Metallized porphyrin-based covalent organic frameworks with orbital-hybridized conduction channels for continuous-flow adsorption-photocatalytic uranium extraction from seawater.

Adsorption-photocatalytic uranium extraction from seawater is emerging as a highly attractive route for sustainable nuclear-fuel supply. However, its efficiency is often limited by a kinetic mismatch between uranyl adsorption (mass transport) and photochemical reduction (electron transfer). Herein, we report a family of metallized porphyrin-based covalent organic frameworks (M-Por-COFs-AO, M = Co, Ni, Cu) in which metal-ligand coordination constructs well-defined π-d hybridized conductive channels. These channels are designed to promote coordinated ion diffusion and electron migration, thereby enabling a balanced adsorption-photocatalysis cycle. Among the series, Ni-Por-COF-AO exhibits the most favorable transport characteristics, delivering an ultrahigh affinity (K d = 1.2 × 109 mL g-1), a superior U/V selectivity ratio (S U/V = 62.7), and a high uranium extraction capacity of 516.9 mg g-1 from 20 ppm uranyl solution. Under visible light in a continuous-flow photochemical system, it achieves a uranium extraction capacity of 21.2 mg g-1 from natural seawater within seven days without sacrificial agents. Mechanistic analyses reveal that the hybridization between the transition-metal e-g orbitals and porphyrin π-systems generates delocalized conductive pathways, enabling directional charge migration and selective ion sieving. This work establishes an orbital-hybridized channel engineering paradigm for COFs and demonstrates a materials-to-device integrated strategy that achieves balanced ion-electron transport for efficient and sustainable uranium recovery from seawater.