Ammonia is one of the world’s most important industrial chemicals. It is essential for fertilizer manufacturing, serves as a feedstock for numerous nitrogen-containing compounds, and is increasingly being considered as a hydrogen carrier and potential zero-carbon energy vector. Most ammonia is currently produced through the Haber–Bosch process, in which nitrogen and hydrogen react over catalysts at temperatures of roughly 400–500 °C and pressures of 15–25 megapascals. Although highly effective at large scale, the process consumes substantial energy and requires heavy infrastructure. The new approach replaces much of the thermal input with highly concentrated, nonequilibrium energy delivered by an electron beam.

In the reported system, a 2.0-megaelectronvolt beam passes through a gas-phase mixture of nitrogen and hydrogen. Rather than heating the entire reactor, the electrons transfer energy directly to molecules through collisions. These interactions can ionize or electronically excite nitrogen and hydrogen, producing radicals, ions, and secondary electrons that participate in subsequent reactions. The process is particularly significant because nitrogen’s triple bond is among the strongest chemical bonds found in common molecules. Breaking or substantially weakening that bond is the central challenge in converting atmospheric nitrogen into useful compounds.

The experiments showed that the hydrogen concentration strongly influenced ammonia formation. In the catalyst-free reactor, a mixture containing approximately 20 percent hydrogen provided the best performance, reaching an ammonia production rate of 0.14 micromoles per liter per second. Hydrogen appears to serve not only as the source of hydrogen atoms needed to form NH₃ but also as a chemical reducing agent. However, adding too much hydrogen reduced the efficiency of nitrogen activation, apparently because hydrogen molecules absorbed part of the available electron-beam energy and diverted reactive collisions away from nitrogen.

The researchers used multiscale Monte Carlo simulations involving Geant4-DNA, FLUKA, and TOPAS to investigate what happens after the primary electrons enter the gas. The calculations indicate that the incoming MeV electrons generate cascades of lower-energy secondary electrons. These secondary particles, rather than the original high-energy electrons alone, appear to be the most important agents in activating nitrogen. In particular, secondary electrons with energies between approximately 150 and 250 electronvolts were especially effective at inducing nitrogen ionization and excitation. The findings connect energy deposition at the reactor scale with molecular events occurring on nanometer scales.

This mechanism offers a different way of thinking about high-energy radiation chemistry. The primary electron beam functions as an energy-delivery tool, while the chemically active species are produced through a cascade of collisions. Excited nitrogen molecules and nitrogen-containing ions can undergo dissociation and reaction with hydrogen-derived radicals, eventually forming ammonia. In the gas phase, calculations suggested that recombination between nitrogen and hydrogen radicals is a thermodynamically favorable route. The result is a reaction network driven not by equilibrium heating but by a continuous supply of energetic electrons and short-lived reactive intermediates.

The team also tested carbon-supported ruthenium nanoparticles, a catalyst widely associated with nitrogen activation. Introducing the Ru/C material increased ammonia production by as much as 2.8 times compared with the catalyst-free system. The catalyst changed the optimum hydrogen concentration from 20 percent to approximately 50 percent, corresponding to the stoichiometric ratio required to combine one nitrogen molecule with three hydrogen molecules. This shift suggests that the ruthenium surface can capture and organize reactive species that would otherwise undergo random gas-phase collisions.

According to the researchers, electron irradiation also altered the electronic state of the ruthenium surface, making it more electron-rich. That change may facilitate nitrogen adsorption and activation. Density functional theory calculations indicated that nitrogen dissociation on the ruthenium surface has an energy barrier approximately 32.7 kilocalories per mole lower than the corresponding gas-phase process. Once nitrogen is activated on the surface, stepwise hydrogenation through NH and NH₂ intermediates becomes increasingly favorable, ultimately yielding ammonia. In this model, the catalyst acts as an energy ladder, lowering the barriers between successive reaction stages.

Isotope-labeling experiments provided an additional check on the reaction’s origin. When the researchers used nitrogen-15 and deuterium instead of ordinary nitrogen and hydrogen, the labeled atoms appeared in the ammonia products. This evidence confirmed that the detected ammonia came from the supplied N₂ and H₂ rather than from contamination in the surrounding environment or reactor components. The results establish a proof of concept for electron-beam-driven ammonia synthesis under mild conditions, although the reported production rate and energy requirements will need further improvement before the technology can compete with established industrial systems.

