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Owing to its 100% theoretical salt rejection capability, membrane distillation (MD) has emerged as a promising seawater desalination approach to address freshwater scarcity. Ideal MD requires high vapor permeate flux established by cross-membrane temperature gradient (∆T) and excellent membrane durability. However, it’s difficult to maintain constant ∆T owing to inherent heat loss at feedwater side resulting from continuous water-to-vapor transition and prevent wetting transition-induced membrane fouling and scaling. Here, we develop a Ti 3 C 2 T x MXene-engineered membrane that imparts efficient localized photothermal effect and strong water-repellency, achieving significant boost in freshwater production rate and stability. In addition to photothermal effect that circumvents heat loss, high electrically conductive Ti 3 C 2 T x MXene also allows for self-assembly of uniform hierarchical polymeric nanospheres on its surface via electrostatic spraying, transforming intrinsic hydrophilicity into superhydrophobicity. This interfacial engineering renders energy-efficient and hypersaline-stable photothermal membrane distillation with a high water production rate under one sun irradiation. Membrane distillation is susceptible to thermal inefficiency and membrane wetting issues during seawater desalination. Here, authors design a MXene-engineered membrane that imparts efficient localized photothermal effect and strong water repellency, achieving sustainable freshwater production.

Mineral crystal formation poses a challenge on surfaces (e.g., heat exchangers, pipes, membranes, etc.) in contact with super-saturated fluids. Applying alternating currents (AC) to such surfaces can prevent surface crystallization under certain conditions. Here, we demonstrate that ion displacement induced by periodic charging and discharging of the electrical double layer (EDL) inhibits both heterogeneous and homogeneous nucleation (and crystal growth) of CaCO 3 . Titanium sheets (meant to simulate metallic heat exchanger surfaces) are immersed in super-saturated CaCO 3 solutions with a saturation index >11. We show that at relatively high AC frequencies, incomplete EDL formation leads to an alternating electric field that propagates far into the bulk solution, inducing rapid ion migration that overwhelms the Brownian motion of ions. Electrochemical characterization reveals EDL charging/discharging under AC conditions that greatly inhibits precipitation. Operating at 4 V pp , 0.1–10 Hz reduces turbidity by over 96% and reduces CaCO 3 coverage on the metal plates by over 92%. Based on electrokinetic and crystallization models, the ion displacement velocity (exceeding the mean Brownian velocity) and displacement length disrupts ion collision and crystal nucleation. Overall, the technique has potential for preventing mineral crystal formation in heat exchangers and many other industrially relevant systems. Nucleation and growth of mineral crystals plague surfaces in contact with supersaturated fluids such as heat exchangers. Here, authors achieve near complete ( > 92%) mitigation of CaCO3 precipitation via alternating electric field and elucidate the mechanism through ion displacement and EDL charging.

Recent advancements in membrane-assisted seawater electrolysis powered by renewable energy offer a sustainable path to green hydrogen production. However, its large-scale implementation faces challenges due to slow power-to-hydrogen (P2H) conversion rates. Here we report a modular forward osmosis-water splitting (FOWS) system that integrates a thin-film composite FO membrane for water extraction with alkaline water electrolysis (AWE), denoted as FOWS AWE . This system generates high-purity hydrogen directly from wastewater at a rate of 448 Nm 3  day −1  m − 2 of membrane area, over 14 times faster than the state-of-the-art practice, with specific energy consumption as low as 3.96 kWh Nm −3 . The rapid hydrogen production rate results from the utilisation of 1 M potassium hydroxide as a draw solution to extract water from wastewater, and as the electrolyte of AWE to split water and produce hydrogen. The current system enables this through the use of a potassium hydroxide-tolerant and hydrophilic FO membrane. The established water-hydrogen balance model can be applied to design modular FO and AWE units to meet demands at various scales, from households to cities, and from different water sources. The FOWS AWE system is a sustainable and an economical approach for producing hydrogen at a record-high rate directly from wastewater, marking a significant leap in P2H practice. Green hydrogen production faces increased water risks due to scarce supplies of water. Here, authors develop a modular forward osmosis-water splitting system that utilises wastewater effluent to generate high-purity hydrogen, providing a sustainable solution for water and energy security.

