Atomic-Scale Tag Team: Ordered Metal Pairs Crack the Code for Clean Urea Production

Urea is one of the most consequential molecules in modern civilization. It feeds roughly half the world’s population as the backbone of nitrogen fertilizer, and it underpins industries from resins and adhesives to diesel exhaust treatment. Yet nearly all of it is still made the way it has been for a century: ammonia synthesized under the punishing conditions of the Haber–Bosch process is combined with carbon dioxide at high temperatures and pressures in energy-hungry plants. Now a team of Chinese researchers has demonstrated a strikingly different approach, one that welds carbon and nitrogen together at room temperature in an electrochemical cell, using a precisely ordered alloy whose atomic architecture acts like a molecular assembly line. The work, published in Nature Synthesis, reports a copper–gold–zinc intermetallic catalyst that converts carbon dioxide and nitrate into urea with efficiencies and durability that push the field closer to practical, decentralized chemical manufacturing.

The central obstacle in electrochemical urea synthesis has never been a lack of possible reactions but a stubborn mismatch of timing. To build the carbon–nitrogen bond at the heart of urea, a catalyst must simultaneously reduce two very different feedstocks: carbon dioxide, which needs to be transformed into a carbon-containing intermediate such as *COOH or carbon monoxide, and nitrate, which must be stripped of oxygen and hydrogenated toward nitrogen-containing species like *NH2. These two reaction cascades proceed at different rates and prefer different potentials, so on most catalysts the intermediates simply never coexist on the surface long enough, or close enough, to couple. Instead, the cell churns out side products, typically ammonia from nitrate reduction or carbon monoxide and hydrogen from competing reactions, and the desired C–N coupling is left as a minor footnote in the product distribution.

The researchers, led by Yongwen Tan of Hunan University with co-first authors Jiao Lan and Zhiwen Chen, attacked this kinetic mismatch with a design philosophy built on what they call dual atomic pairs. Rather than scattering catalytic functions randomly across a surface, they engineered an atomically ordered CuAuZn2 intermetallic compound, a crystalline solid in which copper, gold, and zinc atoms occupy fixed, alternating lattice positions. That order is the crucial ingredient. In an ordinary alloy, atoms mix in a more or less statistical fashion, so the local environment of any given site is unpredictable. In an intermetallic, by contrast, the crystal structure guarantees that specific pairs of neighboring atoms appear at high density and in a repeating, deterministic pattern. The team’s material therefore presents dense arrays of Cu–Zn pairs sitting alongside dense arrays of Au–Zn pairs, each with its own catalytic specialty.

The division of labor is elegant. Spectroscopic and computational analyses described in the paper indicate that the Cu–Zn sites are tuned to drive nitrate reduction efficiently, guiding the six-electron-plus-six-proton transformation all the way to the *NH2 intermediate rather than letting it run to completion as ammonia. Neighboring Au–Zn sites, meanwhile, excel at the first step of carbon dioxide reduction, generating the *COOH intermediate that supplies the carbon partner. Because these two site types are atomically interspersed throughout the ordered lattice, the nitrogen and carbon intermediates are produced in immediate proximity, at matched rates, dramatically raising the probability that they will couple into a C–N bond before drifting away or over-reducing. It is a tandem catalysis concept executed not at the scale of particles or domains but at the scale of individual atoms, enforced by crystallography itself.

The performance numbers reported for the ordered CuAuZn2 electrode are remarkable by the standards of this young field. Under co-reduction of carbon dioxide and nitrate at zero volts versus the reversible hydrogen electrode, a potential so mild it sits near the thermodynamic neutral point for the combined reaction, the catalyst achieved a Faradaic efficiency of 85.5 percent, plus or minus 1.6 percent, meaning that fraction of the electrical current went into making urea rather than waste products. The energy efficiency reached 50.1 percent, plus or minus 1.5 percent, a figure that matters enormously for any future industrial deployment, since electricity is the dominant operating cost of electrosynthesis. For a reaction that stitches together two small molecules through a multi-electron cascade, delivering half of the input energy into the target product is a benchmark few competing systems have approached.

