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The lack of high-performance and substantial supply of anion-exchange membranes is a major obstacle to future deployment of relevant electrochemical energy devices. Here, we select two isomers (m-terphenyl and p-terphenyl) and balance their ratio to prepare anion-exchange membranes with well-connected and uniformly-distributed ultramicropores based on robust chemical structures. The anion-exchange membranes display high ion-conducting, excellent barrier properties, and stability exceeding 8000 h at 80 °C in alkali. The assembled anion-exchange membranes present a desirable combination of performance and durability in several electrochemical energy storage devices: neutral aqueous organic redox flow batteries (energy efficiency of 77.2% at 100 mA cm −2 , with negligible permeation of redox-active molecules over 1100 h), water electrolysis (current density of 5.4 A cm −2 at 1.8 V, 90 °C, with durability over 3000 h), and fuel cells (power density of 1.61 W cm −2 under a catalyst loading of 0.2 mg cm −2 , with open-circuit voltage durability test over 1000 h). As a demonstration of upscaled production, the anion-exchange membranes achieve roll-to-roll manufacturing with a width greater than 1000 mm. The design of highly selective yet robust anion exchange membranes remains a challenge. Here, the authors prepare a stable polymer membrane composed of terphenyl isomers, demonstrate roll-to-roll manufacturing, and assess its properties in redox flow batteries, water electrolyzers and fuel cells.

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives are typical catholytes in aqueous organic redox flow batteries (AORFBs), but reported lifetime of them is limited. We find that the increase of Hirshfeld charge decreases the Gibbs free energy change ( ΔG ) values of side reactions of TEMPO, a near-linear relationship, and then exacerbates their degradation. Here we predict and synthesize a TEMPO derivative, namely TPP-TEMPO, by analyzing the Hirshfeld charge. TPP-TEMPO, with the smallest Hirshfeld charge and highest ΔG , is an order of magnitude more stable than TMA-TEMPO (N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride, a control with the largest Hirshfeld charge and lowest ΔG ). We further elaborate on their decomposition pathways, identify byproducts, and mitigate degradation by supporting electrolyte engineering. Finally, a TPP-TEMPO/BTMAP-Vi (1,1′-bis[3-(trimethylammonio)propyl]-4,4′-bipyridinium tetrachloride) cell achieves a capacity density of ~12 Ah L − 1 and a low capacity fade rate of 0.0018% per cycle (or 0.0067% per hour). Organic catholytes for all-organic aqueous redox flow batteries have limited cycling lifetimes. Here, authors adjust the Hirshfeld charge of nitroxide radical derivatives to mitigate degradation, resulting in reduced capacity fade rate and extended battery lifetime.

HighlightsUltrathin (< 600 nm) and defect-free leaf-like UiO-66-SO3H membranes were fabricated via in situ smart growth.The sulfonated angstrom-sized ion transport channels in the membranes could accelerate the cation permeation (~ 3×  faster than non-functionalized UiO-66 membrane) and achieve a high ion selectivity (Na+/Mg2+ > 140).Metal–organic frameworks (MOFs) with angstrom-sized pores are promising functional nanomaterials for the fabrication of cation permselective membranes (MOF-CPMs). However, only a few research reports show successful preparation of the MOF-CPMs with good cation separation performance due to several inherent problems in MOFs, such as arduous self-assembly, poor water resistance, and tedious fabrication strategies. Besides, low cation permeation flux due to the absence of the cation permeation assisting functionalities in MOFs is another big issue, which limits their widespread use in membrane technology. Therefore, it is necessary to fabricate functional MOF-CPMs using simplistic strategies to improve cation permeation. In this context, we report a facile in situ smart growth strategy to successfully produce ultrathin (< 600 nm) and leaf-like UiO-66-SO3H membranes at the surface of anodic alumina oxide. The physicochemical characterizations confirm that sulfonated angstrom-sized ion transport channels exist in the as-prepared UiO-66-SO3H membranes, which accelerate the cation permeation (~ 3× faster than non-functionalized UiO-66 membrane) and achieve a high ion selectivity (Na+/Mg2+ > 140). The outstanding cation separation performance validates the importance of introducing sulfonic acid groups in MOF-CPMs.

