Heterogenization of cobalt nanoparticles on hollow carbon capsules: Lab-in-capsule for catalytic transfer hydrogenation of carbonyl compounds

•A “Cheap and simpler” non-precious cobalt nanoparticle (Co NPs) on hollow carbon capsules (HCCs) was synthesized.•The catalyst Co NPs@HCCs was utilized for transfer hydrogenation of carbonyl compounds with good yield and TON.•This catalytic system does not require additives for activation and proceeds readily with mild reaction conditions.•It may open the way towards design of NPs incorporated structures with an adept matrix and can function as delivery agents.