Rare-Earth Doped Transition Metal–Organic Framework (RE–TM–MOF) for Efficient Photo catalytic Hydrogen Evolution

The core structure of the rare-earth doped transition metal–organic framework (RE–TM–MOF) incorporating Ru-doped Ag within a phenanthroline framework can be described as a multifunctional hybrid system in which each component plays a synergistic role in enhancing photocatalytic hydrogen evolution. At the center of the architecture, a Ru (phen)₃²⁺ complex acts as an efficient photosensitizer, owing to its strong metal-to-ligand charge transfer (MLCT) transitions and excellent visible-light absorption capability. This Ru–phenanthroline unit is either encapsulated within or anchored onto the MOF framework through coordination interactions with the phenanthroline ligands, which serve as π-conjugated organic linkers facilitating electron transport. Surrounding this core, silver (Ag) functions as the primary transition metal node, forming coordination bonds with oxygen or nitrogen donor atoms to construct the MOF network. The presence of Ag not only provides catalytic active sites but also contributes to enhanced charge mobility and plasmonic light absorption effects. Simultaneously, rare-earth ions such as Nd³⁺ or Ce³⁺ are incorporated into the framework as dopants, introducing discrete f-orbital energy levels that act as charge trapping centers, thereby suppressing electron–hole recombination and prolonging charge carrier lifetimes. Structurally, the system can be viewed as a core–shell-like arrangement, where the Ru–phenanthroline complex forms the photoactive core, the Ag-based nodes act as electron mediators, and the RE-doped MOF constitutes the outer porous framework. Upon light irradiation, excited electrons generated in the Ru center are efficiently transferred through the Ag nodes and stabilized by the rare-earth ions before participating in proton reduction to produce hydrogen. This integrated design enables improved light harvesting, efficient charge separation, and accelerated electron transfer, making the RE–TM–MOF system highly effective for photo catalytic hydrogen evolution.