Catalyst-free growth of large scale nitrogen-doped carbon spheres as efficient electrocatalysts for oxygen reduction in alkaline medium

Nitrogen-doped carbon spheres (NCS) are synthesized by directly pyrolyzing a nebulized solution of xylene and ethylenediamine via a spray pyrolysis method, without using a catalyst. X-ray photoelectron spectroscopy (XPS) measurements confirm that the NCS only contain C, N and O. The electrocatalytic performances show that the NCS exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction (ORR) in an alkaline medium. This study successfully develops a new non-precious metal catalyst, which exhibits an excellent electrocatalytic performance, using a simple, cost-effective and scalable method. It also provides an increased fundamental understanding in the origins of ORR activity enhancements using N-doped carbon materials.

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► NCS were directly synthesized via a spray pyrolysis method without using a catalyst.
► Spray pyrolysis method is a simple, cost-effective and easy scale-up method.
► The NCS catalyst can exhibit excellent catalytic activities, long-term stability, and a high methanol tolerance.