The challenge at the heart of this research is deceptively simple to state and notoriously hard to solve. Radioactive wastewater typically contains a cocktail of radionuclides, including cesium, strontium, and lanthanum species, whose ionic properties overlap to a remarkable degree. Cesium exists in solution as a monovalent cation, Cs+, while strontium and lanthanum appear as divalent Sr2+ and trivalent La3+ ions. Conventional separation technologies, ranging from chemical precipitation to adsorption and forward osmosis, struggle to discriminate between these species because differences in hydrated radius and charge are subtle. Yet precise separation matters enormously: safely disposing of nuclear waste, recycling nuclear resources, and minimizing environmental contamination all depend on isolating specific ions from complex mixtures.

The team, led by Ziwen Dai and Shushan Yuan of Huazhong University of Science and Technology in Wuhan, together with Pengrui Jin of KU Leuven and the University of Bath and collaborators in France and Korea, took their design cue from biology. Natural ion channels, such as the potassium channels found in cell membranes, achieve exquisite selectivity not through brute-force size exclusion alone but through precisely arranged binding sites that impose tuned energetic penalties on unwanted ions. Translating that principle to a synthetic membrane, the researchers constructed vertically aligned two-dimensional subnanochannels within graphene oxide lamellae and functionalized them with ethylenediaminetetraacetic acid, better known as EDTA. This chelating agent is famous in chemistry for its strong grip on metal ions, and here it serves as the molecular machinery that dictates which ions pass and which are held back.

The resulting GO-EDTA membrane contains stable, ordered channels whose internal functional groups exhibit strong, affinity-driven binding interactions with Sr2+ and La3+. In practical terms, the chemistry of the channel walls raises the diffusion energy barrier for multivalent ions far above that faced by monovalent Cs+. An ion crossing the membrane effectively must climb an energetic mountain, and the height of that mountain differs depending on the ion’s charge and its interaction with the EDTA groups. Because ion permeation rates depend exponentially on the barrier height according to transition-state theory, even modest differences in barrier energy translate into enormous differences in transport rates. This is precisely how the membrane achieves its headline performance: measured mono/multivalent ion selectivity reaches 485 for Cs+/Sr2+ and an extraordinary 1300 for Cs+/La3+.

What distinguishes this study from earlier work on graphene oxide membranes is the depth of the mechanistic analysis. Rather than reporting selectivity numbers alone, the researchers used a quartz crystal microbalance to dissect the overall energy barrier for salt transport into its two constituent contributions: partitioning at the pore mouth, where an ion must shed part of its hydration shell and enter the confined channel, and intrapore diffusion, where the ion migrates through the channel interior. The measurements revealed that the diffusion energy barrier is the dominant obstacle governing transmembrane ion transport, meaning that selectivity can be engineered by deliberately manipulating the energetic landscape inside the channels rather than merely adjusting their physical width. This insight reframes membrane design: instead of thinking of nanofiltration as a sieve, researchers can treat it as a tunable energetic landscape, much as enzyme chemists think about activation energies.

A crucial concern for any material destined for nuclear applications is resilience to radiation. Harsh irradiation environments degrade most organic polymers and many inorganic structures, causing swelling, embrittlement, or loss of functional groups. The GO-EDTA membrane passed this test: the channels maintained stable separation performance under irradiation conditions, a property the authors attribute to the inherent robustness of the graphene oxide scaffold and the stability of the aligned two-dimensional subnanochannel architecture. This radiation resistance is what moves the material from an elegant laboratory curiosity toward genuine deployment potential inside nuclear reprocessing facilities and wastewater treatment plants, where background radiation would rapidly compromise conventional polymeric membranes.

The practical payoff of the technology was demonstrated through electrodialysis experiments in which the membrane recovered cesium in the form of a purified CsCl product reaching a purity of 99.5 percent. That figure is significant beyond the laboratory. Cesium-137 is one of the most problematic fission products in nuclear waste, with a half-life of about thirty years and a chemistry that closely mimics potassium, allowing it to infiltrate biological systems. Capturing it selectively, in high purity, opens the possibility of converting a liability into a resource, since recovered cesium has applications in radiation sources and industrial gauges, while the decontaminated effluent becomes far easier and safer to manage. The same principle extends to strontium-90 and various actinide and lanthanide species that populate legacy waste tanks at sites such as Hanford and Sellafield.

