Reconstruction of biomimetic ionic channels within covalent organic frameworks for ultrafast and selective uranyl capture

The efficient extraction of uranium,as the primary component of nuclear energy,holds significant implications.Drawing inspiration from the charge interaction observed in biological ion channels,we encapsulated negatively charged polystyrene sulfonate(PSS)or sodium polystyrene carboxylate(PVBA)into the nanochannels of amidoxime functionalized covalent organic framework(COF-AO)in-situ to alter the cavity environment of COF-AO.The synthesized COF-AO-PSS and COF-AO-PVBA are used for ultra-fast and highly selective uranium recovery.The negatively charged PSS/PVBA was confined in the COF-AO channel providing the driving force for uranium transport and blocking other ions,thus creating a highly selective“uranium highway”.Additionally,introducing sulfonate groups or carboxyl groups into COF-AO offers supplementary coordination environments and weak interactions with uranium.Due to charge-assisted migration and various interaction mechanisms,both COF-AO-PSS and COF-AO-PVBA exhibit faster adsorption kinetics and higher selectivity compared to COF-AO alone.Their adsorption capacities are 3.8 times and 2.4 times that of COF-AO alone respectively which highlights the necessity for constructing biomimetic ion channels in uranium adsorption processes.This work presents a bionic adsorbent based on covalent organic frameworks(COFs)for the first time,overcoming environmental and equipment limitations associated with traditional photocatalysis and electrocatalysis methods for uranium capture,opening up new avenues for designing multifunctional materials that mimic biological systems.

A novel 3D sp2 carbon-linked covalent organic framework as a platform for efficient electro-extraction of uranium

Extracting uranium from seawater offers opportunities for sustainable nuclear fuel supply,but the task is quite challenging due to the low uranium concentration(~3 ppb)in seawater.Here,based on the Knoevenagel condensation reaction of aldehyde and acetonitrile groups,a novel stable sp^(2)carbon-linked three-dimensional covalent organic framework(3D COF),TFPM-PDANAO was prepared as a porous platform for uranium extraction from seawater.The TFPM-PDAN-AO designed with regular 3D pore channel of 7.12 A provides a specific channel for uranyl diffusion,which exhibits high selectivity and fast kinetics for uranium adsorption.Meanwhile,the superior stability and optoelectronic properties enable it an excellent porous platform for uranium electroextraction.By applying alternating voltages between-5 and 0 V,uranyl ions can rapidly migrate and enrich into the porous structure of TFPM-PDAN-AO,then inducing the electrodeposition of uranium compounds to form the charge neutral species(Na_(2)O(UO_(3)H_(2)O)x)with an unprecedentedly high adsorption capacity of 4,685 mg g^(-1).This work not only expands the application prospects of functionalized 3D COFs,but also provides a technical support for the electrodeposition adsorption of uranium from seawater.

Robust Colorimetric Detection of Cu^(2+) by Excessed Nucleotide Coordinated Nanozymes

Many sensors for Cu^(2+)rely on the catalytic activity of Cu^(2+)to produce a color change,but these colorimetric sensors often suffer from poor selectivity and are susceptible to interference.In this work,we found that Cu^(2+)-catalyzed TMB oxidation can be significantly improved with excessed nucleotides and nucleosides.Especially,with oversaturated guanosine 5′-monophos-phate(GMP)to form a coordination nanozyme,the catalytic efficiency was greatly accelerated.It can be attributed to the specific binding between the electron-rich oxygen and nitrogen atoms of guanine with Cu^(2+).A sensitive and selective strategy for Cu^(2+)sensing was proposed.Owing to the presence of excessed GMP,it ensures robust activity and less susceptibility to interference.This allowed us to test the sensor in complex samples such as the seawater.This work strongly suggests that by supplying excessed ligands,far exceeding the binding stoichiometry,we may produce more robust sensing systems.

Alkynyl-Based sp^(2) Carbon-Conjugated Covalent Organic Frameworks with Enhanced Uranium Extraction from Seawater by Photoinduced Multiple Effects

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-1,3,5-triyl)triacetonitrile(TN)and 4,4′-(buta-1,3-diyne1,4-diyl)dibenzaldehyde(BD)that is highly conjugated and possesses excellent photocatalytic activity.The excellent photocatalytic activity endows the BDTN-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[UO2(CO3)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.