Unlike inorganic crystals, metal-organic frameworks do not have a well-developed nanostructure library, and establishing their appropriately diverse and complex architectures remains a major challenge. Here, we demonstrate a general route to control metal-organic framework structure by a solvent-assisted ligand exchange approach. Thirteen different types of metal-organic framework structures have been prepared successfully. To demonstrate a proof of concept application, we used the obtained metal-organic framework materials as precursors for synthesizing nanoporous carbons and investigated their electrochemical Na + storage properties. Due to the unique architecture, the one-dimensional nanoporous carbon derived from double-shelled ZnCo bimetallic zeolitic imidazolate framework nanotubes exhibits high specific capacity as well as superior rate capability and cycling stability. Our study offers an avenue for the controllable preparation of well-designed meta-organic framework structures and their derivatives, which would further broaden the application opportunities of metal-organic framework materials. Metal-organic frameworks are promising for a range of applications, but architectural control is challenging. Here the authors use solvent-assisted ligand exchange to access a variety of metal-organic framework nanomaterials for precursors of nanoporous carbon with sodium ion storage properties.

While Ru owns superior catalytic activity toward hydrogen oxidation reaction and cost advantages, the catalyst deactivation under high anodic potential range severely limits its potential to replace the Pt benchmark catalyst. Unveiling the deactivation mechanism of Ru and correspondingly developing protection strategies remain a great challenge. Herein, we develop atomic Pt-functioned Ru nanoparticles with excellent anti-deactivation feature and meanwhile employ advanced operando characterization tools to probe the underlying roles of Pt in the anti-deactivation. Our studies reveal the introduced Pt single atoms effectively prevent Ru from oxidative passivation and consequently preserve the interfacial water network for the critical H* oxidative release during catalysis. Clearly understanding the deactivation nature of Ru and Pt-induced anti-deactivation under atomic levels could provide valuable insights for rationally designing stable Ru-based catalysts for hydrogen oxidation reaction and beyond. Despite the high intrinsic activity of Ru for hydrogen oxidation reaction, the surface oxidation-induced deactivation limits the application. Here, the authors report the introduction of Pt atoms could prevent the surface oxidation-related interfacial water network damage, preventing the deactivation of Ru.

Bipolar membrane electrolyzers present an attractive scenario for concurrently optimizing the pH environment required for paired electrode reactions. However, the practicalization of bipolar membranes for water electrolysis has been hindered by their sluggish water dissociation kinetics, poor mass transport, and insufficient interface durability. This study starts with numerical simulations and discloses the limiting factors of monopolar membrane layer engineering. On this foundation, we tailor flexible bipolar membranes (10 ∼ 40 µm) comprising anion and cation exchange layers with an identical poly(terphenyl alkylene) polymeric skeleton. Rapid mass transfer properties and high compatibility of the monopolar membrane layers endow the bipolar membrane with appreciable water dissociation efficiency and long-term stability. Incorporating the bipolar membrane into a flow-cell electrolyzer enables an ampere-level pure water electrolysis with a total voltage of 2.68 V at 1000 mA cm –2 , increasing the energy efficiency to twice that of the state-of-the-art commercial BPM. Furthermore, the bipolar membrane realizes a durability of 1000 h at high current densities of 300 ∼ 500 mA cm –2 with negligible performance decay. Bipolar membrane electrolyzers hold promise for water electrolysis but are limited by poor water dissociation and interface stability. Here, the authors report poly(terphenyl alkylene)-scaffold bipolar membranes that enhance water dissociation efficiency and enable durable pure water electrolysis.

Optimal pH conditions for efficient artificial photosynthesis, hydrogen/oxygen evolution reactions, and photoreduction of carbon dioxide are now successfully achievable with catalytic bipolar membranes-integrated water dissociation and in-situ acid-base generations. However, inefficiency and instability are severe issues in state-of-the-art membranes, which need to urgently resolve with systematic membrane designs and innovative, inexpensive junctional catalysts. Here we show a shielding and in-situ formation strategy of fully-interconnected earth-abundant goethite Fe +3 O(OH) catalyst, which lowers the activation energy barrier from 5.15 to 1.06 eV per HO − H bond and fabricates energy-efficient, cost-effective, and durable shielded catalytic bipolar membranes. Small water dissociation voltages at limiting current density (U LCD : 0.8 V) and 100 mA cm −2 (U 100 : 1.1 V), outstanding cyclic stability at 637 mA cm −2 , long-time electro-stability, and fast acid-base generations (H 2 SO 4 : 3.9 ± 0.19 and NaOH: 4.4 ± 0.21 M m −2 min −1 at 100 mA cm −2 ) infer confident potential use of the novel bipolar membranes in emerging sustainable technologies. Bipolar membranes integrated water dissociation and acid-base generations have great potential in emerging sustainable technologies but remains inefficient. Here, the authors circumvent this inefficiency and instability of the membranes by developing polyaniline shielded catalytic bipolar membranes.

