School of Energy Science & Engineering, Central South University

CO2的过度排放是 21 世纪人类面临的最大环境问题之一,严重威胁人类社会的可持续发展。在各种实现碳捕集和转化的方法中,通过电催化方法将 CO2转化为高值附加产品能有效缓解环境保护和工业生产的压力,提高碳资源的利用率,助力实现碳中和目标。 相较于在高温高压条件下实现工业尿素合成,电催化共还原 CO2与 NO-2 / NO-3生产尿素反应条件温和、能耗低、二次污染小,是一种具有工业化应用前景的 CO2利用方式。 本论文综述了 CO2与 NO-2 / NO-3电催化合成尿素的研究进展,重点从催化剂的设计合成以及 C—N 耦合机制两方面讨论了尿素在不同催化剂上的形成过程及其内在机制。 设计可以共吸附并还原 CO2 与 NO-3 / NO-2 的材料是电催化合成尿素所面临的的关键挑战。 前期研究表明引入缺陷和/ 或掺杂异质原子等方式是改善催化剂电子结构,实现 CO2 和NO-3 / NO-2 共吸附,提升尿素合成效率的有效方式。 针对尿素合成的机理,报道最多的是由∗CO 和∗NH2中间体或∗COOH 和∗NH2中间体直接偶联生成尿素;C—N 耦合过程中间产物的确定对指导催化剂的设计具有重要意义。 其中,关键 N 中间体存在形式主要有∗NH2、∗NH2OH、∗NH 和∗NO-2,关键 C 中间体主要有∗CO 和∗COOH 两种。 基于对催化剂设计合成和尿素形成机理的讨论,本论文对相关领域未来的研究重点和难点进行了进一步的总结和展望。

The excessive emission of CO2 is one of the biggest environmental issues facing the 21st cen⁃tury, which seriously threatens the sustainable development of human society. In all kinds of ways to a⁃chieve carbon capture and transformation, converting CO2 to high-value additional products based onelectrocatalytic method is an effective way to relieve the pressure of environmental protection and indus⁃trial production, improve the utilization of carbon resources, and contribute to achieving the goal of car⁃bon neutrality. Compared with industrial urea synthesis under high temperature and high pressure con⁃ditions, the electrocatalytic co-reduction of CO2 and NO2 / NO3 to urea under mild conditions with lowenergy consumption and low secondary pollution is a promising way for industrial CO2 utilization. Fromthis perspective, research progress toward electrocatalytic synthesis of urea by CO2 and NO2 / NO3 is re⁃viewed based on the urea formation process and its intrinsic mechanism on different catalysts with thedesign and synthesis of catalyst and C—N coupling mechanism being highlighted. Designing materialsthat can co-adsorb and co-reduce CO2 and NO3 / NO2 is a key challenge for the electrocatalytic synthe⁃sis of urea. Previous research shows that introducing defects and / or doping heteroatoms is an effectiveway to improve the electronic structure of the catalyst, realize the co-adsorption of CO2 and NO3, andimprove the efficiency of urea synthesis. For the mechanisms of urea synthesis, the most reported mech⁃anism is that urea is generated by direct coupling of ∗CO and ∗NH2 intermediates or ∗COOH and∗NH2 intermediates. The determination of intermediates in the C—N coupling process is important inguiding the design of catalysts. The forms of key N intermediates mainly include ∗NH2, ∗NH2OH,∗NH and ∗NO2, and the key C intermediates mainly include ∗CO and ∗COOH. Besides, the fu⁃ture research emphasis and difficulties in related fields are further summarized and proposed based onthe discussion of the catalyst design synthesis and urea formation mechanisms.

国家自然科学基金项目(22106183);湖南省自然科学基金项目(2022JJ40575);湖南省科技创新领军人才计划项目(2021RC4005)

0 引 言
1 催化剂的设计与合成
1.1 金 属
1.2 金属氧化物
1.3 单原子
1.4 其 他
2 C—N耦合机制
3 结论与展望

陈红梅, 杨泽群, 陈搏实, 等. CO2 与 NO-2 / NO-3 电催化合成尿素研究进展[J]. 能源环境保护, 2023, 37(3): 88-97.

CHEN Hongmei, YANG Zequn, CHEN Boshi, et al. Progress of urea electrocatalytic synthesis based on CO2 andnitrite/ nitrate[J]. Energy Environmental Protection, 2023, 37(3): 88-97.