Single-atom catalysts (SACs) often exhibit superior activity and selectivity in heterogeneous catalysis because of their maximized atom utilization and unique coordination environments. However, most reported studies about SACs in heterogeneous catalysis focus on model reactions with simple molecules. In addition, many reported single atoms are confined in microporous structures, hindering the mass transfer of molecules with large sizes, thus limiting their practical applications in industry. In this study, we report a molten salt-assisted method to synthesize metal single atoms anchored on a hierarchical porous nitrogen-doped carbon support (denoted as M₁/h-NC, M includes Co, Fe, Ni, Mn, and Cu). Taking Co₁/h-NC as an example, compared to the control sample which has Co single atoms being encapsulated in a microporous N-doped carbon support (denoted as Co₁/m-NC), Co₁/h-NC exhibits significantly higher catalytic activity in the selective hydrogenation of large-sized pharmaceutical molecules, such as nimodipine (calcium channel blocker) and 2-(3′,4′-methylenedioxyphenylethyl)quinoline (antispasmodic natural alkaloid intermediate). The superior catalytic performance of Co₁/h-NC is directly ascribed to the integration of the advantages of single-atom active sites and hierarchical mesoporous structure, which is beneficial for the mass transfer of molecules with large sizes and enables nearly all the Co single atoms to be accessible for catalytic reactions.

中文翻译：

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将金属单原子整合到多孔氮掺杂碳上，以实现制药业中大分子的高效加氢

单原子催化剂（SAC）在多相催化中通常表现出优异的活性和选择性，这是因为它们具有最大的原子利用率和独特的配位环境。然而，关于非均相催化中SAC的大多数报道研究都集中在与简单分子的模型反应上。另外，许多报道的单原子被限制在微孔结构中，阻碍了大尺寸分子的传质，从而限制了它们在工业中的实际应用。在这项研究中，我们报告了一种熔融盐辅助方法，用于合成锚固在分层的多孔氮掺杂碳载体（表示为M ₁ / h-NC，M包括Co，Fe，Ni，Mn和Cu）上的金属单原子。以Co ₁/ h-NC作为示例，与将Co单原子封装在微孔N掺杂碳载体（表示为Co ₁ / m-NC）中的对照样品相比，Co ₁ / h-NC表现出明显更高的催化活性在大型药物分子（例如尼莫地平（钙通道阻滞剂）和2-（3'，4'-亚甲基二氧苯基乙基）喹啉（解痉型天然生物碱中间体））的选择性加氢中的作用。Co ₁ / h-NC的优异催化性能直接归因于单原子活性位点和分层介孔结构的优势的整合，这有利于大分子分子的传质并使几乎所有Co单原子可用于催化反应。