Ammonia (NH 3 ) is a critical chemical widely used in fertilizers, chemical synthesis, and energy applications. Its industrial production predominantly relies on the Haber-Bosch process, which operates under high temperature and pressure and is associated with considerable energy consumption and CO 2 emissions. Developing sustainable and efficient alternatives for ammonia synthesis is therefore of significant interest.
Electrocatalytic nitrogen reduction reactions (NRR) have been investigated as greener routes to NH 3 , but their efficiency is limited by the strong N≡N bond and sluggish multi-electron kinetics. In comparison, the electrocatalytic nitric oxide reduction reaction (NORR) has emerged as a promising alternative. NO, a major pollutant from industrial emissions, can be directly converted to NH 3 under milder conditions, providing simultaneous environmental remediation and chemical synthesis.
However, NORR faces challenges, including competitive hydrogen evolution reaction (HER), low NO solubility in aqueous electrolytes, and limited interfacial mass transport, which collectively reduce reaction efficiency and selectivity. Addressing these limitations requires catalysts capable of enhancing NO adsorption, accelerating diffusion, and maintaining high activity.
To overcome these challenges, Prof. Lina Li and her team at Jilin University introduced porous aromatic frameworks (PAFs) into the NORR system. Using tetraphenylporphyrin (TPP) as the building block, they constructed a PAF-TPP material via a Scholl reaction and subsequently incorporated Co 2+ ions to generate well-defined Co-N 4 active sites, forming the PAF-TPP-Co catalyst. The material combines a high-surface-area porous structure with atomically dispersed Co active centers, creating a synergistic “adsorption–transport–catalysis” environment.
The PAF network enriches NO molecules at the catalyst interface and facilitates rapid diffusion, while Co-N₄ sites selectively activate NO for multi-electron conversion to NH₃, suppressing competing HER. At -0.6 V vs. RHE, PAF-TPP-Co achieves an ammonia production rate of 914.2 μg·h -1 ·mg cat -1 with a Faradaic efficiency of 71.3%. In situ infrared spectroscopy, Raman spectroscopy, and density functional theory (DFT) calculations confirm that the synergistic structure optimizes adsorption energetics, lowers reaction barriers, and accelerates kinetics.
“This study demonstrates how porous aromatic frameworks can be integrated with active site engineering to achieve highly efficient NO-to-ammonia conversion,” said Prof. Lina Li. “By combining NO enrichment, rapid mass transport, and catalytic activation within a single architecture, our approach provides a new strategy for designing high-performance NORR catalysts and valorizing industrial NO emissions.”
The work opens a new avenue for applying porous frameworks in electrocatalysis, showing that coupling structural porosity with single-atom active sites can significantly enhance interfacial utilization and reaction efficiency. These findings provide a practical route toward sustainable ammonia synthesis while addressing environmental pollution from NO-containing exhaust gases.
Other contributors include Xinxin Yuan, Yuyue Peng, Lei Zhang, Hongliang Lei and Zhiyi Li from the School of Jilin University.
This work was supported by the National Key R&D Program (grant number 2023YFC2811200). We acknowledge all the experimental staff in the Department of Materials Science and Engineering at Jilin University.
DOI Link:
https://doi.org/10.26599/NR.2026.94908876
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Nano Research
Enhancing NO reduction to ammonia via Porous Aromatic Frameworks: Co-Modified PAF-TPP for efficient mass transfer and electrocatalytic performance
26-May-2026