Li Panpan, Li Ran, Liu Yuanting, Xie Minghao, Jin Zhaoyu, Yu Guihua
College of Materials Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
Materials Science and Engineering Program and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
J Am Chem Soc. 2023 Mar 22;145(11):6471-6479. doi: 10.1021/jacs.3c00334. Epub 2023 Mar 10.
Electroreduction of nitrate to ammonia offers a promising pathway for nutrient recycling and recovery from wastewater with energy and environmental sustainability. There have been considerable efforts on the regulation of reaction pathways to facilitate nitrate-to-ammonia conversion over the competing hydrogen evolution reaction but only with limited success. Here, we report a Cu single-atom gel (Cu SAG) electrocatalyst that produces NH from both nitrate and nitrite under neutral conditions. Given the unique mechanism of NO activation on Cu SAGs with spatial confinement and strengthened kinetics, a pulse electrolysis strategy is presented to cascade the accumulation and conversion of NO intermediates during NO reduction with the prohibited competition from the hydrogen evolution reaction, thus substantially enhancing the Faradaic efficiency and the yield rate for ammonia production compared with constant potential electrolysis. This work underlines the cooperative approach of the pulse electrolysis and SAGs with three-dimensional (3D) framework structures for highly efficient nitrate-to-ammonia conversion enabled by tandem catalysis of unfavorable intermediates.
将硝酸盐电还原为氨为从废水中进行营养物质回收和再利用提供了一条充满前景的途径，具有能源和环境可持续性。人们在调节反应途径以促进硝酸盐向氨的转化、同时抑制竞争性析氢反应方面付出了巨大努力，但成效有限。在此，我们报道了一种铜单原子凝胶（Cu SAG）电催化剂，它能在中性条件下将硝酸盐和亚硝酸盐转化为氨。鉴于在具有空间限制和强化动力学的Cu SAG上NO活化的独特机制，我们提出了一种脉冲电解策略，以在NO还原过程中使NO中间体的积累和转化串联进行，同时避免析氢反应的竞争，从而与恒电位电解相比，大幅提高了法拉第效率和氨的产率。这项工作强调了脉冲电解和具有三维（3D）框架结构的SAG的协同方法，通过对不利中间体的串联催化实现高效的硝酸盐向氨的转化。
