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Although the catalytic activity is heavily reliant on the electronic structure of the catalyst, understanding the impact of electron spin regulation on electrocatalytic performance is still rarely investigated. This work presents a novel approach involving the single‐atom coordination of cobalt (Co) within metalloporphyrin‐based three‐dimensional covalent organic frameworks (3D‐COFs) to facilitate the catalytic conversion for sodium‐iodine batteries. The spin state of Co is modulated by altering the oxidation state of the porphyrin‐centered Co, achieving optimal catalysis for iodine reduction. Experimental results demonstrate that CoII and CoIII are incorporated into the 3D‐COFs, exhibiting spin ground states of S=1/2 and S=0, respectively. The low spin state of CoIII is favorable to hybridize with the sp 3d orbitals of I3−, thus facilitating the conversion of I3− to I−. Density‐functional theory (DFT) calculations further reveal that the presence of CoIII enhances iodide adsorption and accelerates the formation of NaI in 3D‐COFs‐CoIII, thereby promoting its rapid kinetic behaviors. Notably, the I2@3D‐COFs‐CoIII cathode achieves a high reversible capacity of 227.7 mAh g−1 after 200 cycles at 0.5 C and demonstrates exceptional cyclic stability, exceeding 2000 cycles at 10 C with a minor capacity fading rate of less than one 0.01 % per cycle. [ABSTRACT FROM AUTHOR]

With the continuous development of economy and industry, the demand for energy in modern society is ever-increasing. As a kind of high efficiency and low carbon energy, nuclear energy has attracted more and more attention. Developing nuclear energy, however, also brings some problems such as the release of radioactive metal ions that pose a threat to the environment and human health. Therefore, separation and removal of radioactive ions(e.g., U(Ⅵ)) from wastewater is of great significance to ensure the sustainable development of nuclear energy. Covalent organic frameworks(COFs) are a kind of periodic porous polymer materials composed of organic molecular units connected by covalent bonds. The emergence of COFs marks a new era in the field of materials. Because of the design ability of COFs and its unique advantages in structure and pore, it shows a good application prospect in catalysis, sensing and adsorption. Very recent efforts by some investigators have focused on the application of COFs in adsorption and separation of radionuclides, generally with encouraging results. According to the classification from the structural dimension, COFs can be divided into two-dimensional COFs materials(2D-COFs) and three-dimensional COFs materials(3D-COFs). Up to now, 2D COFs materials have been widely studied and applied. In contrast, the development of 3D-COF has been relatively slow, and the performance and application have been limited, a result of the limitations of molecular structural units and topological connections, as well as the difficulties of synthesis and structural analysis. To this end, in this paper, a combination of bond transformation and post-grafting was used to construct functional 3D-COFs materials for the efficient removal of U(Ⅵ) from wastewater. Firstly, the imine bond was reduced to an irreversible amine bond by reduction reaction, and then sulfonic acid group was introduced into the skeleton by reaction with 1, 3-propyl sulfonolactone to successfully synthesize COF-320-H2SO3. The structure and properties of COF-320-H2SO3 were characterized by various characterization methods, and the adsorption behavior of COF-320-H2SO3 on U(Ⅵ) was systematically studied. The results show that the chemical stability of COFs is significantly improved by the conversion of imine bond to amine bond, and the adsorption capacity of the material for U(Ⅵ) is clearly enhanced by the introduction of sulfonic acid group with hydrophilic and strong coordination ability. Even under the conditions of 3 mol/L HNO3, the adsorption capacity of U(Ⅵ) can reach more than 40 mg/g. This work further reveals the potential application value of COFs, especially 3D-COFs materials, in the separation of radioactive metal ions.

