In a review published in Nature Water, scientists led by Matthew Landsman of Arizona State University and Lawrence Berkeley National Laboratory, together with colleagues from SLAC National Accelerator Laboratory, Oak Ridge National Laboratory, Brookhaven National Laboratory, Argonne National Laboratory and several universities, lay out a detailed case for expanding the use of synchrotron X-ray and neutron techniques in water treatment research. These facilities, which accelerate electrons to near light speed or generate intense beams of neutrons, have transformed fields from structural biology to battery development. Yet the water treatment community, the authors contend, remains a strikingly small fraction of their user bases, leaving transformative research opportunities untapped.

The technical argument rests on what these beams can actually reveal. Synchrotron X-rays are extraordinarily bright and tunable, spanning energies from tender X-rays that probe light elements like carbon and nitrogen to hard X-rays that penetrate thick samples and resolve atomic coordination around metals. Techniques such as X-ray absorption spectroscopy can determine the oxidation state and local bonding environment of contaminants like arsenic or chromium in real water matrices. Small-angle X-ray scattering can measure the size and arrangement of colloids and polymers in solution. X-ray computed tomography can map the three-dimensional internal structure of membranes and porous sorbents at resolutions reaching tens of nanometers. Neutrons, meanwhile, offer a complementary superpower: they are exceptionally sensitive to hydrogen, meaning they can directly visualize water itself as it moves through materials, something X-rays struggle to do because hydrogen scatters X-rays so weakly.

What makes the review particularly compelling is its emphasis on in situ and operando experiments, meaning studies conducted while a treatment process is actually running under realistic conditions. Traditional characterization typically requires drying, freezing or otherwise preparing samples, which can fundamentally alter the structures being studied. Modern user facilities increasingly offer sample environments that allow researchers to study flowing water, applied voltages, pressure and temperature while collecting data. The authors point to examples such as operando small-angle neutron scattering studies of silica fouling in reverse osmosis systems, in situ X-ray scattering measurements of concentration polarization layers during cross-flow ultrafiltration, and operando ambient-pressure X-ray photoelectron spectroscopy that directly probes the chemistry of polymer membranes as they absorb water and ions.

These dynamic measurements matter because water treatment performance is governed by nanoscale processes that unfold in real time. Fouling, the accumulation of unwanted material on membranes and sorbents, is a prime example. It is the dominant cost driver in membrane-based desalination and water reuse, yet its molecular origins remain poorly understood. X-ray and neutron techniques can reveal the composition, structure and evolution of fouling layers as they form, distinguishing between mineral scaling, organic adsorption and biofilm development. The authors cite work using X-ray absorption spectroscopy to identify the mechanisms of calcium and silicon fouling on reverse osmosis membranes in wastewater reclamation, and neutron reflectometry studies that expose the interfacial microenvironment driving electrochemical reactions.

The review also highlights opportunities in three specific technology areas where facility access could accelerate progress. Membranes for brine management, including zero and minimal liquid discharge systems, could benefit from molecular-level understanding of ion transport and membrane structure. Catalysts for contaminant degradation, such as single-atom catalysts embedded in membranes that activate hydrogen peroxide to destroy pollutants, could be characterized under operating conditions to identify their true active sites. Sorbents for resource recovery, including materials that selectively capture phosphate, ammonia nitrogen or critical minerals from wastewater, could be optimized by directly observing how their binding sites interact with target ions in complex water matrices.

Neutron techniques deserve particular attention in this context because of their unique sensitivity to light elements and their ability to distinguish isotopes. Hydrogen-deuterium contrast neutron radiography, for instance, can track water exchange and two-phase flow in porous materials by substituting heavy water for normal water. Quasielastic neutron scattering can measure the dynamics of confined water in polymer membranes on picosecond to nanosecond timescales, revealing how water molecules move through the aromatic polyamide layers of reverse osmosis membranes. These measurements directly connect molecular motion to macroscopic water permeability, offering a level of mechanistic insight that conventional laboratory techniques cannot match.

The authors also emphasize the growing role of advanced computational modelling coupled with facility experiments. Machine learning is increasingly used to process the enormous datasets generated by modern detectors, such as the 500-kilopixel X-ray photon correlation spectroscopy measurements that resolve dynamics on microsecond timescales. Multimodal experiments that combine X-ray and neutron tomography simultaneously, such as the NeXT system at the National Institute of Standards and Technology, allow researchers to register complementary information about structure and water distribution in the same sample. The integration of artificial intelligence with high-throughput scattering and imaging is proposed as part of a next-generation discovery pipeline that could dramatically accelerate materials development.

Access to these facilities is more attainable than many water researchers realize. User facilities at national laboratories typically provide beamtime free of charge to researchers whose proposals are accepted through competitive peer review, and many offer dedicated staff scientists who help design experiments and operate complex sample environments. The authors argue that expanding the user base at these facilities will require deliberate outreach, training programs and the development of standardized experimental workflows that lower the barrier to entry for water treatment researchers unfamiliar with synchrotron or neutron techniques.

The stakes extend well beyond academic curiosity. The authors frame their argument in terms of global water, resource and energy security, noting that molecular-level design insights bridge laboratory-scale discoveries to system-level improvements in real treatment infrastructure. As climate change intensifies water scarcity and as industries seek to recover valuable materials from waste streams, the ability to rationally design next-generation membranes, catalysts and sorbents becomes increasingly urgent. The review suggests that the water treatment community stands at a threshold, where the sophisticated characterization infrastructure built over decades at national laboratories could finally be brought to bear on one of humanity’s most fundamental challenges: ensuring clean water for all.

