A burst of high-energy electrons has driven a reaction that normally demands extreme industrial conditions, producing ammonia from nitrogen and hydrogen gases at room temperature and atmospheric pressure. Researchers led by Professor Jun Ma at the University of Science and Technology of China report that a megavolt electron beam can activate the exceptionally stable nitrogen molecule and generate ammonia without an external heat source or conventional catalyst. The study, published in CCS Chemistry, presents a possible new route toward electrically powered, modular ammonia production.
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
