Interfacial water dissociation at the bipolar junction is the governing physical process that determines the energy efficiency of bipolar membranes. However, how the local physicochemical environment quantitatively controls this dissociation barrier remains poorly understood. Theoretically, the dielectric constant modulates the strength of electrostatic interactions: a high dielectric constant screens the Coulombic attraction between nascent H+ and OH- ions, facilitating charge separation, whereas a low dielectric constant stabilizes ion pairs, necessitating a higher voltage to sustain dissociation. Simultaneously, water activity sets the thermodynamic baseline for the reaction. In this study, we utilize water-alcohol mixtures as a tunable solvent platform to quantitatively separate and compare these two effects within a physics-guided semi-empirical framework. By combining thermodynamic principles with a physics-guided junction model, we reveal a fundamental mechanistic transition. In methanol and ethanol mixtures, dielectric and water-activity effects contribute additively to the voltage drop. Crucially, in the hydrophobic isopropanol system, we identify a pronounced synergistic coupling: the low-dielectric environment significantly amplifies the thermodynamic penalty of reduced water activity. This finding clarifies the physical origin of the sharp voltage escalation in hydrophobic media. Overall, this work provides a compact quantitative framework for understanding how the dielectric-activity interplay sets the effective dissociation barrier, offering a theoretical basis for optimizing bipolar membranes in diverse solvent environments.

Designing monovalent ion-selective membranes (MISMs) with high permeability and selectivity is challenging yet desirable for efficient and sustainable ion separation processes. Conventional MISMs with homogeneously or compositely charged architectures depend on steric hindrance or Donnan repulsion to inhibit divalent ions. However, inherent ion transport limitations of these architectures result in the well-known permeability-selectivity trade-off. Herein, we present an asymmetrically charged membrane (ACM) that regulates the ion transport mechanism to simultaneously enhance both permeability and selectivity. The ACM features an asymmetric charge distribution, with a low-charge-density surface sieving layer and a high-charge-density sublayer that reduces transport resistance while synergistically liberating transport sites within the sieving layer. Compared to the homogeneous membrane, the optimal ACM achieves a 2.5-fold enhancement in Cl /SO4 2 selectivity and a 10-fold reduction in Cl membrane resistance, enabling the recovery of 99.92 wt%-purity NaCl from industrial high-salinity wastewater. The concept of asymmetrically charged topology provides a novel design framework for the next-generation MISMs.

The development of efficient separation technologies for Bi3+ is highly desirable to meet the increasing demand for technology-critical bismuth. In this study, bis(2-ethylhexyl) phosphate (HDEHP)-functionalized pore-filling membranes were fabricated for the efficient separation of Bi3+ and Cu2+ via electrodialysis. Microstructural and chemical characterizations demonstrated the superior compatibility between HDEHP and the polymer chains. The tight arrangement of functional groups within the membrane established a continuous transport pathway for metal ions, enabling selective separation of Bi3+ via an ion-exchange process. Under optimal conditions, the Bi3+ flux reached 2.6 mmol m-2 h-1 with an outstanding perm-selectivity P Cu2+ Bi3+ of 26.3 during electrodialysis. Moreover, the separation efficiency could be further improved by increasing the number of repeating membrane units, laying a foundation for practical industrial applications. This work provides a promising candidate for the efficient and convenient selective recovery of technology-critical metals from industrial wastewater.

Electrodialysis (ED) based on ion-exchange membranes (IEMs) has recently attracted increasing attention for high-salinity wastewater treatment, concentrated seawater resource recovery, and selective ion separation. However, the performance of conventional ED stacks in these areas remains constrained by the intrinsic selectivity of membrane materials and mass-transport limitations, preventing them from fully meeting practical requirements in terms of separation efficiency and energy consumption. Rational design of ED modules can partly overcome these shortcomings, for example by optimizing feed configurations to enhance selective ion redistribution or by tailoring membrane stacking sequences within the stack to realize differentiated ion sieving. In addition, integration with other separation processes can provide synergistic advantages and further improve overall system performance. This review advances the perspective that stack and configuration design constitutes an independent and powerful design dimension in ED, alongside membrane materials and operating conditions. By focusing on the influence and limitations of key structural parameters, and highlighting recent advances in innovative designs such as selectrodialysis, ladder ED, and ion-”distillation”, it shows how configuration-enabled strategies can fundamentally reshape ion-transport pathways, redistribute driving forces, and unlock performance regimes unattainable by material optimization alone. Furthermore, the emerging roles of multiphysics coupling and data-driven modeling in elucidating ion-transport mechanisms and guiding stack-level performance optimization are critically assessed. Finally, we outline future research directions in ED stack design and process integration to guide the development of next-generation ED technologies toward more energy-efficient, selective, and scalable desalination and resource recovery processes.

