Preamble

Synergistic Bilayer-modified Electrode Pulse Electrochemistry Efficient Uranium Extraction Seawater Jian-Yi Xiao-Mei Qin-Qin Jiang

1. I

ntroduction Nuclear power, characterized ultra-low greenhouse emissions, extensively developed decades provide large-scale electricity total power generation capacity expected increase significantly coming decades, increase demands emerging markets global population growth nuclear fuel, uranium plays indispensable nuclear cycle widely nuclear power plants worldwide However, according International Atomic Energy Agency (IAEA), known terrestrial uranium reserves insufficient rising consumption demand potentially causing supply shortages within century Given seawater contains thousand times uranium terrestrial reserves, researchers focused developing efficient extraction technologies recover uranium seawater Furthermore, uranium severe environment pollutant persistence, non-degradability, bioaccumulation potential, posing serious ecological human health risks concentrations Consequently, effective separation, enrichment, reuse uranium contaminated sources emerged crucial complementary strategy, serving purposes sustainable nuclear acquisition environmental remediation Physicochemical adsorption electrochemical

methods

utilized uranium extraction, where capacity, kinetics selectivity general evaluation criteria Physicochemical adsorption, taking phosphate- amidoxime- functionalized materials prominent reagents, immobilizes uranium adsorbent surfaces limited adsorption kinetics competitive cation adsorption (e.g., contrast, electrochemical extraction garnered significant interest superior uranium enrichment capacity, extraction kinetics driven electric field, selectivity enabled adjusting voltage, compatibility device integration miniaturization Moreover, offshore tidal solar energy conversion technologies reached large-scale commercial deployment (e.g., projects StEnSea), development would provide practical power supply electrochemical extraction processes Uranyl dominant uranium seawater nuclear wastewater, possesses axial oxygen atoms coordination sites equator plane Coordination reactions equatorial plane thermodynamically favorable, common ligands including Among these, exhibits strongest binding affinity uranyl combined electronic structural effects. seawater 8.1), concentration (~0.15 approximately orders magnitude higher uranyl, leading preferential formation uranyl-carbonate complexes thereby hinder uranyl immobilization physicochemical adsorption modulating applied voltage, cathodes provide tunable electron donation uranyl overcome interference extraction uranium seawater crucial sustainable nuclear energy remains challenging concentration, carbonate competition, energy-intensive processes.

Herein, study developed systematically evaluated novel electrode material, CF@MTPN, coupled energy-efficient double potential technique (DPST) highly efficient extraction uranium seawater.

CF@MTPN fabricated through sequential self-assembly iron-tannic (Fe-TA) network iron-phytic (Fe-PA) complex carbon felt. simulated seawater uranyl, 8.1), CF@MTPN achieved rapid uranium removal efficiencies 90.3% (potentiostatic technique 93.3% (DPST) within extraction capacities respectively.

Notably, during process current oscillations detachment Fe-PA layer control electrode CF@MPN, alongside progressive oxidation surface. contrast,

introduction

inner Fe-TA layer CF@MTPN effectively resolved these stability issues, allowing CF@MPN maintain structural integrity throughout extended operation.

Moreover dramatically enhanced Faradaic efficiency effectively suppressing competing hydrogen evolution reaction.

Practical viability confirmed through continuous-flow

experiment

natural seawater, achieving uranium recovery extraction capacity presents synergistic material process solution efficient, stable, energy-conscious uranium extraction seawater. eywords Seawater uranium extraction lectrochemical extraction ouble potential technique hytic ron-tannic network

However, seawater contains abundant competing cations (e.g., which inhibit uranyl electrosorption electrostatic screening action effect.

Recent studies employed high-frequency pulsed strategy mitigate interference non-target species water splitting However, during pulsed electrochemical process, interruption electric field

result

reverse current, accompanied progressive oxidation, electrode passivation, other undesirable changes surface properties.

