A Nano-Heterogeneous Membrane for Efficient Separation of Lithium from High Magnesium/Lithium Ratio Brine

Lithium extraction from salt lake brines is highly demanded to circumvent the lithium supply shortage. However, polymer nanofiltration membranes suffer from low lithium permeability while nanofluidic devices are hindered by complicated preparation and miniaturized scales despite high permeability. Here, the authors report a facile strategy to prepare positively charged nanofiltration membranes for ultrapermeable and selective separation of lithium ions from concentrated magnesium/lithium mixtures. A new electrolyte monomer (diaminoethimidazole bromide, DAIB) containing bidentate amine groups is designed to modify pristine polyamide composite membranes. Structure characterizations and simulations show that the DAIB modification brings about nano-heterogeneity that not only improves surface hydrophilicity, but also reduces water transport resistance through the ≈100 nm thick separation layer. Water permeance of the modified membrane improves fivefold and is coupled with good stability in 200-h continuous nanofiltration. It exhibits high lithium flux (0.7 mol m⁻² h⁻¹) for brines (Mg²⁺/Li⁺ ratio 20) at 6 bar operation pressure.     

Fungal Cell Wall-Graphene Oxide Microcomposite Membrane for Organic Solvent Nanofiltration

High permeability and selectivity have long been pursued in membrane separation technology. However, this purpose remains a paramount challenge for molecular separations mainly limited by the trade-off between permeance and -selectivity. Here, a bio-utilization strategy based on deep understanding of bio-features to fabricate a cell wall-graphene oxide microcomposite membrane for organic solvent nanofiltration is rationally designed. The membrane displays a unique configuration with alternating stacking of cell wall layers and ultrathin graphene oxide layers. Moreover, the interactions between the cell wall and graphene oxide as well as between the membrane and solvent are mainly revealed by all atom molecular dynamics to uncover the possible working principle of the membrane. Specifically, the strong graphene oxide-cell wall interaction and anti-swelling behavior of the cell wall together restrict the expansion of the graphene oxide layer to promise high selectivity. Meanwhile, the well-developed porosity of the cell wall allows a high throughput of various solvents through the membrane, showing excellent rejection for small molecules and solvent permeance as high as 56 L m² h¹ bar⁻¹. The proposed cell wall microcomposite 2D structure could encourage the practical applications of GO-based membranes.     

Understanding the Ion Transport Behavior across Nanofluidic Membranes in Response to the Charge Variations

Biological pores regulate the cellular traffic of a diverse collection of molecules, often with extremely high selectivity. Given the ubiquity of charge-based separation in nature, understanding the link between the charged functionalities and the ion transport activities is essential for designing delicate separations, with the correlation being comparatively underdeveloped. Herein, the effect of charge density from the impact of pore structure is decoupled using a multivariate strategy for the construction of covalent organic framework-based membranes. How the density of charged sites in the nanofluidic membranes affect the ion transport activity with particular emphasis on Li⁺ and Mg²⁺ ions, relevant to the challenge of salt-lake lithium mining is systematically investigated. Systematic control of the charge distribution produces membranes with numerous advantages, overcoming the long-term challenge of Li⁺/Mg²⁺ separation. The top membrane exhibits an outstanding equilibrium selectivity for Li⁺ over Mg²⁺ and operational stability under diffusion dialysis and electrodialysis conditions (Li⁺/Mg²⁺ up to 500), qualifying it as a potential candidate for lithium extraction. It is anticipated that the developed nanofluidic membrane platform can be further leveraged to tackle other challenges in controlled separation processes.     