High-entropy spinel oxide (CrMnFeCoNi)3O4 has emerged as a promising electrode material for vanadium redox flow batteries (VRFBs). In this work, a spinel-structured CrMnFeCoNi)3O4/reduced graphene oxide (rGO) nanocomposite was synthesized via a hydrothermal process followed by thermal reduction. (CrMnFeCoNi)3O4 nanoparticles on rGO produce a strong synergistic effect, providing abundant redox-active sites and fast ion transport to enhance charge-transfer kinetics, reversibility, and stability. Its stable spinel structure, uniform cation distribution, and the presence of multivalent ions further enhance redox activity. Comprehensive char-acterization confirmed the formation of a complete spinel phase with uniform elemental distribution. Notably, EXAFS analysis revealed a disordered local structure with reduced coordination and slight bond shifts, indicating that lattice distortion and oxygen vacancies reinforce defect stability. In addition to ICP-OES confirmation, these features ensure strong structural and chemical stability during cycling. Consequently, the (CrMnFeCoNi)3O4/ rGO-modified electrode achieved a high energy efficiency of 87.14 % at 80 mA cm-2 and maintained excellent stability over 300 cycles at 200 mA cm-2. This work presents a viable route to advance VRFB electrodes and to improve multicomponent, defect-rich materials for energy storage.

Metal alkoxides are widely applied in organic synthesis because of their solubility and volatility. However, conventional synthetic methods suffer from safety risks, harsh conditions, and low efficiency. This study reported the first evidence of isopropanol dissociation in a bipolar membrane and developed a green electrosynthesis route for lithium isopropoxide by taking advantage of isopropanol dissociation in bipolar membranes. We find that the threshold dissociation voltage of isopropanol was 53.4 V, which is significantly higher than that of water and C1/C2 alcohols because of its low dielectric constant. To overcome high solution resistance, various electrolytes have been screened, with tetraethylammonium chloride resulting in an 88 % reduction in stack resistance. Under the optimized current of 6 mA center dot cm-2 with the BP-A configuration, lithium isopropoxide was synthesized with an energy consumption of 213 kWh center dot kg-1 and a current efficiency of 67 %. The product was characterized via FTIR and solid-state 7Li NMR, confirming the successful formation of lithium isopropoxide. The technoeconomic analysis demonstrated that the bipolar membrane electrodialysis (BMED) process offers a costeffective and energy-efficient alternative to traditional methods, with a production cost of $51.35/kg, which is significantly lower than that of the traditional synthesis route. This study expands the application of BMED in C3 alcohols and offers theoretical and technical foundations for scalable and green production of metal alkoxides via alcohol dissociation.

Deuterated acids/bases are high-value bulk chemicals used for synthesizing deuterated pharmaceuticals1,2, modifying optoelectronic materials3 and mediating hydrogen isotope exchange reactions4,5. However, conventional synthesis methods require harsh reaction conditions with high energy consumption6,7. Here we propose a versatile platform that takes advantage of heavy water dissociation in bipolar membranes (BPMs) to produce deuterated acids and bases under particularly mild conditions. Specifically, D2SO4 (2.75 mol l-1) and KOD (5.82 mol l-1), which are comparable with commercial products, were prepared using inexpensive D2O and K2SO4. We find that the deuteron generation rate is approximately 1.25 times greater than that of the protons, which is attributed to less co-ion leakage of D+ than H+ through the anion-exchange membrane (AEM), lower salt leakage within BPMs in D2O than in H2O and lower dehydration barrier of deuterons than proton clusters in the membrane phase. Compared with other contributing factors, salt leakage plays a relatively minor role in the observed H+/D+ concentration difference. This flexible and robust platform facilitates the synthesis of various deuterium-labelled compounds.

