▎ 摘　　要

The oxygen reduction reaction (ORR) is of key importance in the field of electrochemical energy production. Remarkable catalytic properties of metal-free graphene nanoribbons towards the ORR were suggested in previous reports. Herein, we show that the electrocatalytic properties of an undoped supposedly metal-free graphene nanoribbon towards the ORR is actually caused by metallic impurities within the graphene nanoribbons.