华东理工大学杨雪晶团队报道了镍催化尿素电解中过氧化氮的破译与抑制。相关研究成果发表在2021年9月23日出版的《德国应用化学》。

尿素电解是一种很有前景的同时制氢和氮减排技术，进而向水能转化的技术。

其可持续性目前建立在无害N₂产品的基础上；然而，在此，研究人员发现普遍使用的镍基催化剂通常会将尿素过度氧化成具有约80%法拉第效率的NO^2-产物，对环境造成潜在的二次危害。还检测到微量过量氧化的NO^3-和N₂O。通过¹⁵N同位素和尿素类似物，研究人员得出了一个氮反应网络，包括通过OH辅助C-N裂解的NO₂生成途径和分子内和分子间耦合的两条N₂生成途径。

密度泛函理论（DFT）计算证实C-N劈裂在能量上更有利。受该机制的启发，开发了聚苯胺涂层策略，以局部富集尿素，使氮气产量增加2倍。

该发现为水能系统中氮的命运提供了补充性的见解。

附：英文原文

Title: Deciphering and Suppressing the Over-oxidized Nitrogen in Nickel-catalyzed Urea Electrolysis

Author: Jianan Li, Jili Li, Tao Liu, Lin Chen, Yefei Li, Hualin Wang, Xiurong Chen, Ming Gong, Zhi-Pan Liu, Xuejing Yang

Issue&Volume: 2021-09-23

Abstract: Urea electrolysis is a prospective technology for simultaneous H2  production and nitrogen abatement toward water-energy nexus. Its sustainability is currently founded on the innocuous N2  products; however, herein, we discovered the prevalent nickel-based catalysts could generally over-oxidize urea into NO2-  products with ~80% Faradaic efficiencies, posing potential secondary hazard to the environment. Trace amounts of over-oxidized NO3-  and N2O were also detected. By  15N isotopes and urea analogues, we derived a nitrogen fate network, involving a NO2-  formation pathway  via  OH--assisted C-N cleavage and two N2  formation pathways of intra- and inter-molecular coupling. Density functional theory (DFT) calculation confirmed that C-N cleavage is energetically more favorable. Inspired by the mechanism, a polyaniline coating strategy was developed to locally enrich urea for encouraging N2  production by 2-folds. These findings provide complementary insights into the nitrogen fate in water-energy nexus systems.

DOI: 10.1002/anie.202107886

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202107886