To ascertain membrane distillation (MD) as an emerging desalination technology to meet the global water challenge, development of membranes with ideal material properties is crucial. Functionalized carbon nanotubes (CNTs) were anchored to nanofibres of electrospun membranes. Covalent modification and fluorination of CNTs improved their dispersibility and interfacial interaction with the polymer membrane, resulting in well-aligned CNTs inside crystalline fibres with superhydrophobicity. Consideration for the chemical/physical properties of the CNT composite membranes and calculation of their theoretical fluxes revealed the mechanism of MD: CNTs facilitated the repulsive force for Knudsen and molecular diffusions, reduced the boundary-layer effect in viscous flow, and assisted surface diffusion, allowing for fast vapor transport with anti-wetting. This study shows that the role of CNTs and an optimal composite ratio can be used to reduce the gap between theoretical and experimental approaches to desalination.

Omniphobic membranes, due to their exceptional properties, have drawn significant attention for overcoming the bottleneck in membrane distillation (MD) technology. This study demonstrates an innovative method for fabricating an omniphobic membrane that is simple and facile compared to other methods such as wet/dry etching and photolithography. The surface morphology of springtails was imitated using electrospraying technique to coat a polyvinylidene fluoride substrate with concave-shaped polystyrene beads that were successfully developed by controlling the electrical traction (voltage) and air resistance (humidity). Then, the lipid coating of springtail surfaces was mimicked by dip-coating the membrane in a low-toxicity short-chain perfluoropolyether lubricant. The concave structure’s tiny air pockets increased membrane hydrophobicity significantly, indicated by the fact that the first round of water bouncing took only 16.3 ms. Finally, in MD treatment of seawater containing 1.0 mM sodium dodecyl sulfate, the optimized omniphobic membrane maintained a stable 99.9% salt rejection rate. Here, authors successfully fabricated a springtail-inspired nano-concave reentrant structured polystyrene (PS) membrane using electrospraying technology followed by lubricant dip-coating, which endowed the membrane with omniphobic properties.

Sub-10 µm microplastics (MPs) in aquatic environments pose significant ecological and health risks due to their mobility and potential to carry harmful microcontaminants. Our effluent analysis from a Hong Kong Sewage Treatment Works shows that traditional treatment often fails to effectively remove these MPs. These small-sized MPs are commonly neglected due to challenges in accurate quantification, analysis, and removal. This study introduces a nanobubble-assisted flotation process that enhances the removal efficiency of both regular and irregular small-sized MPs from wastewater. The proposed process outperforms the traditional flotation process by fostering a more effective interaction between bubbles and MPs, increasing removal rates of MPs from 1 µm to 10 µm by up to 12% and providing a total efficiency boost of up to 17% for various particle sizes. Improvements are attributed to enhanced collision and adhesion probabilities, hydrophobic interactions, as well as better floc flotation. Supported by empirical evidence, mathematical models, and Molecular Dynamics simulations, this research elucidates the nanoscale mechanisms at play. The findings confirm the nanobubble-assisted flotation technique as an innovative and practical approach to removing sub-10 µm MPs in water treatment processes. Sub-10 µm microplastic pose severe environmental risks. Here, authors introduce an advanced nanobubble assisted flotation technique that enhances microplastic removal, providing a promising solution for effective water treatment.

Thin-film composite membranes are integral to the reverse osmosis (RO) process, effectively converting seawater and brackish water into potable water. While significant strides have been made in improving water permeability and salt rejection, there has been a corresponding lag in enhancing chlorine resistance and boron rejection. This study presents a suprasmolecular nanocrystalline membrane (SNM) with abundant subnanometer channels created through precisely assembled and well-oriented tetra-oligomer chains, enhanced by interfacial hydrogen bonding under nanoconfined space. The 6 nm-thick SNM exhibits highly aligned nanocrystalline domains and a Young’s modulus of 4 ± 0.5 GPa. Benefiting from its ultrathin thickness and well-oriented subnanoscale channels, the SNM functions effectively as a permeation and selective layer, achieving 99.6% NaCl rejection at 55 bar with a 3.5 wt% NaCl feed and delivering 2-4 times higher water permeance than commercial seawater RO membranes. Molecular dynamics simulations reveal that the abundant, well-aligned subnanochannels facilitate rapid water transport while raising the energy barrier for sodium ion transport. Furthermore, the SNM shows superior boron rejection (exceeding 92.5% at pH 7), remarkable chlorine resistance (200 ppm NaClO exposure for 300 hours), and sustained operational stability under extreme pH conditions (1 and 13) for over 168 hours. These findings establish that space-confined interfacial hydrogen bonding governs the precision self-assembly of robust subnanochannels, offering a new paradigm for high-resilience desalination membranes. Thin-film composite membranes for reverse osmosis process are effective converting seawater and brackish water into potable water but usually they are not resistant to chlorine and the boron rejection is poor. Here, the authors show a supramolecular nanocrystalline membrane with ultrathin thickness and well-oriented sub-nano-sized channels to allow for high water permeance, sodium chloride and boron rejection as well as chlorine resistance.