Subject of Research: Water treatment research opportunities at synchrotron and neutron user facilities

Article Title: Water treatment research opportunities at synchrotron and neutron user facilities

Article References: Landsman, M. R., Hesse, S. A., Aydogan-Gokturk, P., Yao, C., Bechtel, H. A., Dudchenko, A. V., Hexemer, A., Jiang, Z., Katz, L. E., Kumar, M., Urban, V. S., Waluyo, I., Mauter, M. S., Tassone, C. J., & Crumlin, E. J. (2026). Water treatment research opportunities at synchrotron and neutron user facilities. Nature Water, 4(10), 1244-1258. https://doi.org/10.1038/s44221-026-00723-9

Image Credits: AI Generated

DOI: 10.1038/s44221-026-00723-9

Keywords: synchrotron, neutron scattering, water treatment, membranes, desalination, fouling, X-ray absorption spectroscopy, operando characterization, user facilities, Nature Water, Water, treatment

The starting point for the study was a class of materials known as two-dimensional transition metal dichalcogenides, or TMDs. In these compounds, a sheet of transition metal atoms is sandwiched between two sheets of chalcogen atoms, in this case selenium, forming layers just a few atoms thick. Molybdenum diselenide and its relatives can crystallize in two main arrangements: the hexagonal 2H phase, which is semiconducting, and the octahedrally coordinated 1T phase, which tends to be metallic and therefore far better at moving charge during electrocatalysis. Pristine TMDs suffer from low conductivity and weak hydrogen adsorption, and researchers have spent years trying to fix these flaws through vacancy creation, doping, intercalation, and alloying. The new study combines several of these tricks at once, and the result is a material whose catalytic behavior exceeds the sum of its parts.

Synthesis was carried out by colloidal chemistry, a technique more familiar from the production of quantum dots than from industrial electrocatalysts. The researchers dissolved ruthenium chloride, molybdenum chloride, niobium chloride, and vanadium chloride together with dibenzyl diselenide in oleylamine, then injected the mixture into a hot flask held at 260 degrees Celsius. By systematically varying the fraction of the ruthenium precursor from zero all the way to one, while keeping the other three metals in equal proportion, they produced a family of nine samples spanning the full compositional range. The products were then annealed at either 400 or 600 degrees Celsius under argon flow. Crucially, energy-dispersive X-ray spectroscopy confirmed that the composition of each product faithfully mirrored the recipe of precursors fed into the reaction, giving the team precise control over the final alloy.

What happened next is where the story becomes genuinely surprising. At zero ruthenium content, the material formed flower-like aggregates of layered nanosheets with the expected 2H structure. As ruthenium was added, the nanosheets shrank in lateral size but kept their layered form, and a new crystal phase began to emerge. X-ray diffraction revealed that starting at a ruthenium fraction of 0.25, the cubic pyrite phase characteristic of ruthenium diselenide appeared alongside the layered phases, and a previously unassigned diffraction peak turned out to belong to the 1T phase. In other words, adding ruthenium did not merely dilute the original alloy; it triggered a structural transformation from the semiconducting 2H arrangement toward the metallic 1T arrangement, while the nanosheet morphology survived across nearly the whole composition range.

Atomic-resolution scanning transmission electron microscopy provided the definitive proof that the four metals were genuinely mixed at the atomic scale rather than segregated into separate domains. Ruthenium, molybdenum, and niobium, whose atomic numbers are too similar to distinguish in these images, appeared uniformly distributed, and vanadium showed no tendency to cluster. Fast Fourier transform analysis of the images confirmed the coexistence of 2H and 1T regions in the mid-composition samples and the dominance of the cubic phase in pure ruthenium diselenide. X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements then traced the electronic consequences: ruthenium incorporation lowered the oxidation states of vanadium and niobium, enhanced the metallic character of the material, and confirmed that every ruthenium atom was coordinated to selenium rather than to other ruthenium atoms.

To understand why the 1T phase becomes favorable, the team turned to density functional theory, constructing supercells of 150 atoms in which the four metals were randomly distributed. The calculations showed that in the pristine, vacancy-free models the 2H phase remained more stable, but by margins that shrank rapidly as ruthenium content increased. The decisive ingredient turned out to be selenium vacancies. The annealed alloy samples carried an average of about 8 percent selenium vacancies, and when the theorists built these vacancies into their models, the energy gap between the 1T and 2H phases narrowed dramatically. The vacancies preferentially formed near vanadium sites, which explains why vacancy concentrations dropped at the highest ruthenium loadings. In effect, the defects and the alloying worked together to tip the thermodynamic balance toward the catalytically superior metallic phase.

The electrochemical measurements are where the practical payoff becomes vivid. In 1 molar potassium hydroxide, the original ternary alloy without ruthenium required an overpotential of 265 millivolts to drive a current density of 10 milliamperes per square centimeter. The quaternary alloys with ruthenium fractions between 0.16 and 0.4 slashed that figure to between 36 and 40 millivolts, with the best sample, at a ruthenium fraction of 0.4, delivering 36 millivolts and a Tafel slope of 61 millivolts per decade. For context, commercial platinum-on-carbon needed 21 millivolts under the same conditions. In 0.5 molar sulfuric acid the quaternary alloys cut the overpotential from 137 to as low as 82 millivolts, and in neutral phosphate buffer the improvement was even more dramatic, falling from 503 to 139 millivolts, essentially matching the 145 millivolts of the platinum reference. Chronoamperometry showed negligible current decay over five days of continuous operation, and post-test analysis confirmed the catalyst’s structure and composition were intact.