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• New [OH] x -BD-TFPM 3D-COFs with pore surface engineering was proposed. • Content-tunable OH groups on channel walls significantly promoted OA capture. • Hydrophobic and hydrophilic multiple groups realized high adsorption performance. • LOD of 0.005 μg/kg was exhibited for OA detection using 3D-COF coupled with LC-MS. • Accurate analysis of OA in shellfish was achieved with good recovery yields. A novel three-dimensional covalent organic framework (3D-COF) with content-tunable and active hydroxyl groups (OH) on the pore walls was developed and adopted for the high-performance capture of okadaic acid (OA) marine toxins. Using pore-surface engineering, the integration of linear building blocks (4,4′-diamino-3,3′-biphenyldiol, BD(OH) 2 and benzidine, BD) with the 3D structural building block backbone (4,4′,4′',4′''-methane-tetrayltetrabenzaldehyde, TFPM) was achieved. By adjusting the ratio of BD(OH) 2 , functional multicomponent-COFs [OH] x -BD-TFPM COFs (X = 25%) were synthesized, which offered ideal access to convert a conventional COF into a functional platform with multiple-mode interactions of hydrophobic and hydrophilic groups for OA capture. [OH] x -BD-TFPM was characterized using SEM, XRD, FT-IR, and BET. The adsorption features and analytical performance of OA were screened and evaluated. Optimization of dispersive solid-phase extraction using [OH] 25 -BD-TFPM was accomplished, and the method was verified for sensitive quantitative detection of OA in clam and mussel samples. Coupled with LC-MS/MS, the resultant [OH] 25 -BD-TFPM COF demonstrated the ability to analyze OA, and the limit of detection for OA in shellfish was determined to be 0.005 μg/kg. A significant improvement in trace OA detection was observed compared to previously reported SPE materials without adjustable hydrophilic interactions. The recoveries of OA in the fortified clam and mussel samples were in the ranges of 93.9‒105.1% and 96.7‒110.2%, respectively. This study highlights that OH-group surface engineering in channel walls is a facile and powerful strategy for developing functional 3D-COFs with multiple interactions for high-performance target capture. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-dimensional COFs was first introduced into the field of Th (IV) separation. • The adsorption capacity of COF-DL229 is higher than reported two-dimensional COF. • COF-DL229 exhibits excellent selectivity for Th (IV) compared to other materials. • The interaction mechanism was explored by characterizations and DFT calculations. A novel porous material tailored for Th (IV) entrapment with not only large capacity but also high selectivity is highly desired for the thorium fuel cycle. Here, a three-dimensional COF (covalent organic framework) material, named COF-DL229 was prepared for the efficiently selective entrapment of Th (IV). Batch sorption experiments indicated that the entrapment of Th (IV) was a pH-dependent, rapid (equilibrium was reached within 1 min) process. The maximum saturated entrapment capacity could reach 513 mg g−1, which is higher than that of the reported two-dimensional COF. The single-component batch experiments and muti-components dynamic experiments suggested that COF-DL229 has a strong affinity towards Th (IV), but little affinity with other ions, which makes COF-DL229 a promising material for selective thorium recovery from waste solution. The interaction mechanism was Th-N coordination, which was confirmed by characterizations (Fourier Transform infrared spectroscopy, FT-IR, X-ray photoelectron spectroscopy, XPS, energy dispersive spectrometer, EDS) and density functional theory (DFT) calculations. The density of states indicated that the doping of the Th (IV) can lower the band gap of the COF-DL229, indicating higher electrical conductivity and stronger adsorption energy. The differential charge exhibited an obvious charge transfer between Th (IV) and the N atom in COF-DL229. [ABSTRACT FROM AUTHOR]

• A novel three-dimensional covalent organic frameworks (3D COFs) TpTAM coated open-tubular capillary column was developed in a simple method. • Good separation of fluoroquinolones were achieved and the TpTAM-coated columns exhibited excellent reproducibility and stability. • This research expands the application of 3D COFs as stationary phases in CEC for antibiotic chromatographic separation. The Schiff-base reaction of 1,3,5-triformylphloroglucinol (Tp) and tetra(4-aminophenyl)methane (TAM) was performed for the synthesis of a three-dimensional covalent organic framework named 3D TpTAM, which was obtained by an ultrasound-assisted method for the first time. The morphology and structure of the synthesized TpTAM were characterized through various methods. Then, TpTAM-coated capillary columns were subsequently prepared by a covalent bonding method within a short time and applied for the separation of fluoroquinolones by capillary electrochromatography (CEC) with good resolution and reproducibility. The intraday relative standard deviations (RSDs) of the retention time and peak areas were 0.88%–0.95% and 2.27%–3.81%, respectively. The interday RSDs of retention time and peak areas were 0.71%–0.89% and 0.88%–3.60%, respectively. The column-to-column RSDs of retention time and peak areas were less than 1.90% and 13.56%, respectively. The interbatch RSDs of retention time and peak areas were less than 3.48% and 3.89%, respectively. The TpTAM-coated capillary columns could be used for no less than 100 runs with no observable changes in the separation efficiency. The separation mechanism was also studied, which indicated that π-π stacking effects, hydrophobic interactions and hydrogen bonding were the main factors. The results revealed that 3D TpTAM should have superior potential as the stationary phase in CEC for chromatographic separation. [ABSTRACT FROM AUTHOR]