The researchers envision future reactors that optimize electron energy deposition, gas flow, catalyst placement, and continuous operation. Because electron beams can be powered by electricity, the approach could potentially be coupled with renewable energy and adapted to smaller, distributed ammonia plants. Its practical value will depend on improving energy efficiency, beam utilization, reactor durability, product separation, and scale-up economics. Even so, the study demonstrates that a high-energy electron beam can transform a difficult bond-breaking problem into a controllable cascade of molecular events, opening a new avenue for low-temperature nitrogen fixation and electrically driven chemical manufacturing.

Subject of Research: Experimental study

Article Title: Ambient Ammonia Production from Nitrogen and Hydrogen Gases Enabled by Dissociative High-Energy Electron Impact Interactions

News Publication Date: 3-Jul-2026

Web References: CCS Chemistry, https://www.chinesechemsoc.org/journal/ccschem; DOI: 10.31635/ccschem.026.202607688

References: DOI: 10.31635/ccschem.026.202607688

Image Credits: CCS Chemistry

Keywords

Ammonia synthesis, nitrogen fixation, hydrogen, high-energy electron beam, radiation chemistry, secondary electrons, ruthenium catalyst, green chemistry, renewable energy, Haber–Bosch alternative

Researchers led by Professor Yousung Jung at Seoul National University have proposed a catalyst-design principle that selectively suppresses hydrogen evolution while preserving the electrochemical reaction that converts nitrogen into ammonia. Their approach relies not on removing protons from the reaction environment, but on controlling how easily those protons can physically reach the electrode surface. The concept could offer a new route toward cleaner ammonia production powered by renewable electricity.

Ammonia is increasingly viewed as a practical carrier for hydrogen energy. It stores a large amount of hydrogen, remains liquid at room temperature under moderate conditions, and is easier to transport than gaseous hydrogen. Today, most ammonia is manufactured through the Haber–Bosch process, which requires high temperatures and pressures and consumes substantial amounts of energy. Because the process is commonly powered by fossil fuels, it also produces significant carbon dioxide emissions.

Electrochemical nitrogen reduction has emerged as a possible alternative. In principle, the process uses nitrogen, water and electricity to produce ammonia, potentially allowing production facilities to operate near wind or solar farms rather than relying on massive centralized chemical plants. The central obstacle, however, is that the electrode preferentially produces hydrogen instead of ammonia. This competing hydrogen evolution reaction consumes electrons and protons that would otherwise contribute to nitrogen reduction, sharply reducing ammonia yields.

Previous strategies have often attempted to control hydrogen evolution by changing the proton concentration or acidity of the electrolyte. That solution creates a fundamental trade-off: protons are needed not only to generate hydrogen but also to convert nitrogen into ammonia. Reducing their availability can therefore suppress both reactions. Jung’s team instead focused on the reaction interface—the narrow region where the electrolyte, catalyst and electrode meet—and asked whether the two reactions could be separated geometrically.

The researchers designed a reaction environment in which proton donors encounter greater steric hindrance as they approach the electrode surface. Steric hindrance occurs when the size and arrangement of molecules make it physically difficult for another molecule to reach a reactive site. In this case, the researchers effectively create a molecular gate around the electrode. Proton donors can still exist in the surrounding solution, but their paths toward the surface become restricted, making the initial step of hydrogen production less favorable.

That initial step is known as the Volmer reaction. During the Volmer reaction, a proton receives an electron and forms an adsorbed hydrogen atom on the electrode. Two such hydrogen atoms can subsequently combine to form molecular hydrogen, or an adsorbed hydrogen atom can react with another proton and electron. By making it harder for proton donors to reach the electrode, the new strategy raises the energy barrier for the Volmer reaction and slows the entire hydrogen evolution pathway.

The geometry of nitrogen reduction is different. According to the researchers, nitrogen molecules protrude outward from the catalyst environment, allowing protons to interact with nitrogen rather than needing to reach the electrode surface directly. This difference means that the same steric barrier that obstructs hydrogen evolution has a much smaller effect on nitrogen reduction. The result is a form of molecular selectivity based on access and positioning rather than solely on chemical composition.