The theoretical descriptor that ties these results together is the Gibbs free energy of hydrogen adsorption, often abbreviated as delta G of H-star. An ideal catalyst binds hydrogen neither too weakly nor too strongly, giving a value near zero. On the basal selenium atoms of the pristine 2H phase, the calculated values ranged from 0.74 to 1.55 electron volts, far too positive for efficient catalysis. But at selenium vacancy sites, where hydrogen could bind directly to exposed metal atoms, the values collapsed toward zero: minus 0.13 electron volts at a ruthenium-vanadium-niobium site, minus 0.087 electron volts at a pair of ruthenium atoms, and a remarkable 0.0055 electron volts at a ruthenium-vanadium pair in the 1T phase. Every near-optimal site involved at least one ruthenium atom, identifying ruthenium as the key catalytic species while the surrounding metals tuned the electronic environment.

Perhaps the most technically ambitious part of the study was the use of operando X-ray absorption spectroscopy, which allowed the researchers to watch the catalyst’s electronic structure change in real time as voltage was applied in alkaline electrolyte. As the overpotential increased, the white-line intensity of the ruthenium, molybdenum, and niobium absorption edges decreased, signaling that all three metals became more metallic under working conditions. Fitting of the extended absorption data revealed that in the quaternary alloy, ruthenium atoms formed bonds with oxygen species from adsorbed water or hydroxide, with a ruthenium-oxygen distance of 1.94 angstroms, while the ruthenium-selenium bonds contracted slightly. In the pure cubic ruthenium diselenide, only the bond contraction appeared. This suggests the quaternary alloy is better at adsorbing the electrolyte, a critical step in alkaline hydrogen evolution where water molecules must first be split before hydrogen can be released.

Taken together, the results sketch a coherent design principle for next-generation hydrogen catalysts. Ruthenium incorporation drives a phase transition toward the metallic 1T structure, selenium vacancies expose highly active metal sites where hydrogen binds with near-thermoneutral energy, the multi-metal composition enhances metallicity across the entire electronic structure, and the nanosheet geometry maximizes the surface area available for reaction. The optimum sits at a ruthenium fraction of 0.4, beyond which performance plateaus and then declines as vacancies become scarcer. Because ruthenium is dramatically cheaper than platinum and the alloy uses only modest amounts of it, the approach offers a credible route toward electrodes that approach platinum-class performance without platinum-class cost. If the colloidal synthesis can be scaled from millimole batches to industrial production, four-metal nanosheets like these could become a cornerstone of the green hydrogen economy that climate targets increasingly demand.

Subject of Research: Two-dimensional quaternary transition metal dichalcogenide alloy nanosheets for electrocatalytic hydrogen evolution

Article Title: Two‐Dimensional Quaternary Alloys of (RuMoVNb)Se2 for Superior Hydrogen Evolution Reaction Catalysis

Article References: Ihsan, J., Kim, J. Y., Mishal, I., Choi, J. H., Eun An, J., Choi, Y. J., Kim, D., Kwak, I. H., Vilé, G., Kwon, I. S., Kang, H. S., & Park, J. (2026). Two‐Dimensional Quaternary Alloys of (RuMoVNb)Se 2 for Superior Hydrogen Evolution Reaction Catalysis. Advanced Science, 13(56), Article e76600. https://doi.org/10.1002/advs.76600

Image Credits: AI Generated

DOI: 10.1002/advs.76600

Keywords: hydrogen evolution reaction, transition metal dichalcogenides, quaternary alloy, ruthenium diselenide, electrocatalysis, green hydrogen, 1T phase, selenium vacancies, colloidal synthesis, DFT calculations, X-ray absorption spectroscopy, nanosheets

The work, published in Advanced Composites and Hybrid Materials, tackles a problem that has haunted fuel cell developers for decades. Conventional catalysts consist of platinum nanoparticles dispersed on carbon black, a material known in the trade as Pt/C. The bond between platinum and plain carbon is weak, so under the harsh, acidic, voltage-cycling conditions inside a working fuel cell, the tiny platinum particles gradually dissolve, migrate, and clump together. As the particles merge, the amount of exposed catalytic surface shrinks, and the fuel cell steadily loses power. The new study identifies this weak metal-support interaction as the root cause of the instability and sets out to fix it not by adding more platinum, but by rewiring the electrons at the interface.

The researchers’ strategy, which they call interfacial charge engineering, involves constructing heterostructures in which platinum is intimately coupled to molybdenum carbide, Mo2C, all supported on nitrogen-doped carbon. Molybdenum carbide is a fascinating material in its own right; sometimes nicknamed the ceramic that behaves like a metal, it conducts electrons well and forms strong chemical bonds with noble metals. By bringing platinum and molybdenum carbide into direct contact, the team created an interface where electrons are no longer content to stay put. Instead, charge redistributes directionally across the junction, and it is this deliberate electronic rearrangement that lies at the heart of the catalyst’s remarkable performance.

Manufacturing such precisely tuned nanoscale architectures is often the stumbling block that separates elegant laboratory concepts from practical technology. Here the team employed a scalable synthesis based on in-situ concurrent pyrolysis and reduction, a one-step thermal process in which the precursor materials transform simultaneously into the final composite. Rather than assembling platinum particles and carbide supports separately and hoping they bond, the method grows the heterostructure directly, ensuring that the electronic coupling between the two phases is established from the moment of formation. That scalability matters enormously for any catalyst hoping to leave the laboratory, since fuel cell deployment on the scale required for a hydrogen economy demands manufacturing routes that do not depend on painstaking, batch-by-batch nanofabrication.

