| Dec 23, 2025 |
Scientists develop metal-organic framework composites that convert nitrogen to ammonia using renewable electricity, offering a cleaner fertilizer alternative.
(Nanowerk News) For more than a century, the world has relied on the Haber-Bosch process to convert atmospheric nitrogen into ammonia, the key ingredient in synthetic fertilizers. This industrial workhorse feeds billions of people, but it comes at a steep environmental cost: the process demands extreme temperatures and pressures, burns through fossil fuels, and pumps substantial amounts of carbon dioxide into the atmosphere.
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Meanwhile, nitrate contamination from fertilizer runoff and industrial waste has become a growing threat to water supplies worldwide. And as researchers explore ammonia’s potential as a carbon-free way to store and transport hydrogen energy, demand for cleaner nitrogen chemistry keeps climbing.
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The problem? Current electrochemical systems that could harness renewable electricity to do this work suffer from sluggish reactions, poor electrical conductivity, and unwanted side reactions that produce hydrogen instead of ammonia. These challenges have pushed scientists to dig deeper into a promising class of hybrid materials called metal-organic framework nanoparticle (MOF-NP) composites.
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Now, an international research team from Sungkyunkwan University, Yangzhou University, Tsinghua University, and partner institutions has published a comprehensive analysis of how these engineered materials can transform nitrogen electrochemistry. Their study, released in the journal eScience (“Rational design of metal–organic framework-nanoparticle composite electrocatalysts for sustainable nitrogen electrochemistry”), reveals how combining porous metal-organic frameworks with tiny metal nanoparticles creates catalysts that outperform existing technologies across multiple nitrogen reactions.
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Building Better Catalysts
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The researchers identified three main strategies scientists use to build these hybrid materials: growing metal-organic frameworks around existing nanoparticles, loading nanoparticles into pre-made frameworks, or creating both components simultaneously in a single reaction. Each approach gives chemists different levels of control over how electrons flow through the material, how gases access the active sites, and how the metal and framework components interact.
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These design choices matter because pristine metal-organic frameworks, while excellent at capturing and organizing molecules, struggle with electrical conductivity and lack enough reactive sites to drive chemical transformations efficiently.
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Making Ammonia From Air
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For nitrogen reduction, the process of converting atmospheric nitrogen gas into ammonia, the team found that embedding nanoparticles of gold, palladium-copper alloys, ruthenium, or molybdenum disulfide within framework structures dramatically improves performance. These embedded particles help nitrogen molecules stick to the catalyst surface, stabilize the fragile intermediate compounds that form during the reaction, and block the competing hydrogen evolution reaction that wastes energy.
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Specific examples from the research include gold-copper particles housed in ZIF-8 frameworks, palladium-copper catalysts wrapped in moisture-repelling coatings, and single ruthenium atoms dispersed throughout UiO-66 structures. All deliver high ammonia yields with improved efficiency at converting electrical energy into chemical bonds.
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Cleaning Up Contaminated Water
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The composites also excel at nitrate reduction, which transforms harmful nitrate pollutants into valuable ammonia. Systems like palladium nanodots on zirconium-based frameworks, copper particles within copper-organic structures, and mixed copper-zinc materials achieve exceptional selectivity and conversion rates. Their porous architectures stabilize key reaction intermediates and speed up the transfer of electrons and protons needed to complete the transformation.
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Powering the Ammonia Economy
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For ammonia oxidation, the reverse reaction needed to release energy from ammonia fuel, the researchers highlighted platinum-iridium-zinc nanoparticles supported on carbon frameworks derived from cerium oxide and ZIF-8. These catalysts lower the energy barrier for breaking nitrogen-hydrogen bonds and outperform conventional platinum-based materials.
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Engineering at the Atomic Level
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Across all three reaction types, the study demonstrates that fine-tuning works. Introducing defects into the framework structure, adjusting how metals bond to organic linkers, trapping nanoparticles in specific locations, and modifying electronic properties all significantly boost activity, selectivity, and durability.
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The authors argue that MOF-NP composites represent a powerful platform for reshaping how humanity manages nitrogen using renewable electricity. They emphasize that the partnership between porous framework networks and highly reactive nanoparticles allows precise control over how molecules stick to surfaces, how intermediates remain stable, and how charge moves through the system. These capabilities, they note, prove essential for making ammonia efficiently, cleaning nitrate-contaminated water at scale, and building high-performance catalysts for ammonia-based energy systems.
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The researchers also point to the importance of advanced characterization techniques that can watch these reactions unfold in real time, computer modeling that predicts how new materials will behave, and artificial intelligence tools that can accelerate the discovery of even better catalysts.
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A Sustainable Future for Nitrogen
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The practical implications extend across environmental and industrial sectors. Converting nitrogen to ammonia under normal conditions using renewable power could dramatically reduce dependence on the carbon-intensive Haber-Bosch process, opening the door to distributed, clean fertilizer production. Efficient nitrate-to-ammonia conversion offers a two-for-one benefit: cleaning polluted water while recovering a valuable chemical. And improved ammonia oxidation catalysts support the emerging vision of ammonia as a carbon-neutral fuel, enabling safe energy storage and conversion without greenhouse gas emissions.
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With continued progress in manufacturing these materials at scale and fine-tuning the interfaces between their components, MOF-NP composites may become foundational technologies for sustainable nitrogen management in the decades ahead.
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