A research team led by professor Yousung Jung from the Department of Chemical and Biological Engineering at Seoul National University College of Engineering has developed a new catalyst design principle that suppresses the hydrogen evolution reaction, which interferes with ammonia production, while maintaining the nitrogen reduction reaction that produces ammonia.
Ammonia can store large amounts of hydrogen and remains in a liquid state at room temperature, making it easy to transport. For this reason, it has gained attention as a next-generation eco-friendly energy carrier capable of delivering energy generated from renewable sources such as wind and solar power. However, the conventional ammonia synthesis method (the Haber–Bosch process) requires high temperatures and pressures, as well as high energy consumption and carbon emissions.
As an alternative, the electrochemical nitrogen reduction reaction (NRR)—which produces ammonia using only water, nitrogen and electricity—has attracted attention. However, a major limitation has been that hydrogen is produced preferentially over ammonia, significantly lowering production efficiency.
The research team proposed a new catalyst design principle that selectively suppresses hydrogen evolution by controlling the structure of molecules participating in the reaction. This study is expected to overcome efficiency limitations in eco-friendly ammonia production and provide a foundation for the stable supply of carbon-free ammonia-based hydrogen energy to households and industrial sites.
Shifting focus to the reaction environment
The study is published in the Journal of the American Chemical Society. Unlike conventional approaches, the research team focused on a new strategy of designing the reaction environment itself.
Previous studies primarily attempted to suppress hydrogen evolution by controlling protons, such as by adjusting the acidity of the electrolyte. However, because protons are also required for ammonia synthesis, reducing their availability suppresses both hydrogen evolution and nitrogen reduction simultaneously.
To overcome this limitation, the team proposed a new approach that selectively blocks only the hydrogen evolution reaction while preserving nitrogen reduction activity. The idea was inspired by nature: Proteins often act as catalysts and selectively react only with substrates that fit their shapes. The researchers applied this principle to electrochemical reactions.
The team successfully increased the energy barrier of the Volmer reaction, the first step in hydrogen evolution, by controlling the steric structure of proton donors.
Steric hindrance slows hydrogen formation
The key lies in the geometric positioning of reactants. Similar to how incorrectly placed blocks in a game of Tetris hinder progress, increased steric hindrance makes it difficult for protons to approach the electrode surface, significantly slowing the hydrogen evolution reaction.
In contrast, the nitrogen reduction reaction is minimally affected because protons interact with nitrogen molecules that protrude outward from the catalyst surface rather than the electrode surface itself. In other words, by selectively blocking access to the electrode surface through steric hindrance, the researchers were able to suppress hydrogen evolution while maintaining nitrogen reduction.
In addition, microkinetic modeling confirmed that greater steric hindrance allows high Faradaic efficiency to be maintained over a wide voltage range.
From lab efficiency to broader use
This study is significant because it proposes a design principle capable of increasing the Faradaic efficiency of electrochemical nitrogen reduction from around 70% to nearly 100%. The findings are expected to enable localized production of eco-friendly ammonia near renewable energy sources, eliminating the need for large-scale chemical plants and contributing to the realization of a clean hydrogen economy.
The approach is also expected to be widely applicable to other electrochemical catalytic systems, such as carbon dioxide reduction, where controlling competing reactions is critical.
Jung's team plans to expand this concept to other electrochemical reactions and accelerate commercialization by identifying highly active catalyst materials that can incorporate this design principle, ultimately developing catalytic systems with both high selectivity and high activity.
Jung said, "This study is significant in that it proposes a precise interfacial design strategy capable of selectively suppressing only competing reactions in electrochemical nitrogen reduction, where technical limitations have long been evident. It will serve as a foundational technology not only for eco-friendly ammonia production but also for improving the efficiency of a wide range of interfacial electrochemical reactions."
Publication details
Dongmin Park et al, Steric Hindrance of Proton Donors Modulates Heterogeneous Electrochemical Nitrogen Reduction Reaction Selectivity in Nonaqueous Electrolytes, Journal of the American Chemical Society (2026). DOI: 10.1021/jacs.6c07080
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Citation: New catalyst design selectively suppresses competing hydrogen reaction in ammonia synthesis (2026, August 4) retrieved 5 August 2026 from https://phys.org/news/2026-08-catalyst-suppresses-hydrogen-reaction-ammonia.html
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