Proving that the platinum and molybdenum carbide truly interact at the electronic level required sophisticated structural detective work. The team turned to X-ray absorption fine structure spectroscopy, a synchrotron-based technique that reveals the local atomic environment of specific elements. The measurements uncovered a distinct platinum-molybdenum bond measuring approximately 2.72 angstroms, with a platinum-molybdenum coordination number of about 1.81. In plain terms, each platinum atom at the interface is directly bonded to roughly one to two molybdenum neighbors, a signature of genuine chemical contact rather than mere physical proximity. This direct bonding is the structural foundation on which the entire charge-engineering concept rests, because electrons can only flow efficiently between phases that are chemically connected.

Theoretical calculations using density functional theory, performed on the Hefei Advanced Computing Center, illuminated what that charge flow actually does. The heterostructured interface, the computations showed, functions as an electronic reservoir, pulling and pushing charge in a directed manner across the platinum-molybdenum carbide boundary. The consequence is a downshift of the d-band center of the interfacial platinum atoms, a fundamental descriptor in catalysis theory that governs how strongly molecules stick to a metal surface. When the d-band center sits too high, oxygenated intermediates such as hydroxyl species bind too tightly and refuse to leave, poisoning the surface. By lowering the d-band center, the charge redistribution weakens those over-strong bonds just enough, optimizing the binding strength of oxygenated intermediates and allowing the reaction to proceed faster.

The electrochemical results were striking. The engineered Pt-Mo2C/NC catalyst delivered a mass activity of 0.65 amperes per milligram of platinum at 0.9 volts, the benchmark potential used to compare oxygen reduction catalysts worldwide. That figure represents a 4.8-fold improvement over commercial Pt/C, meaning the new catalyst extracts nearly five times more current from every precious gram of platinum. Since platinum can cost more than gold and fuel cell economics hinge on minimizing the platinum loading, multiplying its efficiency by nearly five is precisely the kind of leap that could reshape the cost calculations for hydrogen vehicles and stationary power systems alike.

Activity alone, however, has never been the fuel cell industry’s hardest problem; durability is. A catalyst that performs brilliantly on day one but fades within weeks is commercially useless, and this is where the interfacial design truly shines. The robust platinum-molybdenum carbide coupling anchors the platinum atoms in place and effectively suppresses both dissolution and agglomeration, the twin killers of conventional catalysts. After 20,000 potential cycles, an accelerated stress test that simulates years of start-stop driving, the catalyst retained approximately 90 percent of its initial mass activity. For comparison, conventional platinum-on-carbon catalysts typically lose far more of their activity under equivalent testing, which is exactly why the weak metal-support interaction was flagged as the central obstacle in the first place.

What makes this study resonate beyond a single material system is the generality of its design principle. Rather than discovering an accidental winner, the researchers demonstrated a rational recipe: choose a support that forms strong interfacial bonds with the catalytic metal, engineer directional charge transfer across that interface, and use the resulting electronic modulation to tune the binding energies of reaction intermediates. The same logic could, in principle, be applied to other catalytic metals and other carbide, nitride, or phosphide supports, opening a pathway toward a whole family of active, durable electrocatalysts designed from first principles rather than trial and error. The work also underscores how modern synchrotron spectroscopy and computational chemistry now work hand in hand, allowing scientists to see the bonds they are engineering and predict their consequences before a single electrochemical test is run.

The road from a published paper to a commercial fuel cell stack is long, involving membrane electrode assembly integration, real-world impurity tolerance, and mass production at scale, and the study, released as an open-access article with a permanent DOI, will now face the scrutiny of the wider electrocatalysis community. Yet the combination of a scalable synthesis, a mechanistic understanding grounded in atomic-scale evidence, and durability numbers that survive a punishing 20,000-cycle stress test gives this interfacial charge engineering strategy a credibility that many catalyst reports lack. If the approach transfers smoothly from the rotating disk electrodes of the laboratory to the membrane electrode assemblies of real fuel cells, the humble interface between a platinum atom and a molybdenum carbide support may come to be remembered as the place where the hydrogen economy finally found its footing, one carefully redistributed electron at a time.

Subject of Research: Interfacial charge engineering of platinum-molybdenum carbide heterostructures for the oxygen reduction reaction in fuel cells

Article Title: Interfacial charge engineering of Pt-Mo2C heterostructures for robust oxygen reduction reaction

Article References: Han, Y., Wang, Y., Wang, Q., Zheng, X., Lu, S., Zeng, Y., Hua, Q., Jia, C., Donkor, S., & Xu, B. B. (2026). Interfacial charge engineering of Pt-Mo2C heterostructures for robust oxygen reduction reaction. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02109-7

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02109-7

Keywords: oxygen reduction reaction, fuel cells, platinum catalyst, molybdenum carbide, interfacial charge engineering, electrocatalysis, heterostructures, metal-support interaction, d-band center, catalyst durability, X-ray absorption spectroscopy, density functional theory

The catalyst in question belongs to the zinc–chromium oxide family, a workhorse system for high-temperature methanol synthesis and, more recently, for the direct conversion of syngas to light olefins such as ethylene and propylene—the building blocks of plastics. In 2016, the landmark OX/ZEO process demonstrated that metal oxides could steer syngas chemistry away from conventional Fischer–Tropsch distributions toward selectively formed olefins, igniting intense interest in which surface features govern that selectivity. Computational work by Zhi-Pan Liu and Sicong Ma had earlier suggested that dynamic coordination of zinc and chromium cations plays a decisive role, but the identity and location of the active oxygen defects remained unresolved. The new study closes that gap by making the invisible visible.

