Liu Tianyang, Wang Yu, Li Yafei
Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, P. R. China.
JACS Au. 2023 Feb 15;3(3):943-952. doi: 10.1021/jacsau.3c00026. eCollection 2023 Mar 27.
Metal-nitrogen-carbon single-atom catalysts (SACs) have exhibited substantial potential for CO electroreduction. Unfortunately, the SACs generally cannot generate chemicals other than CO, while deep reduction products are more appealing because of their higher market potential, and the origin of governing CO reduction (COR) remains elusive. Here, by using constant-potential/hybrid-solvent modeling and revisiting Cu catalysts, we show that the Langmuir-Hinshelwood mechanism is of importance for *CO hydrogenation, and the pristine SACs lack another site to place *H, thus preventing their COR. Then, we propose a regulation strategy to enable COR on the SACs: (I) the metal site has a moderate CO adsorption affinity; (II) the graphene skeleton is doped by a heteroatom to allow *H formation; and (III) the distance between the heteroatom and the metal atom is appropriate to facilitate *H migration. We discover a P-doped Fe-N-C SAC with promising COR reactivity and further extend this model to other SACs. This work provides mechanistic insight into the limiting factors of COR and highlights the rational design of the local structures of active centers in electrocatalysis.
金属-氮-碳单原子催化剂（SACs）在CO电还原方面展现出了巨大潜力。不幸的是，SACs通常只能生成CO，而无法生成其他化学品，然而深度还原产物因其更高的市场潜力而更具吸引力，并且控制CO还原（COR）的根源仍然难以捉摸。在此，通过使用恒电位/混合溶剂模型并重新审视Cu催化剂，我们表明朗缪尔-欣谢尔伍德机制对CO加氢很重要，并且原始的SACs缺乏放置H的另一个位点，从而阻碍了它们的COR。然后，我们提出了一种在SACs上实现COR的调控策略：（I）金属位点具有适度的CO吸附亲和力；（II）石墨烯骨架由杂原子掺杂以允许H形成；（III）杂原子与金属原子之间的距离合适以促进H迁移。我们发现了一种具有良好COR反应活性的P掺杂Fe-N-C SAC，并将该模型进一步扩展到其他SACs。这项工作为COR的限制因素提供了机理见解，并突出了电催化中活性中心局部结构的合理设计。
