School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, P. R. China.
Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang, Hunan, 414006, P. R. China.
Small. 2022 Jun;18(22):e2201391. doi: 10.1002/smll.202201391. Epub 2022 May 6.
Single-atom sites can not only act as active centers, but also serve as promising catalyst regulators and/or promoters. However, in many complex reaction systems such as electrochemical CO reduction reaction (CO RR), the introduction of single-atom regulators may inevitably induce the competitive hydrogen evolution reaction (HER) and thus reduce the selectivity. Here, the authors demonstrate that introducing HER-inert main-group metal single atoms adjacent to transition-metal single atoms can modify their electronic structure to enhance the CO RR to CO without inducing the HER side reaction. Dual-metal Cu and In single-site atoms anchored on mesoporous nitrogen-doped carbon (denoted as Cu-In-NC) are prepared by the pyrolysis of a multimetallic metal-organic framework. Cu-In-NC shows a high faradic efficiency of 96% toward CO formation at -0.7 V versus reversible hydrogen electrode, superior to that of its monometallic single-atom counterparts. Density functional theory studies reveal that the HER-inert In sites can activate the adjacent Cu sites through electronic modifications, strengthening the binding of *COOH intermediate and thus boosting the electrochemical reduction of CO to CO.
单原子位点不仅可以作为活性中心，还可以作为有前途的催化剂调节剂和/或促进剂。然而，在许多复杂的反应体系中，如电化学 CO 还原反应（CO RR），引入单原子调节剂可能不可避免地会引起竞争性的析氢反应（HER），从而降低选择性。在这里，作者证明，在过渡金属单原子附近引入对 HER 惰性的主族金属单原子可以修饰它们的电子结构，从而增强 CO RR 至 CO，而不会引发 HER 副反应。通过多金属金属有机骨架的热解制备了锚定在介孔氮掺杂碳上的双金属 Cu 和 In 单原子位点（表示为 Cu-In-NC）。Cu-In-NC 在相对于可逆氢电极的-0.7 V 下对 CO 形成表现出 96%的高法拉第效率，优于其单金属单原子对应物。密度泛函理论研究表明，对 HER 惰性的 In 位可以通过电子修饰激活相邻的 Cu 位，加强*COOH 中间体的结合，从而促进 CO 的电化学还原为 CO。