The central methodological innovation is a site-resolved analytical platform that fuses operando, time-resolved energy-dispersive X-ray absorption spectroscopy with mass spectrometry, transient kinetic analysis, and microcalorimetry. Energy-dispersive X-ray absorption spectroscopy, or EDXAS, acquires full absorption spectra in milliseconds, allowing the researchers to track changes in the chromium and zinc local environments while the catalyst was actually working under realistic syngas feed. By pairing these rapid spectral snapshots with simultaneous product monitoring and then applying transient kinetic analysis—the mathematical dissection of how product signals respond to deliberate perturbations of the feed—the team could correlate specific spectral signatures with specific catalytic functions. Calorimetry added the thermodynamic dimension, measuring the heat released or absorbed as oxygen vacancies formed and were consumed.

Why is such sophistication necessary? Conventional tools for identifying oxygen vacancies, such as X-ray photoelectron spectroscopy, suffer from well-documented ambiguities: the oxygen 1s signal often attributed to vacancies in the 531–532 electron-volt range can arise from hydroxyl groups or other surface species instead, a pitfall highlighted in recent critical analyses of ZnO spectra. Moreover, vacancies exist at vanishingly low concentrations on a heterogeneous surface that may contain terraces, steps, dopants, and metal–oxide junctions all at once. Electron microscopy can image vacancies in exceptional cases, but typically under conditions far removed from working reactors. The new approach sidesteps these limitations by measuring the catalyst under genuine reaction conditions and resolving the vacancy population into distinct site types rather than a single averaged count.

What the team found is strikingly specific. Isolated chromium(III) dopants sitting at the Cr/ZnO interface selectively stabilize a particular class of oxygen vacancy—stoichiometric vacancies located at Zn–O–Cr bridge sites—both thermodynamically and kinetically. In other words, these interfacial positions are the easiest places to remove an oxygen atom, and once removed, the vacancy lingers there preferentially rather than migrating elsewhere. Density functional theory calculations, performed by Liu’s group with global structure searches, rationalize this preference: the chromium cation’s electronic structure compensates the charge and strain associated with vacancy formation, lowering the energetic penalty precisely at the interface. The result is a self-assembled ensemble of Cr–O(v) motifs—chromium cations adjacent to oxygen vacancies—that behave as a distinct chemical species with its own reactivity.

And that reactivity is remarkable. The site-specific Cr–O(v) motifs exhibit exceptionally high activity and selectivity for converting syngas into olefins, outperforming the rest of the surface by a wide margin. Meanwhile, the study assigned a second, complementary role to the interfacial oxygen atoms themselves: they serve as the active sites for propane dehydrogenation, the reverse-type reaction in which hydrogen is stripped from propane to form propylene. This dual assignment is conceptually elegant. At the very same interface, the presence of an oxygen atom enables dehydrogenation chemistry, while its absence enables hydrogenation and C–C coupling chemistry leading to olefins. The catalyst’s selectivity is thus dictated by which of these two interfacial states dominates under a given feed, a balance the researchers could quantify through their transient kinetic framework.

The experimental campaign drew on major synchrotron infrastructure. X-ray absorption measurements were conducted at the BL05U, BL20U, and BL14W beamlines of the Shanghai Synchrotron Radiation Facility, with microscopic infrared measurements performed at the BL06B beamline. The combination of rapid energy-dispersive acquisition with mass spectrometric product detection meant that every fluctuation in catalyst structure could be time-stamped against fluctuations in catalytic output. Microcalorimetry experiments, carried out by Rui Ma and Xiao Kong, anchored the energetic analysis, while Bader charge analysis of the computed models clarified how electron density redistributes when an interfacial oxygen is removed. The optimized atomic coordinates for all computational models were deposited publicly on Figshare, reflecting a commitment to reproducibility that accompanies the paper’s extensive source data.

Beyond the specific zinc–chromium system, the significance of this work lies in its transferable methodology. The pairing of operando transient kinetic analysis with energy-dispersive X-ray absorption spectroscopy constitutes, in the authors’ framing, a platform for tuning surface defect chemistry in oxide catalysts generally. Oxygen vacancies are implicated in an enormous range of transformations: carbon monoxide and carbon dioxide hydrogenation, oxidative dehydrogenation of light alkanes, water–gas shift chemistry, and photocatalytic water splitting, to name a few. In ceria, titania, and countless mixed oxides, the vacancy has been invoked as the active site, the charge reservoir, or the oxygen shuttle—but usually without site-level proof. A method that delivers quantitative, site-resolved vacancy counts under working conditions offers the catalysis community a way to move from correlational arguments to causal ones: to state not merely that vacancies exist, but which vacancies, where, doing what.

The practical implications extend to industrial chemistry. Syngas, produced from coal, natural gas, or biomass gasification, is a foundational feedstock, and routes that bypass energy-intensive intermediate steps to deliver olefins directly carry substantial economic and environmental weight. Knowing that isolated Cr(III) dopants at oxide interfaces nucleate the catalytically potent vacancies gives catalyst designers an actionable blueprint: control the dopant distribution, control the interface density, and thereby control the population of the most active sites. The same logic applies in reverse for propane dehydrogenation, where preserving interfacial oxygen rather than removing it defines the design target. As the chemical industry seeks to electrify and decarbonize, rational defect engineering of mixed-oxide catalysts—guided by operando, site-resolved spectroscopy—may prove one of the most powerful levers available, and this study provides a compelling demonstration of what that lever looks like when it is finally pulled with precision.

