such as conventional heterojunction and Z/S-scheme, as modification strategies, along with their synergistic effects on enhancing the photocatalytic performance of HOF-based materials. With the growing immense potential applications of current HOF-related research in addressing critical environmental and energy challenges, this review emphasizes advancements in dyes and antibiotics degradation, energy conversion processes such as CO2 conversion, H2 and O2 evolution, and reduction of toxic metal-ions, especially U(VI). Lastly, the forthcoming prospects and challenges related to HOFs are explored.