2026: Spike-Embedded Nanocatalysts via Metal-Directed Carbonization for Highly Efficient and Robust Semi-Hydrogenation
Achieving high catalytic efficiency while maintaining robust structural stability is a persistent dilemma in the design of carbon-supported nanocatalysts. Herein, we report a metal-directed carbonization strategy to resolve this trade-off by utilizing hierarchical organic microspheres as precursors. The pivotal role of metal ions (e.g., Pd2+) extends beyond serving as precursors for metallic active sites, as they also facilitate carbonization at reduced temperatures and help preserve the precursor morphology during calcination. This metal-assisted aromatic coupling process reduces carbonization temperature by 130°C and drives the migration of metal nanoparticles to the tips of the carbon spikes, where they become embedded within the carbon matrix and partially exposed. Consequently, the afforded catalyst is 84 times more active than Pd/C and 14 times more active than Pd/Al2O3 for semi-hydrogenation of nitrobenzene to azoxybenzene, and maintains high activity and selectivity even in the presence of ethylenediamine and thiourea. The catalyst also displays applicability in the semi-hydrogenation of alkynes to alkenes with excellent chemoselectivity. Overall, the templated strategy is general, extends to multiple metals and microsphere morphologies, and provides a scalable route to carbon-supported catalysts that combine site accessibility with nanoparticle stabilization for challenging, poison-prone reactions.
在设计碳载纳米催化剂时，如何在实现高催化效率的同时保持稳健的结构稳定性，一直是一个难以解决的两难问题。在此，我们报道了一种“金属导向碳化”策略，通过利用分级有机微球作为前体，成功化解了这一矛盾。金属离子（例如 Pd²⁺）在此过程中发挥着关键作用，其功能远不止作为金属活性位点的前体；它们还能促进低温下的碳化过程，并有助于在煅烧过程中保持前体原有的形貌。这种金属辅助的芳香偶联过程将碳化温度降低了 130°C，并驱动金属纳米颗粒迁移至碳刺结构的尖端，使其嵌入碳基体内部并保持部分暴露状态。因此，所制备的催化剂在硝基苯半加氢制偶氮氧苯的反应中，其活性是传统 Pd/C 催化剂的 84 倍，是 Pd/Al₂O₃ 催化剂的 14 倍；即使在乙二胺和硫脲共存的条件下，该催化剂依然能保持极高的活性和选择性。此外，该催化剂在炔烃半加氢制烯烃的反应中也展现出良好的应用潜力，并表现出优异的化学选择性。综上所述，这种模板化策略具有普适性，可适用于多种金属元素及不同形貌的微球前体；它为制备碳载催化剂提供了一条可规模化的合成途径，能够巧妙地将活性位点的可及性与纳米颗粒的稳定性相结合，从而为那些极具挑战性且易受催化剂毒化影响的反应提供高效的解决方案。