Controlling the Selectivity of Conjugated Microporous Polymer Membrane for Efficient Organic Solvent Nanofiltration

To realize selective separation of important small molecules in organic solvents with high permeability is highly desired but not attained yet, because it requires stringent control over selectivity in nanofiltration membranes. Here, a thiophene‐containing conjugated microporous polymer membrane, in which the pore size is finely tuned at the angstrom scale through postoxidation of the thiophene moieties, is reported. The successful modification is confirmed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and water contact angle, leading to obvious pore size reduction evidenced by nitrogen adsorption. Upon postmodification, the selectivity of the membrane can be effectively controlled. In the pristine membrane, the methanol permeance reaches 32 liters per square meter per hour per bar (L m^?2 h^?1 bar^?1) with a molecular weight cut‐off (MWCO) of 800 g mol^?1. Significantly, after in situ postmodification of thiophene moieties, the largest pore size is reduced from 1.73 to 1.48 nm, giving rise to a remarkable decrease of MWCO from 800 to 500 g mol^?1, while the permeance of methanol still maintains as high as 21 L m^?2 h^?1 bar^?1.     

Pore Tuning of Metal-Organic Framework Membrane Anchored on Graphene-Oxide Nanoribbon

Although the pore structures and gas transport properties of metal-organic frameworks (MOFs) have been tuned mainly by modifying the framework building blocks, a pore-tuned zeolitic imidazolate framework (ZIF)-8 layer is directly grown on graphene oxide nanoribbons (GONR)-treated polymer substrate. Oxygen-containing functional groups and GONR dangling-carbon bonds facilitated the spontaneous growth of ZIF-8 oriented to the (100) grain on the GONR surface and also enhanced the rigidity by strongly anchoring the ZIF-8 layer by metal-carbon chemisorption. Gas permeation and molecular simulation results confirmed that the effective aperture size of ZIF-8 is adjusted to 3.6 Å. As a result, ultrafast H₂ permeance of 7.6 × 10⁻⁷ mol m⁻² Pa s is achieved while blocking large hydrocarbon molecules. In particular, the membrane showed exceptionally enhanced hydrogen selectivity for the mixture separation than ideal selectivity, owing to the competitive transport between H₂ and large hydrocarbon molecules, and the separation performance surpassed those of ZIF membranes previously fabricated on polymeric supports.     

Polyamide Nanofilms through a Non-Isothermal-Controlled Interfacial Polymerization

Efficient thin film composite polyamide (PA) membranes require optimization of interfacial polymerization (IP) process. However, it is challengeable owing to its ultrafast reaction rate coupled with mass and heat transfer, yielding heterogeneous PA membranes with low performance. Herein, a non-isothermal-controlled IP (NIIP) method is proposed to fabricate a highly permeable and selective PA membrane by engineering IP at the cryogenic aqueous phase (CAP) to achieve synchronous control of heat and mass transfer in the interfacial region. The CAP also enables the phase transition of the aqueous solution from the liquid to solid state, providing a more comprehensive understanding of the fundamental mechanisms involved in different phase states in the IP process. Consequently, the PA membrane exhibits excellent separation performance with ultrahigh water permeance (42.9 L m⁻² h⁻¹ bar⁻¹) and antibiotic desalination efficiency (antibiotic/NaCl selectivity of 159.3). This study provides new insights for the in-depth understanding of the precise mechanism linking IP to the performance of the targeting membrane.     

Heterogeneous MXene/PS-b-P2VP Nanofluidic Membranes with Controllable Ion Transport for Osmotic Energy Conversion

Membrane-based osmotic power harvesting is a strategy for sustainable power generation. 2D nanofluids with high ion conductivity and selectivity are emerging candidates for osmotic energy conversion. However, the ion diffusion under nanoconfinement is hindered by homogeneous 2D membranes with monotonic charge regulation and severe concentration polarization, which results in an undesirable power conversion performance. Here, an asymmetric nanochannel membrane with a two-layered structure is reported, in which the angstrom-scale channels of 2D transition metal carbides/nitrides (MXenes) act as a screening layer for controlling ion transport, and the nanoscale pores of the block copolymer (BCP) are the pH-responsive arrays with an ordered nanovoid structure. The heterogeneous nanofluidic device exhibits an asymmetric charge distribution and enlarged 1D BCP porosity under acidic and alkaline conditions, respectively; this improves the gradient-driven ion diffusion, allowing a high-performance osmotic energy conversion with a power density of up to 6.74 W m⁻² by mixing artificial river water and seawater. Experiments and theoretical simulations indicate that the tunable asymmetric heterostructure contributes to impairing the concentration polarization and enhancing the ion flux. This efficient osmotic energy generator can advance the fundamental understanding of the MXene-based heterogeneous nanofluidic devices as a paradigm for membrane-based energy conversion technologies.     

