Trifunctional Co nanoparticle confined in defect-rich nitrogen-doped graphene for rechargeable Zn-air battery with a long lifetime

Rationally designing an efficient and stable multifunctional electrocatalyst to replace the noble metal catalysts is extremely demanding but challenging. Herein, we develop a facile method to synthesis the defective nitrogen-doped graphene encapsulated metal nanoparticles by pyrolysis of graphene-supermolecule complexes. The obtained catalyst exhibits superior activities toward ORR (E-1/2 = 0.864 V), OER (eta =383 mV@10 mA/cm(2)) and HER (eta = 193 mV@10 mA/cm(2)) in 0.1 M KOH solution. Equipping the materials into a rechargeable zinc-air battery produces a peak power density of 205 mW/cm(2) and a cycle life of 667 h. It is found that formative M-N-x and defective N-doped graphene are the main origins of ORR activity while OER and HER activities are attributed to the defect-rich N-doped C and Co core. This finding provides insights to design electrocatalyst with both multifunctional catalytic activities and high stability.