Synthesis of 3D N-doped graphene/carbon nanotube hybrids with encapsulated Ni NPs and their catalytic application in the hydrogenation of nitroarenes

Carbon-based materials are a popularly-used catalyst support due to their large surface area, high stability, and easy accessibility for reactants, but metal NPs on carbon are prone to sintering and leaching due to weak metal-support interactions. In this work, a 3D carbonaceous material composed of 1D carbon nanotubes sprouting from 2D graphene sheets (denoted Ni@N-CNTs-GS) was synthesized via the direct pyrolysis of mixed agar, melamine, and Ni(en)(3)(NO3)(2). Characterization indicated that the newly formed CNTs were rooted in and anchored by the graphene sheets, and carbon film-encapsulated Ni NPs were dispersed evenly both in the chambers of the CNTs and on the surface of the graphene. It was found that Ni@N-CNTs-GS was active and stable for the selective hydrogenation of nitroarenes to anilines via a direct route.