Cation Exchange Membranes with Bi-Functional Sites Induced Synergistic Hydrophilic Networks for Selective Proton Transport

Acid recycling via cation exchange membranes (CEMs) has attracted considerable attention from traditional industries and advanced manufacturing because of the economic and environmental advantages. However, current polymeric CEMs merely have constant ion channels by the fixed groups in the matrix and lack the synergy of bi-functional sites. Herein, a series of dibenzo-18-crown-6 (DB18C6) functionalized sulfonated poly(biphenyl alkylene) membranes is reported. The resultant membranes form phase separation and ordered ion channels by the electrostatic interaction between DB18C6-H⁺ complexes and the  SO₃⁻ anionic sites, constructing a low-swelling synergistic hydrophilic network. The prepared membranes have high proton permeation rates of 2.98-4.85 mol m⁻² h^-1 and extremely low ferrous ion permeabilities, leading to a high H⁺/Fe²⁺ selectivity of ≈3153 at the current density of 10 mA cm^-2, which is one order of magnitude higher than the commercial and previously reported membranes via the electrodialysis. These results provide strategies for designing bi-functional ion exchange membranes for selective ion transport via utilizing crown ether/cation complexes.     

Ultrathin Polymer Films with Intrinsic Microporosity: Anomalous Solvent Permeation and High Flux Membranes

Organic solvent nanofiltration (OSN) membranes with ultrathin separation layers down to 35 nm in thickness fabricated from a polymer of intrinsic microporosity (PIM‐1) are presented. These membranes exhibit exceptionally fast permeation of n‐heptane with a rejection for hexaphenylbenzene of about 90%. A 35 nm thick PIM‐1 membrane possesses a Young's modulus of 222 MPa, and shows excellent stability under hydraulic pressures of up to 15 bar in OSN. A maximum permeance for n‐heptane of 18 Lm^?2h^?1bar^?1 is achieved with a 140 nm thick membrane, which is about two orders of magnitude higher than Starmem240 (a commercial polyimide‐based OSN membrane). Unexpectedly, decreasing the film thickness below 140 nm results in an anomalous decrease in permeance, which appears to be related to a packing enhancement of PIM‐1, as measured by light interferometry. Further, thermal annealing of the membranes formed from PIM‐1 reveals that their permeance is preserved up to temperatures in excess of 150 °C, whereas the permeance of conventional, integrally skinned, asymmetric polyimide OSN membranes decreases significantly when they are annealed under the same conditions. To rationalize this key difference in response of functional performance to annealing, the concept of membranes with intrinsic microporosity (MIMs) versus membranes with extrinsic microporosity (MEMs) is introduced.     

Battery Electrode Materials with Omnivalent Cation Storage for Fast and Charge‐Efficient Ion Removal of Asymmetric Capacitive Deionization

Capacitive deionization (CDI) that engages porous carbon electrodes constitutes one of the well‐established energy‐efficient desalination methods. However, improvement in desalination performance, including ion removal capacity, ion removal rate, and charge efficiency remains requisite for a wide range of applications. Herein, an ion‐exchange membrane‐free asymmetric CDI is introduced by pairing a metal organic framework (MOF), namely, K_0.03Cu[Fe(CN)₆]_0.65·0.43H₂O and porous carbon. The exclusive intercalation of cations into the MOF prevents the reverse adsorption of co‐ions (anions), thus significantly improving ion removal capacity (23.2 mg g^?1) and charge efficiency (75.8%). Moreover, by utilizing the advantage of the MOF that diverse mono‐ and divalent cations can be stored in the narrow redox potential range, the asymmetric CDI allows simultaneous capture of mono‐ and divalent cations, thus achieving omnivalent cation removal. Moreover, cations are intercalated in the hydrated forms without a discrete phase transition of the host structure, facilitating rapid desalination by reducing the desolvation energy penalty, which results in a high ion removal rate of 0.24 mg g^?1 s^?1. This study offers a new design principle in CDI: the integration of a crystal structure with large ionic channels that enable hydrated intercalation of multivalent ions in a fast and exclusive manner.     