The team used microkinetic modeling to examine how these competing pathways respond to changes in steric hindrance and applied voltage. Microkinetic models describe the rates of individual elementary reactions by tracking intermediates and solving differential equations for the overall reaction network. The simulations indicated that increasing steric hindrance can maintain high Faradaic efficiency across a broad voltage range. Faradaic efficiency measures the fraction of supplied electrical charge that produces the desired product—in this case, ammonia rather than hydrogen.

The findings could address a major limitation in electrochemical ammonia research, where Faradaic efficiencies have often remained near 70 percent or lower. The researchers report that their design principle could raise the value toward nearly 100 percent under modeled conditions, although future catalyst development and experimental validation will be essential. The strategy may also be transferable to other electrochemical systems in which a desired reaction competes with an unwanted one, including carbon dioxide reduction.

The study, published in the Journal of the American Chemical Society, presents the reaction interface itself as a programmable component of catalyst design. Rather than treating the electrolyte as a passive medium, the approach uses molecular shape to control which reactants can reach specific locations. Jung’s team plans to identify highly active catalyst materials that can incorporate this principle and to test the concept across additional reactions. If successful, the work could help bring renewable-powered ammonia production closer to practical use while offering a broader blueprint for controlling chemical reactions at the atomic scale.

Subject of Research: Electrochemical nitrogen reduction and selective suppression of the hydrogen evolution reaction

Article Title: Selective Suppression of Hydrogen Evolution in Electrochemical Nitrogen Reduction through Steric Control of Proton Donors

News Publication Date: July 22

Web References: https://doi.org/10.1021/jacs.6c07080

References: Journal of the American Chemical Society, DOI: 10.1021/jacs.6c07080

Image Credits: Seoul National University College of Engineering

Keywords

Electrochemical ammonia production, nitrogen reduction reaction, hydrogen evolution reaction, steric hindrance, catalyst design, green hydrogen, renewable energy, Faradaic efficiency, microkinetic modeling, Seoul National University

Ammonia (NH3) is a cornerstone of modern agriculture and industry, primarily synthesized through the Haber-Bosch process, which consumes vast amounts of energy and emits significant greenhouse gases due to its dependence on fossil fuels and high operating temperatures and pressures. The technology unveiled recently leverages a gliding arc discharge plasma reactor to convert nitrogen from ambient air into reactive nitrogen oxides (NOx), which serve as key intermediates for subsequent chemical transformations. By integrating this with a membrane electrode assembly capable of electrochemically reducing NOx species into ammonia, researchers have built a system operating efficiently at room temperature without the need for hydrogen from fossil fuels.

The heart of this system is the gliding arc discharge plasma reactor, which ionizes ambient air to generate a rich stream of NOx compounds. Unlike conventional reactors relying on pure nitrogen gas, this design exploits the ubiquity and cost-effectiveness of atmospheric air, dramatically simplifying the feedstock requirements while maintaining reaction efficiency. The plasma’s unique non-equilibrium conditions activate nitrogen molecules, breaking their strong triple bonds and enabling the formation of nitrogen oxides through complex ion-molecule reactions. This approach eliminates the energy-intensive nitrogen fixation steps typical of conventional ammonia synthesis.

Following NOx generation, the system channels these reactive species into a specialized electrochemical cell outfitted with a novel perovskite oxide catalyst—La₁.₅Sr₀.₅Ni₀.₅Fe₀.₅O₄. This catalyst exhibits remarkable stability under strongly acidic conditions and facilitates selective reduction of nitrite (NOₓ⁻) ions to ammonia. This acid-tolerant catalyst is a critical enabler of continuous operation, overcoming a long-standing challenge in nitrogen reduction reactions, where catalyst degradation commonly impedes long-term viability. The membrane electrode assembly design also ensures efficient ion transport and minimal energy loss, enhancing the system’s overall efficiency.

One of the standout features of this plasma-electrochemical nitrogen reduction reaction (PE-N₂RR) system is its scalability and adaptability. Beyond generating NOx directly from ambient air, the system can equally utilize NOx derived from industrial waste streams, such as flue gases from factories. This flexibility not only maximizes raw material sources but also offers a dual environmental benefit: transforming pollution into productive feedstock for valuable chemical synthesis. Such integration presents a promising circular economy model where waste products contribute to sustainable chemical processes.

The researchers emphasize that mastering the interplay between plasma generation parameters and electrochemical settings is vital to optimizing the system’s performance. Key operating conditions include plasma discharge power, gas flow rates, electrolyte composition, electrode materials, and cell configuration. Small adjustments in these parameters profoundly influence the NOx production rates, catalyst activity, and ammonia yield. The highly interdisciplinary nature of this work necessitates expertise spanning plasma physics, electrochemistry, and materials science to tailor and engineer each module for maximal output.

