A team of researchers led by the University of Sydney has demonstrated a promising new route for green ammonia synthesis that mimics the power of lightning. By pairing atmospheric plasma with carefully engineered electrocatalysts, the study delivers ammonia from air and water at room temperature—no pressurized hydrogen, no high heat, and no fossil fuels. At the core of this innovation is a catalyst built from Fe₂O₃ nanoparticles supported on copper, offering a sustainable alternative to the century-old Haber–Bosch process. 

Their approach isn’t just a theoretical improvement—it offers real gains in energy efficiency, reaction stability, and product separation, with the potential to reshape how nitrogen fertilizer is produced at small and distributed scales. The process also supports broader goals in the transition to a hydrogen-based economy and carbon-free fuel production. 

Four nitrogen fixation routes (Cullen et al., 2025).

Rethinking Ammonia: From Haber–Bosch to Plasma Innovation 

For over a century, industrial ammonia synthesis has relied on the Haber–Bosch method. While highly effective at scale, the process demands high-purity nitrogen and hydrogen molecules, extreme operating conditions, and significant energy input—mostly derived from natural gas and other fossil fuels. As a result, it contributes notably to global energy consumption and climate change. 

Electrocatalytic nitrogen fixation, driven by renewable electricity, has emerged as a potential alternative. But the intrinsic inertness and low solubility of nitrogen molecules in water, along with competing side reactions, have restricted their efficiency and practicality. 

Nonthermal plasma systems offer an alternative route, activating oxygen and nitrogen molecules from ambient air to form nitrogen oxides (NOₓ) that can be electrochemically reduced. Plasma-electrochemical systems are, however, widely available in the liquid phase and result in hard-to-separate nitrate and ammonium ions, which, during post-processing, usually end up as lost ammonia. The use of membrane-based electrolyzers or water electrolysis in such systems can further complicate reactor design and scalability. 

This latest study introduces a more efficient and eco-friendly reactor system that produces gaseous ammonia in its gas form directly from air, minimizing downstream treatment and improving overall energy efficiency. 

Schematic diagram showing the process of plasma treatment, wet chemical impregnation and calcination (Cullen et al., 2025). 

The Fe₂O₃/Cu Catalyst at the Core of the Reaction 

This gas-phase plasma-electrochemical reactor features a well-designed catalyst at its core, composed of iron (III) oxide nanoparticles deposited on copper. All the materials play roles in the system's performance. 

Fe₂O₃, engineered with oxygen vacancies through plasma pretreatment and thermal calcination, provides active sites that enhance nitrogen oxide (NOₓ) adsorption and facilitate electron transfer. These defect-rich surfaces play a key role in stabilizing reactive intermediates and improving the kinetics of ammonia formation via the NHO pathway. 

Copper serves as both a conducting scaffold and a chemical reagent. It has dynamic redox interactions due to variations of oxidation states (Cu⁺/Cu²⁺), and its catalytic enhancements are promoted by its structural and electronic complementarity with Fe₂O₃. 

The group employed various characterization methods commonly used to prove the structure and reactivity of the catalyst. The nanoscale morphology and distribution of oxygen vacancies were observed using scanning and transmission electron microscopy (SEM, TEM), and the phase composition was determined by X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) was employed to investigate surface oxidation states, while UV-Vis spectroscopy provided insights into the optical properties and reaction pathways.