Aqueously Cathodic Deposition of ZIF‐8 Membranes for Superior Propylene/Propane Separation

Electrochemical deposition has emerged as a novel approach to fabricate metal–organic framework (MOF) films. Here, for the first time, an aqueously cathodic deposition (ACD) approach is developed to fabricate ZIF‐8 type of MOF membranes without addition of any supporting electrolyte or modulator. The fabrication process uses 100% water as the sole solvent and a low‐defect density membrane is obtained in only 60 min under room temperature without any pre‐synthesis treatment. The membrane exhibits superior performance in C₃H₆/C₃H₈ separation with 182 GPU C₃H₆ permeance and 142 selectivity, making it sit at the upper bound of permeance versus selectivity graph, outperforming majority of the published data up to 2019. Notably, this approach uses an extremely low current density (0.13 mA cm^?2) operated under an ultrafacile apparatus set‐up, enabling an attractive way for environmentally friendly, energy efficient, and easily scalable MOF membrane fabrications. This work demonstrates a great potential of aqueously electrochemical deposition of MOF membrane in the future research.     

Nano-confined Supramolecular Assembly of Ultrathin Crystalline Polymer Membranes for High-Performance Nanofiltration

Polymer membranes with high permeability, high salt rejection, and mechanical integrity are desirable in water treatment and purification. However, it remains a daunting challenge to achieve ultrathin yet robust polymer membranes harvesting all the above features for nanofiltration. Here, a new approach of nano-confined supramolecular assembly to fabricate ultrathin crystalline polymer membranes with a modulus of 1 GPa and a thickness of 6.5 nm is reported. The microdroplet carrying amphiphilic tetra-oligomers can quickly spread at the air–-water interface, where the hydrophilic motifs such as carbonyl and hydroxyl groups can reconfigurably anchor down to water molecules via abundant hydrogen bonding interactions, significantly promoting the alignment and orientation of hydrophobic alkyl chains within the nano-confined space. The resultant nano-films exhibit mechanical robustness as well as excellent ion sieving with improved NaCl rejection of 81.3% and unprecedented Na₂SO₄ rejection of 99.9% without compromising water permeation, outperforming the reported and commercial state-of-the-art polymer membranes. This work enables the rapid production of over 100 cm² ultrathin crystalline polymer membranes with great nanofiltration potential and highlights the critical role of supramolecular assembly in the chemical and structural configurations in a nano-confined space.     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

Metal Soap Membranes for Gas Separation

Metal soaps or metal alkanoates are metal–organic complexes held together with metal cations and the functional groups of hydrocarbon chains. They can be synthesized at a high yield by simply mixing the metal and organic sources, forming crystalline frameworks with diverse topology, and have been studied in the past because of their rich polymorphism-like liquid crystals. Their ability to melt while retaining the crystalline properties upon cooling is unique among nanoporous materials and is especially attractive for membrane fabrication. Herein, metal soaps as a new class of material for molecular separation are reported. Three metal soaps, Ca(SO₄C₁₂H₂₅)₂, Zn(COOC₆H₁₃)₂, and Cu(COOC₉H₁₉)₂, hosting lamellar structure with molecular-sized channels are synthesized. They are processed in thin, intergrown, polycrystalline films on porous substrates by two scalable methods, interfacial crystallization and melting with an extremely small processing time (a minute to an hour). The resulting crystalline films are oriented with the alkyl chains perpendicular to the porous substrate which favors molecular transport. The prepared membranes demonstrate attractive gas separation behavior, e.g., 300-nm-thick Ca(SO₄C₁₂H₂₅)₂ membrane prepared in a minute using interfacial crystallization yields H₂ permeance of 6.1 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ with H₂/CO₂ selectivity of 10.5.     