Enhancing electrode stability therefore requires disrupting these self-sustaining feedback loops, which achieved through strategic electrode material modification precise control potential window. address these stability challenges while maintaining affinity uranyl, turned bilayer electrode design leveraging complementary properties phytic tannic phosphate groups flexible skeleton, effectively multidentate chelates uranyl presence concentration oreover, irreversible oxidation produces forms crystalline precipitate.

Although easily soluble water, employed functional layer electrode materials (e.g., adsorbing conductive substrates polypyrrole polyaniline strong electrostatic interactions) electrochemical uranium extraction Unfortunately, under acidic conditions easily desorbed these substrates.

Under alkaline conditions phosphoester (P-O-C) susceptible hydrolysis, resulting structural collapse function. electrochemical reaction, hydrolysis P-O-C accelerated oxidation current associated electrochemical oscillation, leading stability phase separation electrode material.

Fe-TA networks reported promising materials various research fields their compatibility, responsiveness, adsorption capacity, synthesis, excellent stability range Fe-TA networks tunable buffering systems maintain local altering their coordination states, exhibiting approximately twofold fourfold higher buffering capacity polyelectrolyte complexes commercial buffer solutions, respectively Furthermore, their abundant hydroxyl groups (-O-H) multiple hydrogen bonds groups leading robust immobilization under high-voltage low-pH conditions Physical entanglement further enhances stability immobilization.

Similarly, Fe(III) cross-linkers between (and/or molecules, forming macromolecular networks (denoted significantly enhance immobilization stability resistance hydrolysis presents PA-functionalized CF@MTPN electrode, which efficiently extracts uranium while exhibiting resistance interference concentrations Additionally, exhibits intriguing electrochemical oscillatory phenomenon during pulsed electrochemical process, characterized significantly weaker progressive oxidation passivation compared CF@MPN.

Electrochemical

analysis

revealed significantly enhanced reversibility electro-oxidation CF@MTPN compared CF@MPN, highlighting critical Fe-TA layer.

Moreover, CF@MTPN demonstrates electrical conductivity, electric double-layer (EDL) capacitance, superb hydrophilicity, excellent ability generate Fe(OH) flocs [Fe(CN) solution electroflocculation.

Through systematic optimization, significantly improved electrode performance overcoming inherent limitations traditional materials, concentration, carbonate competition, energy-intensive processes.

Furthermore, refining electrochemical extraction process through operational potential optimization, enhanced extraction efficiency resource recovery rates.

Compared existing technologies, approach demonstrates superior performance provides theoretical practical innovations. study expands methodological repertoire uranium resource extraction contributes novel solutions clean energy development, thereby supporting sustainable advancement nuclear power technologies.

2. M

aterial

2.1. C

hemicals chemicals least reagent grade without further purification.

Detailed information these chemicals provided Supporting Information (Text

2.2. E

lectrode reparation electrodes fabricated pre-cleaned carbon sequential coordination-driven self-assembly process. design features robust Fe-TA network inner stabilizing layer, followed Fe-PA complex outer uranium-binding layer. cleaned piece immersed aqueous solution Subsequently, solution added initial Fe-TA coordination network gentle vortexing.

Fe-TA network substrate stabilized adding buffer 7.4).

After standing piece retrieved thoroughly rinsed deionized water ethanol, yielding intermediate product CF@MTN. as-prepared CF@MTN further functionalized immersing solution Then, solution added cross-link followed brief vortexing standing.

Subsequently, buffer added complete assembly Fe-PA.

After aging thorough washing, final product obtained denoted CF@MTPN. electrochemical measurements, electrode (exposed area: secured clip. average CF@MTPN electrode comparison, control electrode without inner Fe-TA layer prepared. piece directly subjected PA/FeCl coating procedure described above second CF@MTPN synthesis. sample, designated CF@MPN, elucidate critical Fe-TA inner layer enhancing electrode stability.

