Magnetic Field During Catalyst Synthesis Triples Ammonia Yield
Berlin, June 2, 2026 – A groundbreaking study by a team from Helmholtz-Zentrum Berlin (HZB) and the University of Cologne has revealed a novel method to significantly enhance ammonia production. By applying an external magnetic field during the synthesis of CoFe₂O₄ electrocatalysts, researchers have achieved a threefold increase in ammonia yield during electrocatalytic conversion. This innovative approach, detailed in the journal ‘Advanced Functional Materials’, offers a scalable strategy for developing next-generation electrocatalysts crucial for efficient and sustainable chemical production.
The well-known Haber-Bosch process, currently responsible for ammonia synthesis, consumes 1 to 2 percent of the world’s energy and contributes almost 1 percent to annual greenhouse gas emissions. The new method focuses on the electrochemical conversion of nitrate into ammonia, addressing the issue of nitrate accumulation in intensive agriculture, which is particularly harmful to waterways. However, this process requires suitable catalysts to prevent the formation of hydrogen and nitrogen-containing by-products. Spinel transition metal oxides, especially thin films of CoFe₂O₄, have shown particular promise in this area.
Enhanced Efficiency Through Magnetic Field Control
Dr. Marcel Risch from HZB and Professor Dr. Sanjay Mathur from the University of Cologne led the study that demonstrated the immense potential of an external magnetic field applied during catalyst synthesis. “By applying a magnetic field during chemical vapor deposition, we aimed to tailor the surface states and cation distribution in CoFe₂O₄ thin films to create more efficient surface-engineered electrocatalysts,” stated Professor Mathur, who oversaw the material synthesis.
The results confirmed their hypothesis: CoFe₂O₄ layers produced under a 1 Tesla (1 T) magnetic field exhibited the best performance, yielding three times more ammonia compared to those produced without a magnetic field. This highlights the effectiveness of magnetic-field-controlled surface engineering. Furthermore, when comparing the CoFe₂O₄-1T catalyst with pure iron oxide Fe₃O₄-1T, also synthesized under a 1 Tesla magnetic field, the ammonia yield was a remarkable 22 times higher, underscoring the critical role of cobalt in nitrate reduction.
Cobalt’s Decisive Role and Scalability for Practical Applications
Supplementary Density Functional Theory (DFT) calculations corroborate that cobalt effectively suppresses the competing hydrogen evolution reaction while simultaneously promoting nitrate conversion. “The applied magnetic field stabilizes the catalytically active Co²⁺ ions at octahedral sites, which evidently lowers the kinetic barriers for nitrate reduction,” explained Dr. Risch.
This study demonstrates that a magnetic field, alongside temperature and pressure, serves as an effective parameter for controlling cation distribution, magnetic domain structures, and surface states at the atomic level during the growth of thin-film catalysts. Crucially, even though the magnetic field is only applied during thin-film growth, the improvements in efficiency are sustained during field-free electrochemical operation. “This makes our approach particularly promising for practical applications, since no external magnetic field is required during electrolysis,” Dr. Risch emphasized.
Surface Roughness and Future Research
Scanning electron microscope images revealed that the surfaces of the CoFe₂O₄ thin films became systematically rougher, and thus larger, with stronger magnetic fields during synthesis. “We hope that these results will stimulate broader exploration of magnetic-field-assisted strategies for tailoring electrocatalysts,” Professor Mathur concluded. This research paves the way for more sustainable and efficient chemical production processes, especially in the context of ammonia synthesis and the broader hydrogen economy.
Publication: Advanced Functional Materials (2026): Magnetic-Field Control of Surface States in CoFe₂O₄ Thin Films for Nitrate Electroreduction to Ammonia
DOI: 10.1002/adfm.76213
Source: HZB press release, 1 June 2026