Ultrathin 2D‐Layered Cyclodextrin Membranes for High‐ Performance Organic Solvent Nanofiltration

Synthetic membranes with a high selectivity for demanding molecular separations and high permeance have a large potential for the reduction of energy consumption in separation processes. Herein, for the first time, the fabrication of an ultrathin layered macrocycle membrane for molecular separation in organic solvent nanofiltration using per‐6‐amino‐β‐cyclodextrin as a monomer for membrane manufacturing by interfacial polymerization is reported. Compared to a regular nonfunctionalized cyclodextrin, a higher reactivity is observed, enabling a very fast membrane formation under mild conditions. The formed membrane is composed of a layered structure of polymerized cyclodextrin, which shows high stability in different organic solvents. The membrane exhibits excellent separation performance for organic solvent nanofiltration, both with nonpolar and polar solvents. Most importantly, this new membrane type can discriminate between molecules with nearly identical molecular weights but different shapes. The unmatched high permeance and shape selectivity of the membranes can be attributed to the ultralow thickness, controlled microporosity, as well as the layered macrocycle structure, which makes the membranes promising for high‐performance molecular separation in the chemical and biochemistry industry.     

High‐Performance CO2 Capture through Polymer‐Based Ultrathin Membranes

Thin film composite (TFC) membranes have attracted great research interest for a wide range of separation processes owing to their potential to achieve excellent permeance. However, it still remains challenging to fully exploit the superiority of thin selective layers when mitigating the pore intrusion phenomenon. Herein, a facile and generic interface‐decoration‐layer strategy collaborating with molecular‐scale organic–inorganic hybridization in the selective layer to obtain a high‐performance ultrathin film composite (UTFC) membrane for CO₂ capture is reported. The interface‐decoration layer of copper hydroxide nanofibers (CHNs) enables the formation of an ultrathin selective layer (≈100 nm), achieving a 2.5‐fold increase in gas permeance. The organic part in the molecular‐scale hybrid material contributes to facilitating CO₂‐selective adsorption while the inorganic part assists in maintaining robust membrane structure, thus remarkably improving the selectivity toward CO₂. As a result, the as‐prepared membrane shows a high CO₂ permeance of 2860 GPU, superior to state‐of‐the‐art polymer membranes, with a CO₂/N₂ selectivity of 28.2. The synergistic strategy proposed here can be extended to a wide range of polymers, holding great potential to produce high‐efficiency ultrathin membranes for molecular separation.     

Alternative-Ultrathin Assembling of Exfoliated Manganese Dioxide and Nitrogen-Doped Carbon Layers for High-Mass-Loading Supercapacitors with Outstanding Capacitance and Impressive Rate Capability

Manganese dioxide (MnO₂) materials have received much attention as promising pseudocapacitive materials owing to their high theoretical capacitance and natural abundance. Unfortunately, the charge storage performance of MnO₂ is usually limited to commercially available mass loading electrodes because of the significantly lower electron and ion migration kinetics in thick electrodes. Here, an alternatively assembled 2D layered material consisting of exfoliated MnO₂ nanosheets and nitrogen-doped carbon layers for ultrahigh-mass-loading supercapacitors without sacrificing energy storage performance is reported. Layered birnessite-type MnO₂ is efficiently exfoliated and intercalated by a carbon precursor of dopamine using a fluid dynamic-induced process, resulting in MnO₂/nitrogen-doped carbon (MnO₂/C) materials after self-polymerization and carbonization. The alternatively stacked and interlayer-expanded structure of MnO₂/C enables fast and efficient electron and ion transfer in a thick electrode. The resulting MnO₂/C electrode shows outstanding electrochemical performance at an ultrahigh mass loading of 19.7 mg cm⁻², high gravimetric and areal capacitances of 480.3 F g⁻¹ and 9.4 F cm⁻² at 0.5 mA cm⁻², and rapid charge/discharge capability of 70% capacitance retention at 40 mA cm⁻². Furthermore, asymmetric supercapacitor based on high-mass-loading MnO₂/C can deliver an extremely high energy of 64.2 Wh kg⁻¹ at a power density of 18.8 W kg⁻¹ in an aqueous electrolyte.     