Innovations in self-assembly and aggregate engineering have led to membranes that better balance water permeability with salt rejection, overcoming traditional trade-offs. Here we demonstrate a strategy that uses multivalent H-bond interactions at the nano-confined space to manipulate controllable and organized crystallization. Specifically, we design amphiphilic oligomers featuring hydrophobic segments with strongly polar end-capped motifs. When spreading on air/water interfaces, the hydrophobic parts repel water, yielding an ordered alignment of supramolecular oligomers under nano-confinement, while the strongly polar sections engage in strong hydrogen bonding and reconfigure to strongly interact with water molecules, enabling the controlled assembly and orientation of nano-confined crystalline domains. This arrangement provides dual benefits: refining the distribution of pore sizes for ultra-selectivity and boosting the free volume for water permeation. Compared to counterpart oligomers with weakly polar motifs, the optimized membrane with a 6-nm thickness demonstrates the water permeability of 14.8 L m −2 h −1 bar −1 and extraordinary water/NaCl selectivity of more than 54 bar −1 under pressure-driven condition. This study sheds light on how nano-confined self-assembly and aggregate engineering affect the architectures, functionality, and performance of polymer membranes, emphasizing the promise of controllable crystallization in ultrathin membranes for optimal desalination. Membranes with a balance between water permeability and salt rejection are desirable, and can be developed through self-assembly and aggregation. Here, the authors report a hydrogen-bonding strategy in a nanoconfined space to give controlled crystallisation, for membranes for reverse osmosis.

Separation membranes with inherent low-carbon properties are crucial for energy‒water sustainability but suffer from fouling issue and performance deficiency. Herein, a lotus-leaf-mimetic catalytic membrane is synthesized via 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP)-Co metal-organic intermediate layer-mediated MnO₂ mineralization, transforming hydrophobic polymeric membranes into unique self-cleaning membranes. The derivative abundant oxygen vacancies during hetero-phase mineralization boost their catalytic capability. The lotus leaf-mimicking nano/micro-water pockets at the interface enable the membrane operando flux recovery to reach 99.9%. Most interestingly, the membrane exhibited 24.8-fold greater antifouling ability and 10.6-fold greater recovery compared with the unmineralized membrane, significantly outperforming state-of-the-art membranes. The exceptional performance for water treatment is attributed to active catalytic antifouling coupled with hierarchical antifouling barriers. The computational simulations reveal electron-rich bell-like structures with electron-deficient metal cores. This work paves a way for the fabrication of biomimetic materials for efficient water treatment and beyond. This study reported a lotus-leaf-inspired surface engineering to fabricate a superhydrophilic self-cleaning catalytic membrane via hexahydroxytriphenylene-Co metal-organic framework/film-mediated hierarchical raspberry-like MnO₂ mineralization.

Anion exchange membrane water electrolysis (AEMWE) has seen rapid advancements over the past decade due to its promising role in green hydrogen production. Ensuring long-term functionality is as crucial as optimizing performance to achieve commercial viability and industrial integration. However, few studies have systematically discussed the degradation issues of this technology. Therefore, a thorough understanding of AEMWE degradation is needed to guide the design, assembly, operation, and maintenance of the device over its lifetime. To address this gap, this review systematically overviewed the heterogeneous degradation of AEMWE across different material and interface levels, focusing on several key components including catalysts, ionomers, membranes, and gas diffusion layers. The influences of these components and their interfaces on the catalytic efficiency, active site density, and mass and electron transfer capabilities were discussed. Moreover, the impacts of operation conditions, including temperature, electrolyte composition, and clamping pressure, on the stable operation of AEMWE were assessed. Accordingly, current mitigation strategies to resolve these degradation phenomena were rigorously evaluated. By offering insights into optimizing operations, designing materials, and improving assessment protocols for AEMWE, this work will contribute to enhancing its stability for large-scale hydrogen production.