N,S-Codoped Carbon Shells Embedded with Ultrafine Co NPs for Reductive Amination with Formic Acid

Herein, N,S-codoped carbon materials embedded with ultrafine and well-distributed Co nanoparticles (1.14 wt % Co) were prepared through pyrolysis of the hybrids of SNW-1 and Co(Ac)(2) coated with glucose. It was observed by TEM and XRD that Co nanoparticles (NPs) were entrapped in doped carbon shells uniformly. The glucose coating presented a significant impact on the size distribution of Co NPs and doped modes of heteroatoms, especially the S species. The catalyst displayed outstanding activity for catalytic transfer hydrogenation (CTH) with formic acid under the base-free system. Encouragingly, diverse secondary amines were produced in excellent yields through the domino reaction of hydrogenation and reductive amination. Remarkably, the catalyst with ultrafine Co NPs showed good durability under harsh reaction conditions and displayed no significant loss in both activity and selectivity in 5 runs. This was attributed to the protection of constructed N,S dual-doped carbon shells. Hence, we offer an alternative strategy for the construction of dual-doped carbon materials trapped with ultrafine transition metal, which can be further applied in various catalytic processes.