Palladium-catalysed cross-coupling reactions, central tools in fine-chemical synthesis, predominantly employ soluble metal complexes despite recognized challenges with product purification and catalyst reusability^1,2,3. Attempts to tether these homogeneous catalysts on insoluble carriers have been thwarted by suboptimal stability, which leads to a progressively worsening performance due to metal leaching or clustering⁴. The alternative application of supported Pd nanoparticles has faced limitations because of insufficient activity under the mild conditions required to avoid thermal degradation of the substrates or products. Single-atom heterogeneous catalysts lie at the frontier^{5,6,7,8,9,10,11,12,13,14,15,16,17,18}. Here, we show that the Pd atoms anchored on exfoliated graphitic carbon nitride (Pd-ECN) capture the advantages of both worlds, as they comprise a solid catalyst that matches the high chemoselectivity and broad functional group tolerance of state-of-the-art homogeneous catalysts for Suzuki couplings, and also demonstrate a robust stability in flow. The adaptive coordination environment within the macroheterocycles of ECN facilitates each catalytic step. The findings illustrate the exciting opportunities presented by nanostructuring single atoms in solid hosts for catalytic processes that remain difficult to heterogenize.

钯催化的交叉偶联反应是精细化学合成的核心工具，主要采用可溶性金属配合物，尽管在产品纯化和催化剂可重复使用性方面存在公认的挑战^1,2,3。将这些均相催化剂束缚在不溶性载体上的尝试受到了次优稳定性的阻碍，这导致由于金属浸出或聚集⁴导致性能逐渐恶化。由于在避免基材或产品热降解所需的温和条件下活性不足，负载型 Pd 纳米颗粒的替代应用面临限制。单原子多相催化剂处于前沿^{5,6,7,8,9,10,11,12,13,14,15,16,17,18}. 在这里，我们展示了锚定在剥离的石墨氮化碳 (Pd-ECN) 上的 Pd 原子兼具了两者的优势，因为它们包含一种固体催化剂，与最先进的高化学选择性和广泛的官能团耐受性相匹配用于 Suzuki 偶合器的均相催化剂，并且还表现出强大的流动稳定性。ECN 大杂环内的适应性协调环境促进了每个催化步骤。这些发现说明了在固体主体中纳米结构单个原子用于催化过程仍然难以异质化的令人兴奋的机会。