Despite dominating industrial processes, heterogeneous catalysts remain challenging to characterize and control. This is largely attributable to the diversity of potentially active sites at the catalyst-reactant interface and the complex behaviour that can arise from interactions between active sites. Surface-supported, single-site molecular catalysts aim to bring together benefits of both heterogeneous and homogeneous catalysts, offering easy separability while exploiting molecular design of reactivity, though the presence of a surface is likely to influence reaction mechanisms. Here, we use metal-organic coordination to build reactive Fe-terpyridine sites on the Ag(111) surface and study their activity towards CO and C₂H₄ gaseous reactants using low-temperature ultrahigh-vacuum scanning tunnelling microscopy, scanning tunnelling spectroscopy, and atomic force microscopy supported by density-functional theory models. Using a site-by-site approach at low temperature to visualize the reaction pathway, we find that reactants bond to the Fe-tpy active sites via surface-bound intermediates, and investigate the role of the substrate in understanding and designing single-site catalysts on metallic supports.

尽管在工业过程中占主导地位，但多相催化剂的表征和控制仍然具有挑战性。这主要归因于催化剂-反应物界面潜在活性位点的多样性以及活性位点之间相互作用可能产生的复杂行为。表面负载的单中心分子催化剂旨在结合多相和均相催化剂的优点，提供易于分离性，同时利用反应性的分子设计，尽管表面的存在可能会影响反应机制。在这里，我们使用金属有机配位在 Ag(111) 表面构建反应性 Fe-三联吡啶位点，并研究它们对 CO 和 C ₂ H _4的活性使用低温超高真空扫描隧道显微镜、扫描隧道光谱和密度泛函理论模型支持的原子力显微镜分析气态反应物。在低温下使用逐点方法可视化反应途径，我们发现反应物通过表面结合的中间体与 Fe-tpy 活性位点结合，并研究底物在理解和设计单点催化剂中的作用在金属支架上。