Uranium is a key resource for the development of the nuclear industry, and extracting uranium from the natural seawater is one of the most promising ways to address the shortage of uranium resources. Herein, a semiconducting covalent organic framework (named NDA‐TN‐AO) with excellent photocatalytic and photoelectric activities was synthesized. The excellent photocatalytic effect endowed NDA‐TN‐AO with a high anti‐biofouling activity by generating biotoxic reactive oxygen species and promoting photoelectrons to reduce the adsorbed UVI to insoluble UIV, thereby increasing the uranium extraction capacity. Owing to the photoinduced effect, the adsorption capacity of NDA‐TN‐AO to uranium in seawater reaches 6.07 mg g−1, which is 1.33 times of that in dark. The NDA‐TN‐AO with enhanced adsorption capacity is a promising material for extracting uranium from the natural seawater.

The inherent features of covalent organic frameworks (COFs) make them highly attractive for uranium recovery applications. A key aspect yet to be explored is how to improve the selectivity and efficiency of COFs for recovering uranium from seawater. To achieve this goal, a series of robust and hydrophilic benzoxazole‐based COFs is developed (denoted as Tp‐DBD, Bd‐DBD, and Hb‐DBD) as efficient adsorbents for photo‐enhanced targeted uranium recovery. Benefiting from the hydroxyl groups and the formation of benzoxazole rings, the hydrophilic Tp‐DBD shows outstanding stability and chemical reduction properties. Meanwhile, the synergistic effect of the hydroxyl groups and the benzoxazole rings in the π‐conjugated frameworks significantly decrease the optical band gap, and improve the affinity and capacity to uranium recovery. In seawater, the adsorption capacity of uranium is 19.2× that of vanadium, a main interfering metal in uranium extraction.

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Extracting uranium from seawater with a chemically stable adsorbent is one of the most promising strategies for challenges originating from sustainable nuclear energy industries. Covalent organic frameworks (COFs) featuring highly stable and regular porous network structures possess practical advantages compared to other adsorbents such as metal–organic frameworks. We are interested in designing rational monomers to achieve novel COFs and understanding structure–property relationships to improve the performance of natural seawater uranium extraction. In particular, biofouling is a critical issue for long-term uranium extraction in natural seawater, where it would cause a severe decrease in extraction capacity and high costs for adsorbent recycling. On the basis of the fully planar conjugated feature and photoelectric effect of triazine units, we successfully prepared a highly stable two-dimensional COF (named PT-BN-AO) that is based on triazine as central planar units and bridged by an olefin linkage with prominent antibiofouling activity and greatly enhanced uranium extraction capacity. On the basis of the superior photocatalytic performance of PT-BN-AO, it can generate biotoxic reactive oxygen species to sterilize bacteria effectively. Meanwhile, the photoelectric effect of PT-BN-AO promotes the reduction of U­(VI) to U­(IV) by photoelectrons, thus greatly improving the adsorption capacity of uranium. On the basis of the excellent photocatalytic and photoelectric properties, the extraction capacity of PT-BN-AO for uranium in natural seawater reached 5.78 mg g–1, which is 1.42 times that without light irradiation. The excellent performance of PT-BN-AO makes it an advanced material for the practical extraction of uranium from seawater.

Uranium is a key resource for the development of the nuclear industry, and extracting uranium from the natural seawater is one of the most promising ways to address the shortage of uranium resources. Herein, a semiconducting covalent organic framework (named NDA‐TN‐AO) with excellent photocatalytic and photoelectric activities was synthesized. The excellent photocatalytic effect endowed NDA‐TN‐AO with a high anti‐biofouling activity by generating biotoxic reactive oxygen species and promoting photoelectrons to reduce the adsorbed UVI to insoluble UIV, thereby increasing the uranium extraction capacity. Owing to the photoinduced effect, the adsorption capacity of NDA‐TN‐AO to uranium in seawater reaches 6.07 mg g−1, which is 1.33 times of that in dark. The NDA‐TN‐AO with enhanced adsorption capacity is a promising material for extracting uranium from the natural seawater.

Photocatalysis is regarded as one of the most promising technologies to remove organic contaminants. At present, most of the covalent organic frameworks (COFs) used as photocatalysts are connected by imine or borate bonds, which have relatively low stability and relatively poor π-delocalization. Herein, we report, for the first time, vinylene-linked COFs constructed by various diacetylene and triazine moieties for photocatalytic degradation of organic contaminants and disinfection of bacteria. The pioneering introduction of diacetylene moieties not only enhances conjugated π-electrons delocalization but also optimizes the electronic band structures that significantly improve photocatalytic activity. Therefore, the vinylene-bridged COFs have excellent photocatalytic activity with ultrahigh stability and great π-electron delocalization, thus exhibiting ultrafast photocatalytic degradation efficiency for phenol and norfloxacin (>96%, within 15 min). Our work provides a strong basis for the rational regulation of the chemical structure of COFs to enhance their photocatalytic activity, thus broadening the application of COFs in photocatalysis.

Biofouling is a major obstacle to the efficient extraction of uranium from seawater due to the numerous marine microorganisms in the ocean. Herein, we report a novel amidoxime (AO) crystalline covalent organic framework (BD-TN-AO) by Knoevenagel condensation reaction of 2,2′,2″-(benzene-1,3,5triyl)triacetonitrile (TN) and 4,4′-(buta-1,3-diyne-1,4-diyl)dibenzaldehyde (BD) that is highly conjugated and possesses excellent photocatalytic activity. The excellent photocatalytic activity endows the BD-TN-AO high anti-biofouling activity by producing biotoxic reactive oxygen species (ROS) and photogenerated electrons to efficiently reduce the loaded U(VI) to insoluble U(IV). Meanwhile, the surfacepositive electric field has strong electrostatic attraction to the negative [UO 2 (CO 3 ) 3 ] 4− in seawater, which can significantly enhance the extraction capacity of uranium. Benefiting from these outstanding photoinduced effects of BD-TN-AO, the adsorbent exhibits a high uranium adsorption capacity of 5.9 mg g −1 under simulated sunlight irradiation in microorganism-containing natural seawater, which is 1.48 times the adsorption capacity in darkness.

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