Highly crumpled nanocarbons as efficient metal-free electrocatalysts for zinc-air batteries.

The rational design of an efficient and robust oxygen reduction reaction (ORR) electrocatalyst is vital for energy conversion and storage systems, especially for metal-air batteries. Herein, we report a highly nanocrumpled and nitrogen, phosphorus-codoped nanocarbon (NC-NPC) synthesized by direct pyrolysis of melamine and triphenylphosphine. With the rich nano-crumpled structure and codoping of heteroatoms, this low-cost catalyst exhibits an excellent ORR performance, and possesses a half-wave potential of 0.84 V vs. RHE, a small Tafel slope of 70.2 mV dec-1, and good electrocatalytic stability. More importantly, it can also be applied in zinc-air batteries as an efficient electrode which delivers an open-circle voltage of 1.38 V, a specific capacity of 782 mA h gZn-1, and a long cycling life of 210 h, superior to the commercial Pt/C catalyst.