2.3. Characterization

Scanning electron microscopy (SEM) imaging performed Gemini field-emission microscope (Zeiss, Germany) operating accelerating voltage Transmission electron microscopy (TEM) conducted Talos F200S microscope (FEI, X-ray diffraction

(XRD) patterns collected using X'Pert diffractometer (Rigaku Smartlab, Japan) radiation.

X-ray photoelectron spectroscopy (XPS) measurements acquired Scientific K-Alpha spectrometer (Thermo Fisher, USA). potentials determined Surpass Electrokinetic Analyzer (Anton GmbH, Austria).

Water contact angles measured ambient temperature (~30% humidity) sessile

method

using JY-PHa instrument (China). UV-Vis absorption spectra recorded UV-2700 spectrophotometer (SHIMADZU, Japan).

Fourier transform infrared (FTIR) spectra obtained using Nicolet spectrophotometer (Thermo Fisher, USA). concentration uranium adsorbed material surfaces quantified inductively coupled plasma spectrometry (Agilent 7900, USA). values electrolytes measured PHS-2F meter (Leici, China).

Electrochemical measurements, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), performed electrochemical workstation (China) employing standard three-electrode system.

2.4. Electrochemical

measurements electrochemical measurements performed using electrochemical workstation under ambient conditions standard three-electrode configuration. working electrodes as-prepared samples secured clips. saturated calomel electrode (SCE, saturated employed counter reference electrode, respectively. conducted rates respectively, unless otherwise stated. measurements carried [Fe(CN) [Fe(CN) (1:1) solution frequency range potentials reported versus unless specified.

2.5. Uranium

xtraction erformance uranium concentration solution quantified using complementary techniques selected based solution matrix. solutions without carbonate interference, concentration residual determined arsenazo colorimetric

method

solutions containing carbonate, which interferes colorimetric assay, inductively coupled plasma optical emission spectrometry (ICP-OES) employed. experiments performed triplicate, reported average values. uranium extraction efficiency (Removal, calculated using Equation Where initial concentration concentration

2.6. Physicochemical

dsorption

experiment

adsorption experiments conducted temperature. Three piece sample each) added uranyl solution under constant stirring. predetermined intervals, aliquots solution withdrawn. residual uranium concentration these aliquots analyzed ICP-OES. uranyl removal efficiency calculated according Equation experiments performed triplicate, reported average values.

3. R

esults

3.1. Material

haracterization resolution Scanning elemental mapping images patterns CF@MPN spectra regions spectra Contact angles water surfaces after dripping Nyquist plots images reveal CF@MTPN exhibits fibrous morphology diameter rough surface decorated numerous irregular nanoparticles (Fig. study formation process CF@MTPN, elemental mapping investigat surface element distribution intermediate CF@MTN final CF@MTPN.

After self-assembly Fe-TA complex resulting CF@MTN shows uniform distributions elements (Fig.

Subsequent self-assembly Fe-PA complex CF@MTPN resulted homogeneous distribution (Fig. spectrum CF@MTPN confirms presence surface, weight percentages (wt.%) 1.62, respectively (Fig. shown patterns CF@MTN CF@MTPN exhibit broad peaks (002) (100) crystal plane carbon, respectively absence diffraction peaks after surface coating, compared pristine suggests Fe-TA Fe-PA coatings amorphous nature. survey spectrum CF@MTPN confirms presence surface (Fig. spectrum (Fig. corresponds phosphate ester group (-OPO spectrum (Fig. deconvoluted components C-O/P-O-C bonds, further verifying successful anchoring Fe-PA complex surface. shown spectrum (Fig. multiplet splitting presents characteristic satellite features located approximately above their respective peaks. spectrum fitted peaks characteristic Fe(II) (714.

Fe(III) (710.

spectroscopy employed further confirm successful modification. spectrum CF@MTN (Fig. shows peaks ascribed stretching vibration aromatic skeleton vibration respectively, indicating formation Fe-TA complex Similarly, spectrum CF@MTPN (Fig. exhibits characteristic peaks assigned P-O-C vibrations respectively, confirming successful incorporation Fe-PA complex. significant drawback carbon-based materials electrochemical applications their inherent hydrophobicity, fraction surface wetted electrolyte contributes overall performance evaluate property, sessile

method

conducted compare wettability CF@MTN, CF@MPN CF@MTPN. shown pristine hydrophobic, water contact angle contrast, Fe-TA coating rendered CF@MTN hydrophilic contact angle decreasing within droplet deposition.

