In metal-air batteries, heteroatom-doped carbon catalysts have been widely regarded as promising substitutes for Pt-based catalysts for enhancing oxygen reduction reaction (ORR) performance owing to their excellent catalytic activity and low cost. Sulfur (S) is a potential heteroatom dopant. However, its large atomic radius causes limitations, such as edge-selective doping and low doping amount. Herein, we report a successful fabrication of edge-enriched S-doped carbon nanoflakes (ESCNs) with S doping amount as high as 6.04 at% by chemical vapor deposition (CVD) method using thiophene as carbon/sulfur source and basic magnesium carbonate (BMC) nanoflake as template. The as-obtained ESCNs are highly porous with well-crystallized graphite layers on the edge and possess a large specific surface area of 1,306 m2 g-1, resulting in remarkable ORR catalytic performance under alkaline condition. The ORR yields a high current density of 7.0 mA cm-2 at -0.03 V (vs. RHE) and outstanding durability. When applied in zinc-air batteries, the as-developed ESCNs demonstrate superior electrochemical performance under different discharge current densities.
Keywords Heteroatom doping, Chemical vapor deposition, Template synthesis, Edge exposure, Zinc-air battery