The ion gating effect is crucial for numerous biological processes and provides valuable insights for the development of nanoscale artificial ion gates. Traditionally, ionic current rectification is achieved by designing asymmetric geometries or charge distributions via complex and cumulative procedures. Here, we report a simple aqueous immersion method for the fabrication of single-layer rectifying membranes. The prepared membrane exhibited a homogeneous distribution of positively and negatively charged groups in the interior and an asymmetric distribution of cationic and anionic groups on the two opposing surfaces, thereby enabling a satisfactory rectification effect for a variety of ions. These results indicate that the rectification ratio strongly correlates with the ion type and the ionic strength. The rectification ratios generally followed the order of Na3PO4 > Na3C6H5O7 > Na2SO4 > NaCl > KCl. Further analysis reveals that rectification efficiency is concentration-dependent. At lower concentrations (e.g., <100 mM), limited ion mobility reduces rectification performance, whereas higher concentrations (>100 mM) compress the electric double layer (EDL), diminishing charge selectivity. Optimal rectification is achieved at 100 mM ion concentration. This method provides a straightforward and viable solution for developing ion-selective membranes for ionic current rectification.

In this study, organic solutions (30-120 mg/L HA, BSA or SA) and composite solutions (5.93-10.15 wt% inorganic salts with 75 mg/L HA, BSA or SA) were used to investigate the membrane fouling behavior in the vacuum membrane distillation (VMD) system. The different permeate flux attenuation and fouled membrane morphology implied distinct membrane fouling mechanisms during VMD process. Furthermore, we employed the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory as an effective approach to analyze membrane fouling mechanisms. The results showed that the total interaction energy was negative (attraction) within the separation distance of 1-2 nm by applying the XDLVO approach, indicating that a pristine membrane was more prone to fouling. Finally, we elucidated distinct membrane fouling mechanisms in the VMD system. The inorganic feed solution readily induced inorganic fouling on the membrane surface and pore wetting, while organic feed solution and combined feed solution did not cause membrane wetting, conversely, only organic fouling and combined fouling were identified on the membrane surface. This study was expected to facilitate understanding of membrane fouling mechanisms in the VMD process.

Efficient separation of technology-critical bismuth from diverse waste streams and mineral processing is of high significance. However, Bi(III) coexists with various metal ions that have similar physicochemical properties, making its selective recovery challenging. Herein, tertiary amine-functionalized polymeric membranes with prominent bismuth separation performance are fabricated using a solvent casting pore-filling method. The excellent compatibility between the trioctylamine and polymer chains facilitates the construction of continuous ion channels, thereby enabling highly efficient and selective separation of Bi(III) during electrodialysis. The fabricated membrane achieve a great Bi(III) flux of 131.0 x 10-2 mmol m-2 h-1 and ultrahigh perm-selectivity values (i.e., PBi(III) Cu(II) = 483.9, PBi(IIINi(II) ) = 40499.7, PBi(IIICo(II) ) = 27663.1, PBi(IIIFe(III) ) = 378.3, CrPBi(III(III) ) = 819.1, PBi(III) Mn(II) = 2014.9, and PBi(III) Al(III) = 505.6) in the presence of multiple metal ions, which is much superior to that of flagship commercial AGU. The good stability of the membrane demonstrates bright prospects for realizing efficient bismuth recovery in industrial-scale applications.

Alcohol dissociation (ROH -> RO-+ H+) in the bipolar membrane (BPM) allows the in-situ generation of alkoxides under extremely mild conditions for various electrochemical synthesis. However, there is no straightforward evidence to support alcohol dissociation in C2+ alcohols, and the dissociation behavior of BPMs in a mixed alcohol solution is unknown. In this study, we provide direct evidence of ethanol dissociation in BPMs via the electrochemical production of Mg(C2H5O)2 from MgCl2. By simultaneously regulating the interface concentration and electric field strength, we infer that the aggregation of hydroxyl groups in the mixed alcohols causes ethanol molecules to tend to form cage structures around methanol molecules at relatively high concentrations, restricting the diffusion of methanol molecules into the interfacial layer of the BPMs. The solvent dissociation behavior of mixed alcohols paves the way for the application of bipolar membrane electrodialysis (BMED) in electrosynthesis and in the separation of azeotropic and homologous compounds.

Currently, bipolar membrane electrodialysis (BMED) is recognized as an eco-friendly technique to recycle lithium from waste lithium-ion batteries. However, the application of ordinary bipolar membranes has the disadvantage of unsatisfactory product purity due to undesired ion leakage. Herein, we proposed isolation chamber bipolar membrane electrodialysis (ICBMED) to inhibit coion migration, thereby increasing the purity of the regenerated acid and alkali. The experimental results indicate that 97.7%-99.3% of the LiOH generated by the ICBMED using domestic membranes was generated, which is much greater than the 85.7%-94.4% obtained without an isolation chamber. The total cost of the ICBMED for LiOH production with inexpensive domestic membranes was 1.65$/kg-LiOH (US) at 400 A/m2, which is lower than the cost of 1.91$/kg-LiOH (US) for flagship membranes with identical product quality. BMED with an isolation chamber provides a viable solution for acid-base production by balancing product quality and cost.