CF@MPN, functionalized Fe-PA, showed enhanced hydrophilicity contact angle decreasing within droplet deposition.

Remarkably, CF@MTPN featuring bilayer Fe-TA Fe-PA demonstrated superhydrophilic behavior. interfacial wettability intrinsically linked electrochemical processes.

Charge transfer dynamics, including specific adsorption, surface redox reactions, complex interfacial interactions between electrode, electrolyte ions, solvent molecules, collectively influence surface tension wettability often represented Nyquist plots, powerful technique characterizing these parameters revealing interfacial structure electrode/electrolyte interface illustrates

results

CF@MTN, CF@MPN, CF@MTPN, measured alternating-current amplitude open-circuit potential. charge transfer resistance derived semicircle diameter fitting equivalent circuit model (Fig. using Zview software, below electrodes, indicating highly efficient interfacial charge transfer.

3.2. Electrochemical

characterization potential water. curves solution different rates. valuation capacitance Voltammograms recorded CF@MTN, CF@MPN CF@MTPN various rates electrolyte contain [Fe(CN) (inset) igital photo solutions before after reaction. spectra [Fe(CN) obtained precipitate. calibration curve between current square [Fe(CN) redox reaction curves solution containing different concentrations uranyl.

Scanning elemental mapping images shown potentials water measured respectively. significantly negative potentials modified electrodes indicate successful coating, which introduces abundant negatively charged functional groups (e.g., phenolate phosphate). enhanced surface negativity expected favor sorption cationic uranyl species. electrochemical properties these electrodes further evaluated measurements [Fe(CN) shown curve CF@MTPN shows prominent redox couple, oxidation reduction [Fe(CN) redox reaction. shapes suggest CF@MPN CF@MTPN might lower electroactive surface areas potentially faster electron transfer kinetics CF@MTN. capacitances electrodes evaluated using various rates CF@MTN:

CF@MPN: CF@MTPN: hydrophobic exhibited capacitance CF@MTN, coated Fe-TA networks showed highest capacitance CF@MPN, coated Fe-PA complex, lower capacitance Notably, CF@MTPN, featuring Fe-TA Fe-PA layers, displayed intermediate capacitance intermediate value suggests outer Fe-PA layer CF@MTPN partially limit access underlying Fe-TA layer compared CF@MTN voltage window expanded profiles CF@MTN, CF@MPN, CF@MTPN [Fe(CN) revealed significant change: reduction emerged approximately (Fig. which attributed reduction Fe(III) species. shows curve CF@MTPN alongside photographs solution before after reaction. yellow precipitate formed continuously during (Fig.

analysis

precipitate (Fig. showed characteristic peaks assignable Fe(OH) [Fe(CN) investigate reaction kinetics, currents plotted against square oxidation current [Fe(CN) exhibited linear relationship 3.63, 0.998), reduction current [Fe(CN) 3.65, 0.999) (Fig.

These linear dependencies confirm oxidation reduction processes diffusion-controlled similar electrodeposition phenomenon observed CF@MTPN uranyl nitrate solution. shown current approximately increase gradually increasing uranyl concentration.

SEM-EDS mapping electrode after (Fig. revealed uniform distribution elements, confirming effective co-deposition enrichment uranium.