Durability, often the Achilles heel of designer electrocatalysts, received equally serious attention. The team moved beyond the small laboratory beakers typical of early-stage studies and built a membrane electrode assembly, the compact device architecture used in commercial electrolyzers and fuel cells. In that demanding configuration, the ordered intermetallic catalyst operated continuously for 1,000 hours at a current density of 100 milliamperes per square centimeter, sustaining a urea production rate of approximately 8.3 milligrams per hour per square centimeter of electrode. A thousand hours of stable operation at ampere-scale current densities is the kind of stress test that separates laboratory curiosities from technology candidates, and the fact that the atomically ordered structure survived it suggests the intermetallic lattice is genuinely robust under operating conditions rather than a fleeting surface reconstruction.

The structural characterization underpinning these claims drew on a comprehensive toolkit. X-ray absorption spectroscopy, including analysis of the fine structure near the absorption edges of each metal, was used to confirm the local coordination environments of copper, gold, and zinc and to verify that the atoms occupy their ordered lattice sites rather than segregating. Electron microscopy and diffraction methods documented the morphology and crystalline phase of the material, which the authors describe as a nanoporous form of the intermetallic with isolated single-atom alloy characteristics. The nanoporous architecture is not merely cosmetic: it multiplies the electrochemically active surface area and ensures that the high-density dual atomic pairs built into the bulk crystal are actually exposed to the electrolyte where the reaction happens.

Mechanistic experiments and density functional theory calculations, presented in the study’s fifth figure, flesh out the picture of how the C–N bond forms on this surface. The computational work supports the assigned roles of the two site types, showing that the energetics of nitrate-to-*NH2 conversion are favorable on Cu–Zn ensembles while CO2-to-*COOH conversion is favored on Au–Zn ensembles, and that the coupling step itself benefits from the co-location of the two intermediates. In situ spectroscopy tracked the reaction as it proceeded, providing experimental corroboration for the intermediates identified computationally. Together, the evidence paints a coherent mechanistic narrative in which the ordered lattice functions as a nanoscale reaction vessel with two complementary active sites working in concert, resolving the kinetic mismatch that has plagued the field.

The broader implications extend well beyond urea itself. The authors note that the dual atomic pair concept can be extended to other carbon–nitrogen coupling reactions and, more generally, to the electrosynthesis of high-value amides, a chemical class that includes pharmaceuticals, agrochemicals, and commodity materials. If the design principle holds, it offers a general recipe for multi-intermediate catalysis: choose an ordered intermetallic whose lattice positions place different metal pairs in fixed adjacency, assign each pair a half-reaction, and let crystallographic order guarantee the spatial coordination that random alloys cannot. The team’s earlier work on ordered Cu–Zn intermetallics for nitrite-to-ammonia conversion, also published in Nature Communications, suggests this is a deliberate, evolving research program rather than a one-off discovery.

There are, of course, familiar caveats on the road from bench to plant. Gold is expensive, and any commercial catalyst would need to minimize its loading or find cheaper substitutes that preserve the same electronic structure. Nitrate feedstock, while abundant in agricultural runoff and industrial wastewater, would need reliable supply chains for a distributed manufacturing model, though that very abundance is part of the appeal, since the process could in principle turn a pollutant into fertilizer. Scale-up of membrane electrode assembly devices for this chemistry remains largely unexplored territory. Still, the combination of near-zero overpotential, record-setting efficiency, and thousand-hour stability makes this ordered intermetallic one of the most compelling demonstrations yet that electricity, water, carbon dioxide, and nitrate can be woven directly into the molecules that feed the world, one precisely placed atom pair at a time.

Subject of Research: Atomically ordered CuAuZn2 intermetallic catalysts with dual atomic pairs for electrochemical urea synthesis from carbon dioxide and nitrate

Article Title: Atomically ordered dual atomic pairs in CuAuZn2 intermetallics for efficient urea electrosynthesis

Article References: Atomically ordered dual atomic pairs in CuAuZn2 intermetallics for efficient urea electrosynthesis. (n.d.). https://doi.org/10.1038/s44160-026-01187-1

Image Credits: AI Generated

DOI: 10.1038/s44160-026-01187-1

Keywords: urea electrosynthesis, CuAuZn2 intermetallic, dual atomic pairs, C–N coupling, CO2 reduction, nitrate reduction, electrocatalysis, Faradaic efficiency, membrane electrode assembly, sustainable fertilizer, tandem catalysis, Nature Synthesis