The work also fits into a broader and rapidly accelerating scientific movement centered on confined ion transport in two-dimensional materials. Over the past decade, graphene oxide laminates have been shown to sieve ions through capillaries just a few angstroms wide, and related efforts have exploited metal-organic frameworks, MXenes, and covalent organic frameworks to create subnanometer transport pathways. Each of these platforms controls selectivity through some combination of steric exclusion, electrostatic repulsion, and dehydration penalties. The EDTA-functionalized graphene oxide membrane adds a powerful new lever to that toolbox: strong, chemically specific coordination interactions embedded within the channel walls, coupled with an explicit, experimentally validated understanding of how the diffusion energy barrier, rather than the partitioning barrier, dominates the separation.

The implications ripple outward beyond nuclear waste. Energy barrier engineering, as the authors describe it, offers a general design principle for any membrane application demanding high ion-ion selectivity: lithium extraction from magnesium-rich brines, where Li+ and Mg2+ share similar hydrated radii; the recovery of cobalt and nickel from battery recycling streams; and the removal of toxic heavy metals from industrial effluents. In each case, anchoring tailored chelating chemistry inside robust two-dimensional channels could deliver selectivity levels that conventional charge-based or size-based membranes cannot approach. The traceability of the mechanism, made possible by the quartz crystal microbalance measurements, means that future membrane designers can compute in advance how a given functional group will shift the transport energetics for a target ion pair.

Challenges remain before the technology reaches industrial scale. Fabricating large-area, defect-free GO-EDTA membranes with uniformly aligned channels will require process engineering that laboratory-scale methods do not yet provide, and long-term fouling behavior in genuinely complex waste matrices, which contain organic molecules, suspended solids, and competing ions in far greater variety than the model solutions tested here, must be established. Nevertheless, the combination of ultrahigh selectivity, radiation tolerance, demonstrated product recovery at 99.5 percent purity, and a clear mechanistic framework represents a milestone in membrane science. As the authors conclude, their work provides both a mechanism for designing membranes with high ion-ion selectivity and a concrete demonstration of the application potential of nuclear resource recycling, a message likely to resonate across environmental engineering, radiochemistry, and materials science in the years ahead.

The study was supported by the National Natural Science Foundation of China, the Innovation and Self-Development Research Fund of Huazhong University of Science and Technology, and the Hubei Provincial Science and Technology Research Project. The full article is available open access under a Creative Commons Attribution 4.0 license.

Supercapacitors are essential for the rapid charging and discharging of energy in various applications, from electric vehicles to renewable energy systems. However, conventional supercapacitors face limitations related to their electrolyte stability, environmental impact, and scalability. The newly developed device stands apart by incorporating a water-based electrolyte, buffered within the confines of sub-nanometer clay channels, which not only enhances performance but also introduces a level of environmental friendliness previously unattainable in this field.

At the heart of this innovation is the use of synthetic clay materials engineered to possess precisely 1-nanometer-wide channels. These channels provide highly confined pathways for electrolyte ions, significantly impacting ion transport dynamics and electrochemical stability. The constrained nanochannels effectively attenuate the deleterious effects that typically plague aqueous electrolytes, such as evaporation, leakage, and limited voltage windows, without compromising the ionic conductivity crucial for high performance.

The research team meticulously characterized the physicochemical properties of these clay channels, demonstrating their ability to hold and direct water molecules and ions with unprecedented precision. This molecular confinement alters the structure and dynamics of the aqueous environment, showcasing distinct behaviors compared to bulk water. The result is a supercapacitor electrolyte where ion mobility is optimized, and unwanted side reactions are suppressed, culminating in enhanced device longevity and efficiency.