Electrophoretic Nuclei Assembly for Crystallization of High‐Performance Membranes on Unmodified Supports

Metal–organic framework (MOF) films have recently emerged as highly permselective membranes yielding orders of magnitude higher gas permeance than that from the conventional membranes. However, synthesis of highly intergrown, ultrathin MOF films on porous supports without complex support‐modification has proven to be a challenge. Moreover, there is an urgent need of a generic crystallization route capable of synthesizing a wide range of MOF structures in an intergrown, thin‐film morphology. Herein, a novel electrophoretic nuclei assembly for crystallization of highly intergrown thin‐films (ENACT) approach, that allows synthesis of ultrathin, defect‐free ZIF‐8 on a wide range of unmodified supports (porous polyacrylonitrile, anodized aluminum oxide, metal foil, porous carbon and graphene), is reported. As a result, a remarkably high H₂ permeance of 8.3 × 10^?6 mol m^?2 s^?1 Pa^?1 and ideal gas selectivities of 7.3, 15.5, 16.2, and 2655 for H₂/CO₂, H₂/N₂, H₂/CH₄, and H₂/C₃H₈, respectively, are achieved from an ultrathin (500 nm thick) ZIF‐8 membrane. A high C₃H₆ permeance of 9.9 × 10^?8 mol m^?2 s^?1 Pa^?1 and an attractive C₃H₆/C₃H₈ selectivity of 31.6 are obtained. The ENACT approach is straightforward, reproducible and can be extended to a wide range of nanoporous crystals, and its application in the fabrication of intergrown ZIF‐7 films is demonstrated.     

Ultrathin Graphene Nanofiltration Membrane for Water Purification

A method of fabricating ultrathin (≈22–53 nm thick) graphene nanofiltration membranes (uGNMs) on microporous substrates is presented for efficient water purification using chemically converted graphene (CCG). The prepared uGNMs show well packed layer structure formed by CCG sheets, as characterized by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The performance of the uGNMs for water treatment was evaluated on a dead end filtration device and the pure water flux of uGNMs was high (21.8 L m^?2 h^?1 bar^?1). The uGNMs show high retention (>99%) for organic dyes and moderate retention (≈20–60%) for ion salts. The rejection mechanism of this kind of negatively charged membranes is intensively studied, and the results reveal that physical sieving and electrostatic interaction dominate the rejection process. Because of the ultrathin nature of uGNMs, 34 mg of CCG is sufficient for making a square meter of nanofiltration membrane, indicating that this new generation graphene‐based nanofiltration technology would be resource saving and cost‐effective. The integration of high performance, low cost, and simple solution‐based fabrication process promises uGNMs great potential application in practical water purification.     

Divalent Ion Selectivity in Capacitive Deionization with Vanadium Hexacyanoferrate: Experiments and Quantum-Chemical Computations

Selective removal of ions from water via capacitive deionization (CDI) is relevant for environmental and industrial applications like water purification, softening, and resource recovery. Prussian blue analogs (PBAs) are proposed as an electrode material for selectively removing cations from water, based on their size. So far, PBAs used in CDI are selective toward monovalent ions. Here, vanadium hexacyanoferrate (VHCF), a PBA, is introduced as a new electrode material in a hybrid CDI setup to selectively remove divalent cations from water. These electrodes prefer divalent Ca²⁺ over monovalent Na⁺, with a separation factor, β_Ca/Na ≈3.5. This finding contrasts with the observed monovalent ion selectivity by PBA electrodes. This opposite behavior is understood by density functional theory simulations. Furthermore, coating the VHCF electrodes with a conducting polymer (poly-pyrrole, doped with poly-styrenesulphonate) prevents the contamination of the treated water following the degradation of the electrode. This facile and modular coating method can be effortlessly extended to other PBA electrodes, limiting the extent of treated water contamination during repeated cycling. This study paves the way for tunable selectivity while extending the library of electrodes that can be successfully used in (selective) CDI.