3.3. Electro

chemical ranium xtraction

curves electrodes solution containing uranyl. spectrum after curves which chelate different metal which chelate ifferent quantities Fe(III). curves which chelate different metal which chelate ifferent quantities Fe(III). comparison, electrochemical behavior uranyl evaluated CF@MTN, CF@MPN, CF@MTPN electrodes containing uranyl While distinct redox peaks observed curves CF@MTN CF@MPN, CF@MTPN exhibited well-defined redox peaks (Fig. highlighting superior activity uranium electrodeposition.

analysis

employed investigate chemical states elements CF@MTPN electrode surface before after uranium electrodeposition (Fig. survey spectra revealed emergence peaks after electrodeposition, respectively, confirming successful uptake uranium.

High-resolution scanning region (Fig. indicated presence mixed valence states, including U(IV), U(V), U(VI).

Based combined results, cathodic approximately attributed reduction U(VI) lower valence states, while likely associated electrochemical adsorption uranyl species electrode surface. quantitatively evaluate uranium extraction performance electrodes, concentration uranyl electrolyte monitored using arsenazo colorimetric method. calibration curve arsenazo

method

established using standard uranyl solutions prepared absence carbonate (Fig.

S10a), which exhibited excellent linear relationship 0.07509x 0.01323, 0.999) (Fig.

S10b). further investigate electrodeposition behavior, performed different electrodes using setup shown optimization began outer Fe-PA layer (with resulting electrodes denoted CF@MTP choice metal center significantly influenced electrochemical response, Cu(II) Fe(III) yielding highest reduction current associated uranyl adsorption (Fig.

Furthermore, optimization molar ratio Fe(III) revealed ratio generated maximum current response (Fig.

Subsequently, inner Fe-TA layer optimized separately (with resulting electrodes denoted CF@MT Similarly, choice metal center critical, again showing Cu(II) Fe(III) effective (Fig. molar ratio Fe(III) found optimal yielding strongest signal uranyl adsorption (Fig.

Based practical advantage easier separation, ultimately selected copper metal center coordination layers. control

experiment

CF@MPN (which contains Fe-PA layer lacks Fe-TA inner layer) confirmed vital bilay structure showed significantly weaker response (Fig.

S12). schematic overall preparation process CF@MTN CF@MPN CF@MTPN provided curves CF@MTPN without uranyl. hronoamperometric curves uranyl removal efficiency charge consumption potentiostatically enhanced adsorption process using CF@MTPN influence electrochemical physicochemical adsorption ranium extraction performance electro chemical adsorption CF@MTN CF@MPN CF@MTPN curves CF@MTN CF@MPN CF@MTPN consecutive rounds electrochemical oxidation initiative reduction mechanization these electrode

The LSV curves of CF@MTPN (Fig. 4 [FIGURE:4] a) revealed a significantly higher current density in the presence of 5 mg L − 1

uranyl potentials negative indicating additional electron consumption uranyl reduction/adsorption. hronoamperometric tests conducted controlled potentials (Fig. orresponding uranium removal rates charge consumed displayed identifying optimal potential. optimal potential, CF@MTPN exhibited rapid extraction kinetics, removing uranyl within (Fig.

S13). absence carbonate, electrochemical process achieved extraction capacity which significantly superior physicochemical adsorption alone, which achieved removal capacity presence minor inhibitory effect electrochemical adsorption greater impact physicochemical process (Fig.

Quantitatively, electrochemical extraction capacity presence carbonate remained whereas physicochemical adsorption capacity Furthermore, responses CF@MTN, CF@MPN, CF@MTPN differed significantly (Fig.

S14), which translated marked differences adsorption performance. uranyl removal efficiencies after 32.3%, 29.2%, 96.3% CF@MTN, CF@MPN, CF@MTPN, respectively, unequivocally

demonstrating superior performance bilayer CF@MTPN electrode (Fig. elucidate differences adsorption performance, surface properties CF@MTN, CF@MPN, CF@MTPN investigated using consecutive first cycles (Fig. revealed distinct behaviors: exhibited current; CF@MTN CF@MTPN showed strong oxidation peaks respectively; CF@MPN displayed

Analysis

multiple cycles provided insights redox processes. exhibited current stepwise oxidation above (Fig.

