Department of Chemistry and the Waterloo Institute for Nanotechnology, University of Waterloo, Ontario, N2L 3G1, Canada.
Angew Chem Int Ed Engl. 2022 Sep 26;61(39):e202209839. doi: 10.1002/anie.202209839. Epub 2022 Aug 23.
The electrochemical urea oxidation reaction (UOR) to N represents an efficient route to simultaneous nitrogen removal from N-enriched waste and production of renewable fuels at the cathode. However, the overoxidation of urea to NO usually dominates over its oxidation to N at Ni(OH) -based anodes. Furthermore, detailed reaction mechanisms of UOR remain unclear, hindering the rational catalyst design. We found that UOR to NO on Ni(OH) is accompanied by the formation of near stoichiometric amount of cyanate (NCO ), which enabled the elucidation of UOR mechanisms. Based on our experimental and computational findings, we show that the formation of NO and N follows two distinct vacancy-dependent pathways. We also demonstrate that the reaction selectivity can be steered towards N formation by altering the composition of the catalyst, e.g., doping the catalyst with copper (Ni Cu (OH) ) increases the faradaic efficiency of N from 30 % to 55 %.
电化学尿素氧化反应（UOR）将 N 转化为 N，代表了一种从富氮废水中同时去除氮并在阴极生产可再生燃料的有效途径。然而，在基于 Ni(OH)的阳极上，尿素的过度氧化通常会超过其对 N 的氧化。此外，UOR 的详细反应机制仍不清楚，这阻碍了对催化剂的合理设计。我们发现，Ni(OH)上的 UOR 伴随着近乎化学计量的氰酸盐（NCO ）的形成，这使得 UOR 机制得以阐明。基于我们的实验和计算结果，我们表明 NO 和 N 的形成遵循两种不同的、依赖空位的途径。我们还证明，通过改变催化剂的组成（例如，用铜掺杂催化剂（NiCu(OH)）），可以将反应选择性朝着 N 的形成方向引导，从而将 N 的法拉第效率从 30%提高到 55%。