One of the most striking features of the all-water supercapacitor is its voltage window, which surpasses conventional aqueous systems. Typically, water-based electrolytes struggle to exceed voltages of about 1.23 volts due to water splitting. However, the 1-nm clay channels create a unique microenvironment that elevates the voltage threshold without triggering deleterious electrochemical reactions. This breakthrough could open avenues for aqueous supercapacitors to manage energy with higher densities, rivaling those of organic solvent-based counterparts, while maintaining safety and eco-friendliness.

Furthermore, the fabrication process used to integrate the 1-nm clay channels into the supercapacitors emphasizes scalability and environmental consciousness. The researchers utilized abundant and inexpensive clay minerals as templates, which can be synthesized and processed through water-based chemical methods. This approach not only reduces the cost barrier traditionally associated with nanoscale engineering but also aligns with sustainable manufacturing paradigms vital for scaling next-generation energy storage devices to real-world applications.

Electrochemical performance tests revealed remarkable capacitance retention over thousands of charge-discharge cycles, showcasing the device’s potential for practical use where durability is paramount. The suppression of electrolyte degradation and mechanical stability under repeated cycling attest to the mechanical robustness of the clay-based channel structures. The water-based electrolyte also imparts safety benefits by mitigating risks associated with flammability and toxicity prevalent in organic electrolyte systems.

Beyond energy storage, the 1-nm clay channel framework exhibits promising implications for ion sieving and selective ion transport technologies. The profound control over ionic pathways demonstrated in this work could influence the design of other functional devices in sensing, filtration, and catalysis. This study exemplifies how the marriage of naturally occurring materials with nanoscale engineering can unlock multifunctional platforms with transformative technological potential.

The interdisciplinary approach employed in the study combines mineralogy, electrochemistry, materials science, and nanofluidics. By harnessing the natural affinity of water molecules to confined spaces, the team created an entirely new electrolyte paradigm. These insights deepen scientific understanding of how confined water behaves differently from bulk water, influencing charge storage and transfer processes at the molecular level.

Looking forward, the prospects for integrating this technology into commercial devices appear highly promising. The compatibility of the all-water supercapacitor with existing manufacturing protocols, combined with its enhanced sustainability and performance metrics, makes it an attractive candidate for next-generation energy storage. The researchers envision applications extending from portable electronics to grid-scale renewable energy stabilization, where safety, cost, and environmental impact are critical considerations.

As demand for rapid, safe, and sustainable energy storage solutions surges worldwide, breakthroughs like the all-water supercapacitor enabled by 1-nanometer clay channels reinforce the importance of exploring unconventional materials and nanoscale phenomena. This work not only advances supercapacitor technology but offers an inspiring example of how nature-inspired nanotechnology can forge new paths toward a clean energy future.

The study also highlights the importance of fundamental research into the interplay between materials structure and electrochemical behavior. Uncovering how the nano-confined water environment alters ion hydration and electrochemical stability provides a foundation for further innovations. The strategic use of layered clay minerals introduces a versatile platform to tailor electrolyte properties precisely, potentially enabling customized energy storage solutions optimized for specific applications.

While challenges remain, such as optimizing device integration and upscaling manufacturing techniques, the implications of this discovery extend far beyond the laboratory. The 1-nm clay channel supercapacitor could herald a new era of high-performance, environmentally benign energy storage devices that address both the technological and ecological demands of modern society.

Ultimately, the work by Artemov and colleagues embodies the cutting edge of energy materials research, merging detailed nanostructural engineering with the pragmatic requirements of real-world application. Their pioneering results demonstrate that harnessing the governing principles of nanoscale confinement and water chemistry can yield unprecedented performance breakthroughs, with profound societal implications for sustainable technological advancement.

Subject of Research: Development of an all-water supercapacitor utilizing 1-nanometer clay channels to enhance energy storage performance and environmental sustainability.

Article Title: All-water supercapacitor enabled by 1-nm clay channels.

Article References:
Artemov, V., Babiy, S., Teng, Y. et al. All-water supercapacitor enabled by 1-nm clay channels. Nat Commun 17, 5014 (2026). https://doi.org/10.1038/s41467-026-73924-1

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41467-026-73924-1