CF@MTN, consecutive cycles (Fig. revealed reversible oxidation attributable hydroxyl group oxidation. spontaneous reduction current interrupting electric field indicates excellent surface antioxidant capacity reversible electron/proton transfer process. oreover, progressive increase oxidation reduction current cycles suggests activation process, likely enhanced accessibility rather electrolyte migration. behavior CF@MPN differed significantly (Fig. initial anodic assigned electric-field-promoted hydrolysis neutral hydrolysis generates hydroxyl groups, which oxidized subsequent cycle followed spontaneous reduction.

Notably, CF@MTPN exhibited strong initial oxidation (Fig. which would attribute hydroxyl group oxidation, positive shift compared subsequent cycles (0.40 being transport effects. consistent observation spontaneous reduction confirms regeneration hydroxyl groups underscores superior antioxidant capacity compared CF@MPN, better reversibility CF@MTN.

conclusion

further supported tenth cycles (Fig. S16), which CF@MTPN maintains highest concentration electroactive hydroxyl groups. curves CF@MTPN electrolyte effect uranyl addition hronoamperometric curves CF@MTPN during processes controlled potentials ranging Performance CF@MTPN processes uranium extraction efficiency shows operating procedure DPST.

analysis

electrolytes process using fresh CF@MTPN electrode.

Pulsed current profiles CF@MTPN first minute steps respectively.

Chronoamperometric curves CF@MPN during shown addition obscure clear differences curves CF@MTPN without uranyl, indicating sustained electron consumption attributable uranium extraction.

Subsequently, potentiostatic (PST) double potential (DPST) techniques employed extract uranium simulated seawater uranyl, 8.1). present chronoamperometric curves processes CF@MTPN potentials electrode current increased significantly time, which attributed sharp solution promotes hydrogen evolution reaction (HER). likely

results

vigorous oxygen evolution counter electrode (Fig. S17).

Visible hydrogen bubbles CF@MTPN electrode (Fig. further confirm significant activity. energy efficiency standpoint, undesirable competing reaction should minimized.

Pulse oltammetry widely employed numerous studies mitigate issue Figs. chronoamperometric curves process CF@MTPN frequency power-on power-off ratio compares during processes, inset illustrating operating procedure DPST. process exhibit stable currents significantly lower compared along highly efficient uranium extraction (Fig.

CF@MTPN achieved uranium removal efficiencies 90.3% 93.3% using

methods

respectively. extraction capacities DPST. importantly, optimal potential enhanced Faradaic efficiency compared calculated values. dramatic enhancement underscores superior energy efficiency pulsed electrochemical approach. further assess solution after electrochemical extraction, electrolyte obtained process analyzed using fresh CF@MTPN electrode (Fig. reduction current intensity decreased following order based potential applied during electrolyte generation: trend demonstrates spent electrolyte processes negative potentials contains residual uranyl, confirming extraction efficiency.

Moreover, sensitive response electrode varying uranyl concentrations highlights potential detecting uranyl carbonate-containing aqueous solutions. displays pulsed current profile CF@MTPN during initial minute process (periodically switching between current oscillates periodically, amplitude stabilizing after approximately Notably, reverse current observed immediately switching applied voltage. attributed discharge electrical double layer (EDL), cations (e.g., migrated cathode under electric field diffuse solution. similar current behavior observed CF@MTN CF@MPN (Figs.

S26), consistent universal formation relaxation mechanism. cathodic potential increased current amplitude CF@MTPN stabilized rapidly (Fig. case, reduction current amplitude significantly exceeded oxidation current, indicating Faradaic processes uranyl reduction contribute alongside charging.

Crucially, digital

photos electrode during process visible bubbles (Fig.

S27). direct comparison process (Fig. S18), where vigorous evident, process effectively suppresses undesirable reaction. separate experiment, process (periodically switching between applied resulted gradual increase pulsed current amplitude (Fig.

S28). suggests progressive electrochemical oxidation originally hydrophobic surface, rendering hydrophilic. transformation confirmed contact angle measurements, showing decrease after (Fig.

