Mechanistically guided design of UiO-66 composites for photocatalytic degradation of dyes: Linking dye chemistry, interfacial interactions, and degradation mechanism

Metal-organic frameworks (MOFs) have attracted significant interest owing to their versatility in addressing water pollution. Among them, UiO-66 has been recognized for its high surface area, tunable porosity, functionalization, structural flexibility, and chemical stability owing to its unique zirconium-terephthalate framework. UiO-66 has emerged as a robust photocatalyst for dye-polluted wastewater; however, the mechanistic understanding of how dye chemistry dictates its degradation pathway remains underexplored. This review evaluates UiO-66-based composites by bridging adsorption, bond-breaking chemistry, and electron-transfer dynamics with the inherent molecular features of cationic and anionic dye degradation. Instead of simply summarizing the structural changes, this review discusses how UiO-66 incorporated with various components, including metal oxides, silver plasmonic systems, COF hybrids, and membrane-supported architectures, plays an active role in initiating dye–catalyst interactions. These interactions are through π–π stacking, electrostatic attraction, dipole coupling, and surface functional groups, which initiate advanced pathways that synergistically promote electron–hole separation and radical generation. Across these systems, this review critically evaluates limitations, including photostability loss, metal leaching, recombination issues, pH instability, interface mismatch, and scalability constraints, which are often overlooked yet essential for practical deployment. This review offers a clear rationale for why some UiO-66 composites perform better by linking material composition to dye-specific mechanistic pathways. This work provides mechanistic, forward-looking design principles for next-generation photocatalysts from a critical, comparative perspective, with a focus on modular architectures, stabilized redox interfaces, and substrate-integrated platforms that bridge laboratory performance to scalable, real-world water purification applications.