Synthesizing the La₁.₅Sr₀.₅Ni₀.₅Fe₀.₅O₄ perovskite catalyst itself is a carefully controlled process, involving solid-state reaction techniques scalable from laboratory to industrial quantities. Ensuring phase purity and optimal surface characteristics is crucial to achieving the desired catalytic properties. The reported protocol details synthesis steps, characterization methods, and handling procedures to maintain catalyst integrity, signaling a robust foundation for future deployment and commercialization.

Time investment for setting up the entire PE-N₂RR system is nontrivial but manageable, with the catalyst synthesis and assembly of plasma and electrochemical reactors estimated at around 72 hours. Comprehensive reaction testing to validate continuous operation extends to approximately 200 hours, during which system stability and productivity metrics are rigorously evaluated. Additional diagnostics, such as in situ electrochemical analyses, provide mechanistic insights and typically require around 3 hours, collectively facilitating thorough process understanding.

This approach represents a monumental stride toward decentralizing ammonia production from massive, centralized plants to distributed installations closer to agricultural sites or industrial consumers. By bypassing the high-pressure hydrogen step and utilizing abundant air and water, the system circumvents supply chain constraints and reduces the carbon emissions associated with ammonia manufacture. Such decentralization could empower local economies, reduce transportation emissions, and foster resilience in fertilizer supply chains, especially in developing regions.

The environmental ramifications extend beyond decarbonizing ammonia synthesis. Utilizing ambient air eliminates dependence on pure nitrogen sources, which often require energy-intensive separation processes. Moreover, harnessing atmospheric water as a proton source aligns with green chemistry principles. The potential substitution of plasma-generated NOx with industrial NOx waste further mitigates air pollution issues by converting toxic emissions into valuable chemical feedstocks, exemplifying the circularity inherent in the PE-N₂RR methodology.

Still, challenges remain to advance this technology from laboratory demonstration to broad real-world adoption. Scaling plasma reactors while maintaining energy efficiency, ensuring catalyst longevity beyond initial testing periods, and integrating the system within existing industrial frameworks require further research and engineering innovation. Additionally, economic models must validate the cost competitiveness relative to Haber-Bosch ammonia to incentivize adoption at scale.

Nevertheless, this plasma-electrochemical hybrid stands as a beacon of creativity and sustainability in chemical synthesis innovation. It leverages fundamental principles of plasma physics and electrochemistry, marrying them with advanced materials science to harness air and water—earth’s most accessible and abundant resources—for the efficient generation of a vital commodity chemical. The environmental, economic, and operational advantages portend transformative impacts across agriculture, energy, and chemical manufacturing sectors.

Experts hail this technology as a promising platform for broader nitrogen and oxygen chemical conversions beyond ammonia synthesis. The modularity and tunability of plasma and electrochemical cells enable exploration of other value-added nitrogen compounds, potentially opening new avenues for sustainable chemical production. The detailed procedural blueprint and analytical framework provided will catalyze further investigations and innovations in the field.

In an era marked by climate urgency and resource challenges, this plasma-coupled electrochemical ammonia synthesis protocol stands out as a powerful illustration of multidisciplinary ingenuity harnessing cutting-edge science for practical solutions. Its potential to decarbonize a fundamental chemical process, reduce dependency on fossil fuels, and create a circular resource economy encapsulates the tandem goals of environmental stewardship and technological advancement.

As the scientific community embraces and iterates on this approach, decentralized, sustainable ammonia production may soon shift from visionary concept to everyday reality, profoundly impacting food security, industrial chemistry, and our planet’s health. This emerging technology signals hope for a greener, more resilient chemical industry driven by novel plasma-electrochemical synergies and earth-abundant materials.

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Subject of Research: Sustainable ammonia synthesis through plasma-electrochemical nitrogen reduction.

Article Title: Plasma-coupled electrochemical ammonia synthesis from air and water under ambient conditions.

Article References:
Guo, X., Gao, Y., Zhang, C. et al. Plasma-coupled electrochemical ammonia synthesis from air and water under ambient conditions. Nat Protoc (2026). https://doi.org/10.1038/s41596-026-01332-2

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41596-026-01332-2