Metal-free N-doped carbon blacks as excellent electrocatalysts for oxygen reduction reactions

Electrochemical oxygen reduction reactions (ORRs) require efficient, durable, and cost-effective electrocatalysts. In this regard, the development of metal-free catalysts with excellent activity is essential. Herein we report the development of a novel two-step heating route to produce metal-free N-doped carbon blacks. The prepared materials exhibit superior electrocatalytic performance for ORRs in a basic media, which is comparable to commercial Pt/C catalysts. Among the various heating temperatures tested, sequential two-step heating at 750 and 1000 °C produced the most efficient catalysts with onset and half-wave potentials of 0.97 and 0.82 V, respectively. The prepared materials show excellent selectivity for 4-electron transfer, durability, and stability in response to methanol poisoning. Control experiments with one-step heating and no N-doping confirm the superiority of the two-step heating process for producing efficient electrocatalysts.