Membranes with precise ion transport behaviors are regarded as an alternative for lithium (Li) extraction from water streams. Current membranes demonstrate limited viability due to the lack of efficient Li + -selective architectures. We propose an electric field–assisted ion control hypothesis in reinforcing ultraefficient Li + -selective membranes, in which an ionized zeolitic imidazolate framework layer (Q-PEI@ZIF) is constructed via polyethylenimine (PEI) in situ confinement conversion and subsequent quaternization of 2,3-epoxypropyl trimethyl ammonium chloride. In electrodialysis at 5 milliampere per square centimeter, the resulting membrane Q(5%)-PEI(1.0)@ZIF#CEM shows that the ion permeation rates follow the order of K + ~ Li + > Na + > Ca 2+ ~ Mg 2+ , corresponding to 0.31, 0.30, 0.25, 0, and 0 mole per square meter per hour in 120 minutes, respectively. With a 25-millimolar Li + /Mg 2+ mixed solution, it exhibits an unprecedented Li + /Mg 2+ permselectivity of 20,000 and 99.99% purity of Li + product in 120 minutes. This study expands the hypothesis of electric field–assisted ion control in enabling an ultraefficient Li + -selective construction.

Rotor cooling water is a pivotal element for the safe operation of a synchronous condenser in an ultrahigh-voltage grid. To decrease the dissolved oxygen and carbon dioxide contents, tremendous efforts have been dedicated to regulating the solution pH and conductivity. The traditional chemical pH adjustment and resin regeneration methods for rotor cooling water alkalization have the disadvantages of high chemical consumption and high operation and maintenance costs. Here, we propose an electrochemical method for alkalizing the rotor cooling water of a synchronous condenser by taking advantage of the accelerating water dissociation feature in bipolar membranes. The experiments with carbon dioxide injected deionized water revealed that water dissociation in bipolar membrane is capable of increasing the solution pH from 4.6 to 5.6 and decreasing the conductivity from 9.5 μS/cm to less than 2.0 μS/cm. It is convenient to increase the solution pH from 6.5 to even 10.0 when real rotor cooling water is used. BP-A-BP is more competitive than BP-C-A-BP for alkalization purposes. The present study also provides a cost-effective and chemical-free technique to precisely control the water quality of the rotor cooling water in a synchronous condenser.

Triggering the lattice oxygen mechanism is an attractive tactic to overcome the sluggish oxygen evolution reaction (OER) kinetics but suffers from catalytic instability. Here, we report a carbon dots (CDs) mask anchoring strategy to simultaneously improve the activity and stability of nickel-iron layered double hydroxide (NiFe LDH). The synthesized CDs@NiFe LDH resulted in a low overpotential of 193 mV that reached a current density of 10 mA cm-2 and sustained stable alkaline seawater electrocatalysis of over 1000 h at 500 mA cm-2. Spectroscopic and computational studies unravel that the rigid carbon rings and wrench-like amino/carboxyl groups in CDs synergistically tore the surface lattice of NiFe (oxy) hydroxides and altered the local electronic structure, promoting the deprotonation of peroxide intermediate and activating lattice oxygen in the OER. Furthermore, the CDs mask stabilized metal centers and CDs attachment to NiFe LDH surface via Ni/Fe-N coordination selectively repelled chloride and facilitated hydroxide/water transportation. This work proposes a fresh route to break the activity-stability trade-off in nonprecious OER catalysts for seawater electrolysis.

A burgeoning hydrogen technology utilizing anion exchange membranes (AEMs) has attracted increasing interest owing to its potential for cost-effective commercial values. Nonetheless, there are still challenges pertaining to conductivity and persistent stability. Herein, an innovative approach has been introduced to enhance the alkaline resistance and conductivity of AEMs via π-π interactions. The synergistic π-stacking networks in the polymer backbone induce long-range cation aggregation through directed self-assembly, generating ionic cluster microdomains. These nanoconfined environments elevate local hydroxide concentration, leading to the increased density of accessible ion hopping sites within the localized regions. Furthermore, the electron-donating effects of pyrene effectively reduce the electrostatic potential of the β-H adjacent to quaternary ammonium cations, thus increasing the energy barrier for OH− nucleophilic attack. The obtained AEMs demonstrate exceptional performance, exhibiting both high conductivity (160 mS/cm) and excellent alkaline stability (merely 0.35