Subject of Research: Site-resolved identification of catalytically active oxygen vacancies at Cr/ZnO interfaces during syngas conversion

Article Title: Preferential locations of catalytically active oxygen vacancies at Cr/ZnO interfaces during syngas conversion

Article References: Yang, C., Ma, R., Zhang, C., Kong, X., Ding, B., Li, R., Ma, S., Liu, Z.-P., Cao, Y., Fu, Q., Yang, F., Bao, X., & Zhu, Y. (2026). Preferential locations of catalytically active oxygen vacancies at Cr/ZnO interfaces during syngas conversion. Nature Catalysis. https://doi.org/10.1038/s41929-026-01615-7

Image Credits: AI Generated

DOI: 10.1038/s41929-026-01615-7

Keywords: oxygen vacancies, Cr/ZnO interface, syngas conversion, olefins, heterogeneous catalysis, operando spectroscopy, X-ray absorption spectroscopy, transient kinetic analysis, propane dehydrogenation, zinc–chromium oxide, defect chemistry, microcalorimetry

The material at the heart of the study is a bilayer nickelate, a compound in which pairs of nickel-oxide planes are stacked with a spacing of just a few angstroms. In these structures, each nickel atom sits at the center of an oxygen octahedron, and the electronic states near the Fermi level are dominated by nickel 3d orbitals. Two of these orbitals matter most. The dx2-y2 orbital extends within each plane and governs the in-plane conduction, much as it does in cuprate superconductors. The dz2 orbital, by contrast, points along the crystallographic c axis, out of the plane, and can overlap with the pz orbitals of apical oxygen atoms sitting above and below the nickel. This overlap creates a potential pathway for electrons to hop coherently from one layer to its partner in the bilayer.

Theoretical work had long suggested that this interlayer channel could be crucial. Calculations published since 2023 proposed that pressure-driven changes in the bilayer structure enhance dz2 orbital character at the Fermi level, enabling interlayer pairing mechanisms that range from s-wave states with sign changes between sheets of the Fermi surface to interlayer valence bond scenarios. But theory alone could not settle the matter, because the experiments needed to test these ideas, soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering, are notoriously difficult to perform on superconducting nickelate samples. The materials are chemically sensitive, their surfaces degrade in air, and the superconducting fraction within bulk crystals is often inhomogeneous, making it hard to attribute spectroscopic signatures unambiguously to the superconducting phase.

The Chinese-led collaboration overcame this obstacle with a clever materials engineering strategy. They grew thin films of the bilayer nickelate (La,Pr)3Ni2O7 by pulsed laser deposition and protected them with a capping layer that preserves the delicate oxygen stoichiometry of the buried superconducting layers. Crucially, the team prepared a series of films spanning three distinct electronic ground states: insulating, metallic and superconducting. This controlled family of samples gave the researchers something no single superconducting crystal could provide, namely the ability to track how the electronic structure evolves as the material crosses from one quantum state to another, isolating the features that appear only when superconductivity does.

With the capped films in hand, the researchers deployed the full arsenal of modern synchrotron spectroscopy. X-ray absorption spectroscopy at the oxygen K edge and the nickel L3 edge probed the unoccupied electronic states, revealing the orbital character of the charge carriers. Resonant inelastic X-ray scattering, or RIXS, at the nickel L3 edge then measured the energy and momentum resolved spectrum of orbital excitations and spin excitations, the collective magnetic fluctuations that many theorists believe mediate pairing in unconventional superconductors. Resonant elastic X-ray scattering complemented these measurements by detecting static magnetic order, specifically the spin-density-wave order that competes with superconductivity in these compounds.

The results paint a coherent and strikingly clear multiorbital picture. Across all samples, the in-plane electronic structure is built from itinerant dx2-y2 states, which form the conductive backbone of the material regardless of whether the sample insulates, conducts or superconducts. What separates the superconductors from the rest is the out-of-plane channel. Only in the superconducting films did the spectra show evidence of coherent dz2-pz-dz2 hybridization, meaning that the dz2 orbitals on nickel atoms in adjacent layers, linked through the apical oxygen pz orbitals, merge into well-defined bonding and antibonding bands that straddle the bilayer. In the insulating and metallic samples, this interlayer coherence is absent or incoherent, and the two layers effectively fail to form a unified electronic entity.

The magnetic data reinforce the same conclusion. In the non-superconducting samples, static spin-density-wave order is prominent, indicating that electrons are locked into a periodic magnetic texture that gaps out parts of the Fermi surface and suppresses coherent metallic behavior. As the samples move into the superconducting regime, this static spin order is suppressed, and the spin excitations measured by RIXS become strongly damped, their spectral weight broadening and softening in a manner reminiscent of the paramagnons observed in cuprate superconductors. The coexistence of coherent interlayer hybridization, suppressed static magnetism and heavily damped but persistent spin fluctuations defines the narrow window in which superconductivity emerges, suggesting that magnetic fluctuations surviving the collapse of long-range order may still contribute to the pairing interaction.

Perhaps the most practically important finding concerns the tuning knobs that control the interlayer channel. The researchers found that both oxygen stoichiometry and epitaxial strain, the mechanical distortion imposed on the film by the underlying substrate, directly modulate the strength of the dz2-pz-dz2 hybridization. Oxygen vacancies disrupt the apical oxygen network that mediates the interlayer hopping, while strain alters the geometry of the octahedra and the spacing between layers. Because both parameters tune the same orbital channel, superconductivity in bilayer nickelates occupies only a narrow regime of interlayer coherence, explaining why samples grown or treated slightly differently can show wildly different transport behavior. This insight offers a concrete design rule for future experiments: optimize the apical oxygen environment and the interlayer spacing, and the superconducting fraction and transition temperature should follow.

