A study of defect-rich carbon spheres as a metal-free electrocatalyst for an efficient oxygen reduction reaction
In this work, we report a new, economical, scalable synthetic strategy to prepare pure carbon spheres (CSs) without dopants or residual metal. The CSs gave rise to an excellent oxygen reduction reaction (ORR) performance in terms of activity and reaction kinetics. They showed particularly superior stability: there was no attenuation of the half-wave potential for CSs-20 h-900 after 13 500 cycles of CV in O2-saturated 0.1 M KOH. Our results confirmed the significant role of intrinsic defects for high-activity ORR without the need to include other dopants. The study of carbon defects shed fresh light on the true origin of the activity of metal-free ORR catalysts and is fundamentally important and technically promising for promoting the development of other original, low-cost, high-efficiency carbon-based metal-free electrocatalysts.