S29). shown pulsed current conditions lower CF@MTPN CF@MTN consistent inferior wettability lower capacitance.

CF@MTN exhibited higher pulsed current CF@MTPN which correlates higher capacitance.

CF@MTN CF@MTPN, reduction current amplitude exceeded oxidation current, indicating concurrent Faradaic reduction reactions alongside capacitive charging. shows chronoamperometric curve CF@MPN during process. current amplitude remained stable first Around point, sharp decrease occurred, accompanied visible detachment modification layer electrode.

Subsequently, current behavior resembled gradually increasing exposed carbon fiber surface oxidized. superior performance CF@MTPN extraction attributed synergistic effect Fe-TA layer technique.

Fe-TA layer enhances uranium extraction efficiency significantly improves electrode stability, evidenced intact structure after testing compared severe detachment observed CF@MPN electrode.

Moreover, process itself factor enhancing energy efficiency.

CF@MTPN during significantly lower during while still achieving extraction efficiency. combination energy input output, coupled observed absence bubbles electrode surface, confirms process effectively mitigates compared conventional method.

Performance valuation atural eawater Reaction device continuous uranium extraction natural seawater spectrum Scanning elemental mapping images CF@MT periodically switch between frequency power-on power-off ratio validate practical applicability extraction

method

based CF@MTPN electrode, continuous-flow reaction system (Fig. employed extract uranium natural seawater. setup, circulation transported seawater reservoir electrochemical reaction back, maintaining dynamic constant Liquid phase delivered anode cathode using air-liquid hybrid peristaltic pump, respectively.

After continuous operation, chemical state extract uranium CF@MTPN electrode investigated shown recovered uranium predominantly state. elemental mapping (Fig. confirmed homogeneous distribution electrode surface. spectrum (Fig. showed 0.90, respectively. electrode subsequently regenerated immersion solution ICP-OES

analysis

eluent determined total amount recovered uranium extraction efficiency 90.88%. calculated extraction capacity (0.086 which compares favorably reported adsorbents electrocatalytic materials seawater uranium extraction (Table Regeneration solution effectively restored composition CF@MTPN, shown spectroscopy (Fig. which indicated 88.32% 9.75% 0.09% 1.84% (Fe). imaging (Fig. confirmed morphology regenerated CF@MTPN remained similar pristine electrode. excellent regenerability further corroborated (Fig. (Fig. analyses, which showed nearly identical spectra before after Finally, curve regenerated electrode simulated seawater (Fig. exhibited clear enhancement current density presence uranyl, confirming retention electrochemical activity uranium extraction.

4. Conclusion

study successfully developed systematically evaluated novel electrode material, CF@MTPN, coupled electrochemical highly efficient extraction uranium seawater. bilayer modification structure CF@MTPN, fabricated through sequential self-assembly Fe-TA Fe-PA complexes demonstrated superior performance. simulated seawater uranyl, 8.1), CF@MTPN achieved optimal efficiencies 90.3% 93.3% uranium removal within using methods, respectively. extraction capacities (2.28 (2.36 DPST.

Notably, enhanced Faradaic efficiency uranium extraction compared significant improvement successfully addresses energy efficiency issue inherent caused competing stable current absence bubble formation electrode surface during collectively demonstrat operational stability. oreover, substantially lower confirms energy effectively directed toward target uranium extraction reaction rather reactions. practical viability system demonstrated

continuous-flow

experiment

using natural seawater. uranium extraction efficiency 90.88% achieved, extraction capacity which compare favorably reported adsorbents electrocatalytic materials Moreover, electrode could efficiently regenerated regenerated electrode largely retaining original morphological mpositional, electrochemical properties. summary, work, through innovative electrode design advanced electrochemical process, provides effective promising solution challenges seawater uranium extraction namely, carbonate inhibition, stability, energy consumption. establishes solid theoretical technical foundation sustainable recovery valuable potentially hazardous metals.

Declarations Conflict interest authors declare competing interests

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