Cobalt embedded in N-doped carbon for aerobic oxidation of hydroquinone in water

When air or oxygen is used as the oxidant, highly active non-noble metal catalysts are in urgent demand for the oxidation of hydroquinone (HQ), a typical phenolic environmental pollutant, in water. Herein, cobalt nanoparticles embedded in N-doped carbon (Co@CN) catalyst were prepared by a one-step approach, which showed a high turnover frequency of 228.9 h -1 in aerobic oxidation of HQ at 25 o C, exceeding reported heterogeneous catalysts. Encapsulated metallic cobalt is responsible for the catalytic activity, and the appropriate N species doping can facilitate this process. The Co@CN could be recovered by simple separation and reused 5 times without obvious deactivation. Besides, it exhibited excellent effects on the oxidation of varied HQ derivatives in methanol. This work proposes a novel green method for aerobic oxidation of HQ in water, which has potential application prospects in wastewater treatment. • Air or oxygen as oxidant, water as solvent. • A green new method for aerobic oxidation of hydroquinone. • The cobalt embedded in N-doped carbon was a key factor. • The catalyst showed good recovery and stability.