Electrocatalytic urea production from nitrate (NO3−) and carbon dioxide (CO2) provides a promising alternative to the traditional energy-intensive industrial process. However, promoting electrocatalytic carbon–nitrogen coupling and suppressing side reactions remains challenging. Here we report an efficient urea synthesis via electrochemical coupling of NO3− and CO2 using entangled iron porphyrins in three-dimensional covalent organic frameworks. The porous iron catalyst concentrates and cooperatively activates reactants, achieving a high Faradaic efficiency of 90.0%, a nitrogen selectivity of 92.4% and nearly 100% carbon selectivity. The catalyst achieves a urea yield rate of <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="44160_2025_742_Article_IEq1.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="133" /> </InlineMediaObject> <EquationSource Format="TEX">$135.6\,{\mathrm{mmol}}\,{\mathrm{g}}_{\mathrm{cat}}^{-1}\,{\mathrm{h}}^{-1}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>135.6</mn> <mspace width="0.25em" /> <mi mathvariant="normal">mmol</mi> <mspace width="0.25em" /> <msubsup> <mrow> <mi mathvariant="normal">g</mi> </mrow> <mrow> <mi mathvariant="normal">cat</mi> </mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msubsup> <mspace width="0.25em" /> <msup> <mrow> <mi mathvariant="normal">h</mi> </mrow> <mrow> <mo>−</mo> <mn>1</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation>, while maintaining activity for >100 h. Experiments and theoretical calculations suggest the plentiful Fe–N4 sites within porphyrins efficiently facilitate the conversions of CO2 to CO and NO3− to NH2, and the spatial localization of twin iron sites overcomes the unordered transfer of intermediates, enabling vectored carbon–nitrogen coupling.

Selective electrocatalytic synthesis of urea using entangled iron porphyrins in covalent organic frameworks

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发表日期：

2025年2月21日

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Chengtao Gong,
Yongwu Peng,
Mengqiu Xu,
Xiaofei Wei,
Guan Sheng,
Jialiang Liu,
Xiaowei Wu,
Xing Han,
Fangna Dai,
Jinqiao Dong,
Zhijie Chen,
Yihan Zhu,
Wei Ye,
Yong Cui

摘要

Electrocatalytic urea production from nitrate (NO₃⁻) and carbon dioxide (CO₂) provides a promising alternative to the traditional energy-intensive industrial process. However, promoting electrocatalytic carbon–nitrogen coupling and suppressing side reactions remains challenging. Here we report an efficient urea synthesis via electrochemical coupling of NO₃⁻ and CO₂ using entangled iron porphyrins in three-dimensional covalent organic frameworks. The porous iron catalyst concentrates and cooperatively activates reactants, achieving a high Faradaic efficiency of 90.0%, a nitrogen selectivity of 92.4% and nearly 100% carbon selectivity. The catalyst achieves a urea yield rate of $135.6\,{\mathrm{mmol}}\,{\mathrm{g}}_{\mathrm{cat}}^{-1}\,{\mathrm{h}}^{-1}$ $135.6 mmol g_{cat}^{- 1} h^{- 1}$ , while maintaining activity for >100 h. Experiments and theoretical calculations suggest the plentiful Fe–N₄ sites within porphyrins efficiently facilitate the conversions of CO₂ to *CO and NO₃⁻ to *NH₂, and the spatial localization of twin iron sites overcomes the unordered transfer of intermediates, enabling vectored carbon–nitrogen coupling.