Significant Contribution of Intrinsic Carbon Defects to Oxygen Reduction Activity

While the field of carbon-based metal-free electrocatalysts for oxygen reduction reaction (ORR) has experienced great progress in recent years, the fundamental issue of the origin of ORR activity is far from being clarified. To date, the ORR activities of these electrocatalysts are usually attributed to different dopants, while the contribution of intrinsic carbon defects has been explored little. Herein, we report the high ORR activity of the defective carbon nanocages, which is better than that of the B-doped carbon nanotubes and comparable to that of the N-doped carbon nanostructures. Density functional theory calculations indicate that pentagon and zigzag edge defects are responsible for the high ORR activity. The mutually corroborated experimental and theoretical results reveal the significant contribution of the intrinsic carbon defects to ORR activity, which is crucial for understanding the ORR origin and exploring the advanced carbon-based metal-free electrocatalysts

Alcohol-Tolerant Platinum Electrocatalyst for Oxygen Reduction by Encapsulating Platinum Nanoparticles inside Nitrogen-Doped Carbon Nanocages

Pt-based electrocatalysts are the most popular for direct alcohol fuel cells, but their performances easily deteriorate for the oxygen reduction reaction (ORR) at the cathode because of the alcohol crossover effect. Herein, we report the novel Pt electrocatalyst encapsulated inside nitrogen-doped carbon nanocages (Pt@NCNC), which presents excellent alcohol-tolerant ORR activity and durability in acidic media, far superior to the Pt counterpart immobilized outside the nanocages (Pt/NCNC). The superb performance is correlated with the molecule-sieving effect of the micropores penetrating through the shells of the nanocages, which admit the small-sized oxygen and ions but block the large-sized alcohols into the nanocages. This mechanism is confirmed by examining the size dependence of ORR and alcohol oxidation activities by regulating the micropores sizes. This study provides a promising strategy to develop the superior alcohol-tolerant Pt-based ORR electrocatalyst in acidic media