The core insight concerns a mechanism that electrochemists have courted for a decade: lattice-oxygen redox. In conventional metal oxide and oxyhydroxide catalysts, oxygen atoms in the crystal framework sit passively as spectators; every bond made and broken during water oxidation happens at adsorbed intermediates such as *OH and *O. That is safe but slow, because the adsorption energies of these intermediates are locked together by rigid scaling relationships. Make *OH binding stronger to speed up one step, and *O binding strengthens too, penalizing another. The scaling relations impose a theoretical floor on the overpotential, a tax every conventional catalyst must pay. Lattice-oxygen redox breaks that tax. When framework oxygen atoms themselves participate in the redox chemistry, oxygen-oxygen bonds can form through direct coupling of lattice oxygen, sidestepping the adsorbate scaling conundrum entirely.

The catch is stability, and it has been brutal. Oxidizing lattice oxygen means ripping electrons from the very orbitals that hold the crystal together. Once activated indiscriminately, that oxidation delocalizes across the lattice, holes accumulate on framework oxygen, metal-oxygen bonds soften and break, and the material dissolves or amorphizes. Many catalysts that unlock lattice oxygen in the laboratory die within hours under the punishing polarization of a real electrolyzer. The literature is littered with tantalizing activity reports that collapse under accelerated ageing. The Singapore-led team, whose senior authors include Junmin Xue, Haoyin Zhong, Bin Tian and Xiaopeng Wang, asked a different question: what if lattice oxygen could be activated not all at once, but in a spatially ordered, electronically programmed sequence?

Their answer begins with an unlikely precursor: a composite of chromium(III) oxide and nickel diselenide, Cr2O3/NiSe2. When the electrode is held under anodic polarization in alkaline electrolyte, the reconstruction unfolds in two chemically distinct stages, and the order matters enormously. In the first stage, selenium leaches out of the NiSe2 phase. Losing the chalcogen opens up the nickel 3d band manifold, specifically broadening the antibonding eg band, the orbital set that overlaps with oxygen 2p states. A broader eg band strengthens nickel-oxygen covalency, and stronger covalency does two things at once: it accelerates the deprotonation of *OH intermediates, a known rate-limiting step on nickel oxyhydroxide surfaces, and it begins to tilt the electronic structure toward oxygen participation.

Then comes the second, decisive stage. Chromium begins to leach from the oxide component, and crucially, the chromium departure selectively depletes oxygen atoms that were coordinated to nickel across the composite interface. What remains is a modified nickel oxyhydroxide, SRA-NiOOH, in which oxygen non-bonding states, oxygen 2p orbitals stripped of their bonding partners, are generated not randomly across the lattice but in spatially confined pockets. This is the heart of the strategy. Confined non-bonding states act as local redox reservoirs for lattice oxygen, close enough to the surface to join the catalytic cycle, yet electronically quarantined so that oxidation holes cannot wander freely through the framework. Destructive redox delocalization, the killer mechanism of lattice-oxygen catalysts, is suppressed by construction. The oxygen-redox activity and the lattice stability, usually two ends of a seesaw, are decoupled.

The experimental evidence for this picture is layered across multiple structural and spectroscopic probes. X-ray absorption spectroscopy traces the changes in nickel coordination and oxidation state as reconstruction proceeds, while synchrotron-based measurements carried out at the Singapore Synchrotron Light Source document the emergence of the modified oxyhydroxide phase. Density functional theory calculations, performed with the ASTAR Computational Resource Centre and the National Supercomputing Centre in Singapore, complement the experiments, showing how the broadened eg* band and the confined oxygen non-bonding states reshape the energy landscape of the oxygen evolution mechanism. The team further demonstrates that the approach generalizes: the sequential-reconstruction activation paradigm is not a one-off trick of one composition but a design framework that can be exported to related systems, a claim their fourth figure addresses directly.

The device-level performance is where the work will command the most attention. Anion-exchange-membrane water electrolyzers are the commercial sweet spot for many of these nickel-based catalysts, because AEM technology can use earth-abundant transition metals instead of the iridium that proton-exchange-membrane electrolyzers demand. But AEM electrolyzers still need to run at high current density, above 2 amperes per square centimeter, to reach the cost targets that would make green hydrogen competitive with fossil-derived hydrogen. At 4.1 A cm-2 at 1.8 V in 1 M KOH at 80 degrees Celsius, the SRA-NiOOH anode sits squarely in industrially relevant territory, and the nearly 3,500-hour stability test under accelerated ageing at 60 degrees Celsius suggests the catalyst does not merely sprint; it runs a marathon. Sustained oxygen-redox operation at high current density, the authors argue, is precisely what the sequential electronic reconstruction buys: a durable oxygen-redox window that stays open under demanding polarization.

The conceptual contribution may outlast the specific numbers. For years, the field has treated catalyst reconstruction as something to minimize, a necessary evil on the path to stable operation, or at best a one-shot activation. This work reframes reconstruction as something to choreograph. By choosing a precursor whose constituents leach in a controlled order, selenium first, chromium second, the researchers wrote the electronic structure of the final catalyst as a timed sequence rather than a static composition. Each leaching event performed a specific electronic function, band broadening here, oxygen non-bonding state generation there, and the final NiOOH inherited the benefits of both without the instability that an uncontrolled surface transformation would bring. It is a programming philosophy applied to surfaces, and it echoes a broader shift in electrocatalysis toward operando-informed precatalyst design, in which the working electrode is understood as a dynamic, self-assembling entity rather than a fixed material.

There are, of course, caveats and open questions. The reported metrics come from laboratory-scale AEM cells and accelerated ageing protocols, and the road from such benchmarks to kilowatt-scale stacks involves membrane durability, flow uniformity, and cost questions that no single anode catalyst can answer alone. The precise atomic-scale geography of the confined non-bonding states, and how far the confinement holds as reconstruction continues over thousands of hours, will reward further study. But the bar the paper clears is a meaningful one: it shows that the activity-stability trade-off, long treated as a law of nature for lattice-oxygen catalysis, can be suspended by electronic design. If sequential reconstruction proves as general as the authors suggest, the oxygen evolution bottleneck that has constrained green hydrogen may finally have an engineering-grade exit, built not from a miracle material but from a catalyst taught to rebuild itself in the right order.

Subject of Research: Sequential electronic reconstruction of a Cr2O3/NiSe2 precursor to enable durable lattice-oxygen redox in anion-exchange-membrane water electrolysis

Article Title: Sequential electronic reconstruction enables durable oxygen redox in water electrolysis

Article References: Yu, J., Zhong, H., Zhang, Q., Zhang, X., Ye, Y., Diao, C., Yu, Z. G., Xi, S., Tian, B., Wang, X., & Xue, J. (2026). Sequential electronic reconstruction enables durable oxygen redox in water electrolysis. Nature Sustainability. https://doi.org/10.1038/s41893-026-01940-6

Image Credits: AI Generated

DOI: 10.1038/s41893-026-01940-6

Keywords: water electrolysis, oxygen evolution reaction, lattice oxygen redox, nickel oxyhydroxide, green hydrogen, anion-exchange membrane, electrocatalysis, catalyst reconstruction, eg band, catalyst stability, nickel selenide, Nature Sustainability

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