Selective Electrocatalytic Nitrate Reduction to Ammonia Enabled by a [8+2]-Connected Three-Dimensional Metal–Bipyridine Covalent Organic Framework

Q: What type of study is this?

This is a In Vitro Study study.

Tsukasa Irie; Ayumu Kondo; Kai Sun; Kohki Sasaki; Mika Nozaki; Kotaro Sato; Tokuhisa Kawawaki; Yu Zhao; Saikat Das; Yuichi Negishi

doi:10.26434/chemrxiv-2025-50r8z

August 11, 2025

Selective Electrocatalytic Nitrate Reduction to Ammonia Enabled by a [8+2]-Connected Three-Dimensional Metal–Bipyridine Covalent Organic Framework

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Key Points

TU-82-Fe achieved an exceptional faradaic efficiency of 88.1% in nitrate reduction to ammonia, significantly outperforming its copper counterpart.
The framework structure allows for precise metalation, enhancing catalytic performance and stability in nitrate reduction reactions.
Density functional theory calculations indicate that TU-82-Fe has a lower energy barrier of 0.354 eV for key reaction steps, supporting its superior efficiency.
This study introduces a pioneering approach to explore three-dimensional covalent organic frameworks in electrocatalytic applications.],
simple_explanation':'Covalent organic frameworks can help reduce nitrate pollution by turning it into ammonia. One new framework, TU-82, works even better than previous ones, turning 88% of nitrate into ammonia. This method is important because it could help manage nitrates in a cleaner way for our environment. The study shows that using 3D structures opens new avenues for smarter and more effective catalysts. 🧪' } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } } },

Implication

This research demonstrates improved ammonia yields from nitrate reduction using a three-dimensional covalent organic framework, suggesting new pathways for sustainable nitrate management.

Abstract

While covalent organic frameworks (COFs) have emerged as promising electrocatalysts, all reported COF-based systems for electrocatalytic nitrate reduction to ammonia (NO3RR) have been limited to two-dimensional architectures, leaving the potential of three-dimensional (3D) frameworks untapped. Herein, we present TU-82, the first 3D COF applied to NO3RR, featuring an intricate [8+2]-connected bcu topology derived from the reticulation of an octatopic D2h-symmetric tetragonal prism node and a C2-symmetric bipyridyl linker. TU-82 exhibits high crystallinity, permanent porosity, and robust structural integrity, enabling precise postsynthetic metalation at bipyridyl coordination sites to yield catalytically active TU-82-Fe and TU-82-Cu frameworks. TU-82-Fe delivers exceptional NO3RR performance, achieving a high faradaic efficiency (FE) of 88.1% (at −0.6 V(RHE)), significantly outperforming TU-82-Cu (62.8% FE), along with a high ammonia yield rate of 2.87 mg h−1 cm−2 (at −0.8 V(RHE)). A turnover frequency of up to 7.2 h−1 and excellent operational stability further underscore its catalytic potential. Density functional theory calculations revealed that TU-82-Fe’s superior performance arises from its lower energy barrier (0.354 eV) for the rate-determining step (NO*→NHO*) along the NHO-mediated reaction pathway. This work pioneers a structural blueprint for deploying 3D COFs in electrocatalysis, fostering deeper insights into framework-controlled reactivity and offering new routes to sustainable nitrate management.

Discussion

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Cite This Study

Irie et al. (2025) studied this question.

synapsesocial.com/papers/68a36f900a429f797333288b https://doi.org/10.26434/chemrxiv-2025-50r8z

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Selective Electrocatalytic Nitrate Reduction to Ammonia Enabled by a [8+2]-Connected Three-Dimensional Metal–Bipyridine Covalent Organic Framework

Key Points

Implication

Abstract

Discussion

Cite This Study

Selective Electrocatalytic Nitrate Reduction to Ammonia Enabled by a [8+2]-Connected Three-Dimensional Metal–Bipyridine Covalent Organic Framework

Key Points

Implication

Abstract

Discussion

Cite This Study

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