The broader significance of this work lies in how it positions the nickelates relative to the cuprates. In cuprate superconductors, superconductivity is widely understood through a single-band picture in which doped holes in the dx2-y2 orbital pair through antiferromagnetic fluctuations, with the famous Zhang-Rice singlet capturing the essential physics. The bilayer nickelates refuse to fit into that framework. Their superconductivity requires simultaneous coherence in two orbital channels, an in-plane itinerant channel and an out-of-plane hybridized channel, making them genuinely multiorbital superconductors. This complexity is not a nuisance but an opportunity, because it adds new adjustable degrees of freedom, orbital occupancy, interlayer hopping and Hund’s rule coupling, that have no direct analogue in the cuprates and could in principle be exploited to push transition temperatures higher.

The path forward is now well marked. Thin film growth, already proven capable of ambient-pressure superconductivity in these materials, provides the platform for systematic strain engineering, while oxygen recycling protocols allow fine control of the apical oxygen network. Spectroscopists can now interrogate genuine superconducting samples rather than inferring properties from non-superconducting relatives, and the identification of coherent interlayer hybridization as the superconducting enabler gives theorists a sharp target for microscopic models of the pairing mechanism. If the nickelates continue to follow the trajectory that this study illuminates, the dream of a new family of high-temperature superconductors, one built not on a single orbital but on the quantum coupling of paired atomic planes, looks increasingly within reach.

Subject of Research: The role of interlayer orbital hybridization in superconductivity of bilayer nickelate thin films

Article Title: Interlayer hybridization promotes superconductivity in bilayer nickelates

Article References: Zhang, S., Zhang, M., Luo, Q., Tao, Z., Huang, H.-Y., Weschke, E., Li, K., Channagowdra, G., Li, J., Fu, J., Huang, D.-J., Xie, Y., Lu, Y., & Peng, Y. (2026). Interlayer hybridization promotes superconductivity in bilayer nickelates. Nature Materials. https://doi.org/10.1038/s41563-026-02750-z

Image Credits: AI Generated

DOI: 10.1038/s41563-026-02750-z

Keywords: bilayer nickelates, superconductivity, interlayer hybridization, dz2 orbital, resonant inelastic X-ray scattering, X-ray absorption spectroscopy, spin-density wave, thin films, oxygen stoichiometry, epitaxial strain, multiorbital physics, cuprates

The new work arrives at a moment when CO2 electroreduction stands at a crossroads. Laboratory demonstrations of copper-based catalysts converting carbon dioxide into ethylene, ethanol and other multicarbon products have multiplied rapidly over the past decade, but translating those results into industrial electrolyzers capable of gigatonne-scale operation demands catalysts that remain active, selective and stable for thousands of hours. Catalyst reconstruction sits at the heart of that challenge. When a copper catalyst reorganizes itself under operating conditions, its activity can rise or fall, its product selectivity can drift toward desired chemicals or toward wasteful hydrogen evolution, and its lifetime can be cut dramatically short. Until now, the field has lacked a standardized, reproducible methodology for investigating these transformations—leaving individual laboratories to improvise their own approaches, with results that are often difficult to compare or reproduce.

The protocol is organized around what the authors call a ‘reconstruction–understanding–intervention’ workflow, a modular pipeline that guides researchers from the first observation of structural change all the way to deliberate control of the catalyst’s final state. The first stage involves the identification and taxonomy of reconstruction phenomena, classifying the many ways a copper surface can transform: morphological reshaping, chemical state changes such as the reduction of copper oxides to metallic copper or the persistence of transient copper(I) species, and compositional evolution in alloyed or bimetallic systems. By establishing a common vocabulary and systematic identification procedures, the protocol addresses one of the field’s most persistent problems—different groups describing fundamentally different phenomena under the same broad label of ‘reconstruction’.

The second stage tackles the question of what drives these transformations in the first place. Reconstruction is governed by an interplay of electrochemical and environmental factors: applied potential, local pH, the identity and concentration of electrolyte cations and anions, mass transport of CO2 to the surface, and the adsorption of reaction intermediates such as carbon monoxide. The protocol lays out quantitative methods for disentangling these variables, allowing researchers to determine whether a particular restructuring event is triggered by potential cycling, by the accumulation of hydroxyl species, by the migration of alkali metal cations into the interfacial layer, or by some combination of influences. This quantitative grounding is essential, because interventions can only be rationally designed once the governing factors are known.

At the technical core of the protocol lies a battery of complementary in situ and operando characterization techniques, each chosen to illuminate a different aspect of the catalyst’s evolving structure. Operando Raman spectroscopy tracks surface oxides, adsorbed intermediates and the formation of species such as copper carbonyl in real time under working conditions. Infrared spectroscopy, including surface-enhanced variants based on attenuated total reflection, probes the vibrational fingerprints of adsorbed molecules and interfacial water networks. X-ray absorption spectroscopy, typically performed at synchrotron facilities, reveals changes in the oxidation state and local coordination environment of copper atoms deep within the working electrode. Quasi-in situ X-ray photoelectron spectroscopy bridges the gap between fully operando measurements and conventional ex situ analysis: the protocol describes a compact titanium-alloy transfer cell, sized to pass through a glovebox antechamber, that allows electrodes to be interrogated at defined electrochemical states without exposure to air, preserving chemical information that would otherwise be lost.

