The preparation of efficient and recyclable solid catalysts exhibiting high activity and selectivity toward the target product is a prerequisite to enhance the overall efficiency of a catalytic process. Herein, we study a series of Fe/Fe₃C-containing nitrogen-doped porous carbon microspindles (Fe/Fe₃C@NC–x, where x stands for the pyrolysis temperature), which are core-/shell-structured hybrids, constructed by the pyrolysis of a metal–organic framework precursor as highly selective catalysts for the oxidation of sulfides to the corresponding sulfoxides under mild conditions. The Fe/Fe₃C@NC–x microspindles comprising Fe and Fe₃C nanocrystals inlaid in nitrogen-doped porous carbon shells are fabricated by the direct carbonization of NH₂–MIL–88B(Fe) polyhedra at 500 °C–800 °C and under nitrogen atmosphere. Among the various investigated catalysts, the Fe/Fe₃C@NC–600 microspindles exhibit the best catalytic activity, higher than those exhibited by the analogue Fe/Fe₃C@C–600 without N doping and the commercial Fe₂O₃, Fe₃O₄, and Fe₃C used for the catalytic oxidation of sulfides owing to the synergistic contribution of the Fe₃C sites and adequate nitrogen doping in the porous carbon support. Furthermore, the magnetically separable properties of the Fe/Fe₃C@NC–600 microspindles enable their convenient isolation from the reaction system using an external magnet, and they can be repeatedly used for six cycles without any loss in catalytic efficiency.

制备对目标产物具有高活性和选择性的高效可循环使用的固体催化剂是提高催化过程总体效率的前提。在这里，我们研究了一系列含Fe / Fe ₃ C的氮掺杂多孔碳微主轴（Fe / Fe ₃ C @ NC–x，其中x代表热解温度），它们是核/壳结构的杂化体，通过金属-有机骨架前体的热解而构建的，作为在温和条件下将硫化物氧化为相应亚砜的高度选择性催化剂。Fe / Fe ₃ C @ NC–x微锭包含Fe和Fe ₃ C纳米晶体，镶嵌在掺杂氮的多孔碳壳中，是通过NH的直接碳化制得的₂ –MIL–88B（Fe）多面体在500°C–800°C和氮气氛下。在各种研究过的催化剂中，Fe / Fe ₃ C @ NC-600微锭表现出最好的催化活性，高于没有掺杂N和商业用Fe ₂ O ₃的类似Fe / Fe ₃ C @ C–600所表现出的那些。由于Fe ₃ C位点的协同作用和多孔碳载体中足够的氮掺杂，Fe ₃ O ₄和Fe ₃ C用于硫化物的催化氧化。此外，Fe / Fe ₃的磁分离特性C @ NC–600微主轴可使用外部磁体方便地与反应系统隔离，并且可以重复使用六个循环而不会降低催化效率。