Advancing hydrogen-bonded organic framework-based composites for integrated catalysis: A review of interface-oriented...

Hydrogen-bonded organic frameworks (HOFs) have rapidly emerged as promising porous crystalline materials with versatile modularity, structural tunability, and facile synthesis under mild conditions. Their unique assembly via reversible hydrogen bonding endows them with high crystallinity alongside solution processability, distinguishing HOFs from traditional covalent-organic frameworks (COFs) and metal-organic frameworks (MOFs). Harnessing these properties, recent advances have driven significant exploration of HOF-based composites across energy conversion and environmental remediation domains. In this review, we systematically survey the design, synthesis, and application of interface-oriented HOF-based composite materials, emphasizing their multifaceted roles in dual energy conversion processes, namely photocatalytic H₂ evolution and CO₂ reduction, while simultaneously facilitating pollutant degradation. We outline the strategies for integrating HOFs with a broad range of functional materials, including semiconductors, metal nanoparticles, sensitizing dyes, polymers, and inorganic oxides, to create hybrid architectures that enhance light absorption, charge separation, and catalytic efficiency. These multifunctional composites enable effective energy conversion and environmental remediation by combining tunable porosity, robust crystallinity, and tailored interfacial interactions. Additionally, we discuss advancements in biohybrid materials where enzyme immobilization within HOF-based matrices facilitates combined adsorption and catalytic degradation of contaminants. This comprehensive account highlights how HOF composites capitalize on complementary physicochemical features of their constituents to address key limitations of standalone materials, advancing the frontier of sustainable catalysis and separation. The review concludes by identifying critical challenges in stability, scalable processing, and mechanistic understanding, proposing future research directions aimed at realizing practical, high-performance HOF hybrid systems for energy and environmental applications.