The methodological rigor extends to the hardware itself. The protocol provides detailed descriptions of electrochemical cell configurations—flow cells, gas diffusion electrode assemblies and spectroscopy-compatible electrolytic cells—because the authors emphasize that the very design of the cell influences how catalysts reconstruct. Extended data accompanying the article specify, for example, the geometry of an operando Raman flow cell built from polyetheretherketone with a titanium flow field and quartz optical window, and the configuration of an operando XAS cell sealed with Kapton film and oriented at 45 degrees to the incident X-ray beam. Standardizing these details means that structural dynamics observed in one laboratory can be meaningfully compared with results from another, a prerequisite for building a reliable, field-wide picture of copper’s behavior under reaction conditions.

With identification and diagnosis in hand, the protocol’s third pillar moves into territory that sets it apart: active intervention. Rather than treating reconstruction as an inevitable degradation process to be tolerated, the authors present three primary strategies for steering it toward desired active states. The first is catalyst structure modulation, in which the starting material—its composition, oxide content, strain and dopant profile—is engineered so that the reconstruction pathway terminates at a favorable configuration. The second is electrochemical operation regulation, including pulsed or intermittent electrolysis protocols that periodically reset or regenerate the catalyst surface. The third is reaction microenvironment management, in which the electrolyte composition, local hydrophobicity, cation distribution and interfacial water structure are tuned to stabilize particular surface states and suppress destructive pathways.

The methodology was validated across representative classes of copper catalysts, demonstrating its breadth. Commercial metallic copper foil, oxide-derived copper—the family of catalysts in which pre-formed oxides reorganize during reaction to create highly active surfaces—and bimetallic copper-based systems denoted Cu–X, where a second metal tunes copper’s electronic structure, all serve as test cases. In each case, the workflow linked specific reconstruction dynamics to catalytic behavior and showed that deliberate control strategies enhanced both performance and stability of CO2 reduction. The validation examples map onto the team’s own published record, including work on oxophilicity-controlled multicarbon alcohol production over Lewis-acid-doped copper, lanthanide-induced tensile-strained copper oxide catalysts, acid-fed lanthanum–copper spheres operating at ampere-level currents, in situ periodic regeneration of catalysts, and self-adaptive catalysts for CO2 electroreduction.

The broader significance of the protocol extends well beyond copper. The authors explicitly frame the workflow as an adaptable framework for investigating dynamic surface evolution in other electrocatalytic reactions, from nitrate reduction to ammonia—where correlated operando microscopy and spectroscopy have similarly revealed restructuring—to carbon monoxide reduction and beyond. As the global push toward carbon neutrality intensifies, the ability to design ‘self-adaptive’ electrocatalysts that respond constructively to their operating environment, rather than degrading under it, is emerging as a defining goal of the field. By providing a reproducible, modular and quantitative path from observation to mechanistic insight to rational control, this protocol gives the community a shared toolkit for reaching that goal. In effect, it transforms one of electrocatalysis’s most stubborn complications into an engineering variable—one that can be measured, modeled and ultimately mastered in the service of converting waste carbon dioxide into the fuels and chemicals of a sustainable economy.

The scientific backdrop to this protocol is a decade of discoveries that progressively dismantled the assumption of a static copper surface. Operando studies have shown that metallic copper can fragment into active nanograins under reaction conditions, while solution-based transient copper(I) species have been identified as mediators of surface reconstruction. Other work has revealed that oxygen trapped within oxide-derived copper can diffuse and persist during catalysis, and that hydroxyl radicals play a decisive role in reoxidizing reduced copper surfaces. Adsorbed hydroxide itself has been described as a double-edged sword, simultaneously promoting carbon–carbon coupling and destabilizing the catalyst. Each of these findings underscores why a single snapshot of a catalyst before or after electrolysis is insufficient: the active state may exist only transiently, sandwiched between structural configurations that are themselves catalytically inert.

The protocol also responds to a subtler problem: the observation itself can depend on how it is made. Recent comparative studies have demonstrated that cell configuration measurably alters how copper reconstructs, since flow geometry, electrolyte layer thickness and local mass transfer shape the interfacial chemical environment. Operando X-ray absorption work has quantified these mass-transfer effects directly, showing that concentration gradients near the electrode influence both the reaction pathway and the structural evolution of the catalyst. By specifying standardized cell geometries and measurement procedures, the protocol helps ensure that apparent differences between catalysts reflect genuine materials behavior rather than apparatus artifacts.

Another theme the protocol consolidates is the mechanistic link between reconstruction and selectivity. Spectroscopic observations of carbon monoxide bridge species forming on dynamically restructured copper, together with reconstruction-dependent coordination descriptors, suggest that the evolving surface geometry directly tunes how intermediates bind and couple. This reframes selectivity in CO2 electrolysis as a property of a moving target. The practical consequence is that stability and performance can no longer be optimized independently; a protocol that treats the catalyst’s trajectory through time as the design object, rather than its initial composition, aligns catalyst development with how these materials actually behave in operating electrolyzers.

Subject of Research: Dynamic reconstruction of copper-based catalysts during electrochemical CO2 reduction and methods for probing and controlling it

Article Title: Probing and controlling Cu catalyst reconstruction during CO2 electroreduction

Article References: Zhang, L., Zheng, C., Xu, L., Feng, J., Jia, S., Wu, L., Song, X., Zhang, M.-D., Wang, R., Zhang, X., Zhao, Z., Sun, X., & Han, B. (2026). Probing and controlling Cu catalyst reconstruction during CO2 electroreduction. Nature Protocols. https://doi.org/10.1038/s41596-026-01430-1

Image Credits: AI Generated

DOI: 10.1038/s41596-026-01430-1

Keywords: CO2 electroreduction, copper catalyst, catalyst reconstruction, electrocatalysis, operando spectroscopy, Raman spectroscopy, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, multicarbon products, catalyst stability, oxide-derived copper, carbon neutrality