Anion exchange membrane water electrolysis technology, which employs alkaline electrolytes, has emerged as a highly promising alternative to the acidic counterparts. However, the development of pure water-fed anion exchange membrane water electrolysis remains in its nascent stage, hindered by suboptimal ionomer performance, along with an unstable catalyst-ionomer interface induced by the Marangoni effect during the fabrication of catalyst layers. In this study, we introduce a strategy to overcome these challenges by employing in-situ covalent anchoring of the catalyst within cross-linked ionomer networks. Through synchrotron X-ray three-dimensional computed tomography characterization, complemented by extensive electrochemical analysis and multiphysics simulations, we demonstrate that the interconnected ionomer network substantially improves mass transport properties. Additionally, the covalently locked interfacial bonding effectively addresses delamination issues. Under rigorous pure water-fed conditions, our crosslink-immobilized catalyst layer demonstrates competitive durability (>1800 hours with a decay rate of 0.03 mV h −1 ) and performance (2.55 A cm −2 at 1.9 V). This approach presents an alternative paradigm for fabricating mechanically robust catalyst layers with enhanced durability and performance. Pure-water anion-exchange electrolysis is hindered by fragile ionomers and delaminating catalyst layers. Here, the authors report covalently anchoring catalysts within a cross-linked ionomer network, yielding a pure-water cell that delivers 2.55 A cm −2 at 1.9 V and runs over 1,800 h.

Mixed matrix membranes (MMMs) based on homochiral microporous materials have emerged as a promising approach for enantioselective separation. However, constructing MMMs for achieving efficient enantioselective separation at a high feed concentration still remains a great challenge due to the suboptimal interfacial compatibility. Here, we employ soluble porous organic cages (POCs) of intrinsic chiral sites as fillers to fabricate MMMs devoid of interfacial defects, exhibiting fast and selective enantioseparation for racemic 2-phenylpropionic acid with a flux of 2.93×10 -3  mol m -2 h -1 and an enantiomeric excess (ee) value up to 100% at a high concentration of 0.1 mol L -1 . The POC-based MMMs demonstrate a long-term operation stability with a low ee decline rate of 0.56% h -1 . This work reveals the imperative role of the microporous chiral environment in POCs for the enantioselective recognition and furnishes guidelines for the construction of POC-based membranes for efficient chiral separation. Mixed matrix membranes using homochiral microporous materials can be used for enantioselective separations, though optimizing selectivity at high feed concentration is challenging. Here the authors use porous organic cages for separations with high selectivity at high concentrations.

Studying ion transport in the interaction confinement regime has important implications for membrane design and advanced electrochemical devices. A key example is the rapid-charging capability of aqueous organic redox flow batteries, enabled by near-frictionless Na + /K + transport within triazine framework membranes. However, achieving similar breakthroughs for devices using anions ( e.g. , Cl - ) is challenging due to the suppression of anion transport under confinement, known as the charge asymmetry effect. We present a series of anion-selective covalent triazine framework membranes with comparable densities of subnanometer ion transport channels and identical micropore size distributions, which help to overcome the charge asymmetry effect and promote fast anion conduction. We demonstrate that regulating the charge distribution in the membrane frameworks reduces the energy barrier for anion transport, resulting in nearly doubled Cl - conductivity and adding almost no additional energy barrier for F - transport. This membrane enables an aqueous organic redox flow battery using Cl - ions to operate at high current densities, exceeding battery performance demonstrated by current membranes. These findings could benefit various electrochemical devices and inspire single-species selectivity in separation membranes. The suppressed Cl - transport under micropore confinement is a critical challenge. Here, authors report tailoring the pore chemistry of framework polymer membranes, which alters the interaction between Cl - and membranes and speeds Cl - transport, improving flow battery performance.