Cobalt Encapsulated in N-Doped Graphene Layers: An Efficient and Stable Catalyst for Hydrogenation of Quinoline Compounds

Abstract

Porous nitrogen-doped graphene layers encapsulating cobalt nanoparticles (NPs) were prepared by the direct pyrolysis process. The resulting hybrids catalyze the hydrogenation of diverse quinoline compounds to access the corresponding tetrahydro derivatives (THQs), important molecules present in fine and bulk chemicals. Near-quantitative yields of the corresponding THQs were obtained under optimized conditions. Notably, various useful substituted quinolines and other biologically important N-heteroarenes are also viable. The enhanced stability of the catalyst is ascribed to the encapsulation structure, which can enormously reduce the extent of leaching of base metals and protect metal NPs from growing larger. The achieved success in the encapsulation of metal NPs within graphene layers opens an avenue for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.

Scalable and controllable synthesis of atomic metal electrocatalysts assisted by an egg-box in alginate

“…14,26 However, the metal nanoparticles (NPs) are often encapsulated by graphitic carbon layers, forming dense core-shell structure, thus protecting the NPs from acid washing, thus it is highly impossible to obtain a fully atomic metal catalyst. [27][28][29][30] Accordingly, it is necessary to generate porous channels in the graphitic carbon layers to enable acid accessible to those encapsulated metal NPs. This idea has been confirmed feasible by electrochemical activation 31 , but the activation process is very time-consumable.…”

Olefin‐Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations

“…The catalyst solution obtained from anthracene, CoBr 2 , and LiEt 3 BH proved to be very stable and showed no loss of catalytic activity after storage for several hours at room temperature. Extensions of this methodology to the hydrogenation of polar C=X bonds such as ketones, imines, and quinolines, resulted in very good yields of the desired alcohols and amines (Scheme ). While the activity of the ternary catalyst mixture anthracene/CoBr 2 /LiEt 3 BH is comparable to recent literature methods, this protocol exhibits much higher operational simplicity as no complex ligand or pre‐catalyst is required and the catalyst preparation operates in situ by simple mixing of the components at room temperature prior to hydrogenation.…”

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

“…So, for the synthesis of graphene–NP hybrid systems, in most cases, top-down approaches have been used. Different architectures of graphene–NP hybrids can be prepared by this one-pot synthesis method [71]. In another process for the synthesis of graphene–NP hybrids, graphene or NPs could be chemically functionalised firstly and then NPs could be conjugated to the graphene surface by covalent or noncovalent interaction [72–73].…”