Accurate and real-time state of charge (SOC) monitoring is critical for the safe, efficient, and stable long-term operation of vanadium redox flow batteries (VRFBs). Traditional monitoring methods are susceptible to errors arising from side reactions, cumulative drift, and electrolyte imbalance. This study develops a non-invasive optical sensor module for the negative electrolyte (anolyte), utilizing the favorable spectral properties of V(II)/V(III) ions at 850 nm for real-time SOC tracking. A fifth-order polynomial model was employed for calibration, successfully managing the non-linear optical response of highly concentrated electrolytes and achieving exceptional accuracy (adjusted R2 > 0.9999). The optical sensor reliably tracked capacity degradation over 50 galvanostatic cycles, yielding a degradation curve that showed a high correlation with the conventional coulomb counting method, thus confirming its feasibility for assessing battery’s state of health. Contrary to initial expectations, operating at higher current densities resulted in a lower capacity degradation rate (CDR). This phenomenon is primarily attributed to the time-dependent nature of parasitic side reactions. Higher current densities reduce the cycle duration, thereby minimizing the temporal exposure of active species to degradation mechanisms and mitigating cumulative ion imbalance. This mechanism was corroborated by physicochemical analysis via UV-Vis spectroscopy, which revealed a strong correlation between the severity of spectral deviation and the CDR ranking. This non-invasive optical technology offers a low-cost and effective solution for precise VRFB management and preventative maintenance.

Efficient separation of magnesium and lithium is essential for the extraction of lithium resources from salt-lake brines. However, the current membrane separation technologies are challenged by the membrane permeability-selectivity trade-off. Herein, we demonstrated a facile and practical approach to fabricate crown ether-functionalized polymeric membranes with excellent Li+/Mg2+ separation performance by incorporating 12-crown-4 rings into the cellulose triacetate polymer network. The tightly and regularly arranged polymer chains anchored the crown ether rings firmly in the membrane structure, thereby facilitating the formation of stable and highly selective cation transport channels inside the membrane. As a result, the prepared membrane achieved an ultrahigh Li+/Mg2+ separation factor of similar to 872 and Li+ flux of 22.6 mu mol m(-2) s(-1), which was much superior to that of commercial CIMS and reported membrane separation technologies. The good long-term stability of the fabricated membrane is promising for achieving efficient magnesium-lithium separation in large-scale industrial applications.

This study describes the synthesis of high-performance cauliflower-like NiMoP nanosphere electrocatalysts on a titanium mesh via a scalable pulse electrodeposition technique. The optimized cauliflower-like NiMoP demonstrates remarkable activity for the hydrogen evolution reaction in alkaline seawater, requiring only 50.3 mV overpotential to drive 10 mA cm-2 and exhibiting exceptional durability, with only 0.5% current degradation over 24 hours. This superior performance is attributed to a unique combination of an amorphous structure, a high-surface-area morphology, and synergistic electronic effects among the Ni, Mo, and P components. This work not only presents a top-tier catalyst but also validates pulse electrodeposition as a powerful strategy for engineering catalyst architecture and electronic properties, opening a promising pathway for scalable and efficient hydrogen generation directly from saline environments.

Rapid and highly effective enrichment of nuclides containing liquid effluent is crucial for online monitoring of radioactive trace elements from nuclear power plants (NPPs). In this study, auxiliary electrodialysis (AED) was proposed for high enrichment of trace ions in the liquid effluents of NPPs. The effects of the auxiliary ion type and concentration and the operating voltage on the AED concentration performance were investigated. When the volume ratio of the solution was 140: 1 with 0.03 mol/L HNO3 as the auxiliary electrolyte, most of the nuclide ions were concentrated more than 50 times after the two-stage electrodialysis experiment. In the first-stage electrodialysis, the concentration of most ions, with the exception of the higher valence ions (Ru3+ and Zr4+), tends to increase with increasing operating voltage. The diluate stream volume could be minimized to 98.8% with a total energy consumption of 9.5 kWh/m(3). By considering the impact of boron in the liquid effluents, more than 52 times concentrations could still be achieved by extending the running time of the first-stage ED (increasing the ion removal rate). The transmembrane fluxes of various cations decreased in the order of Cs+ > Sr2+ > Zn2+ > Co2+ approximate to Ni2+ approximate to Mn2+ > Fe3+ > Cr3+ > Ru3+ > Zr4+, which is attributed to the experimental operating parameters and ionic properties. This research provided a viable technique for rapid and highly effective enrichment of nuclides containing liquid effluents for both radioactive element monitoring and wastewater volume reduction.