A promising graphitic N-dominated porous carbon catalyst derived from lotus leaves for oxygen reduction reaction

In this work, lotus leaves are carbonized at 900 °C and yield nitrogen self-doped spongy-like porous carbons, based on a considerably cost-effective and simple approach. Through electrochemical analysis, the obtained metal-free catalyst exhibits excellent electrocatalytic performance in oxygen (O2) saturated 0.1 M KOH solution with an onset potential of 0.92 V (vs. reverible hydrogen electrode (RHE)) and half-wave potential of 0.81 V. In addition, the long-time durability and methanol resistance of obtained catalyst are much better than that of commercial Pt-C catalysts, desirable for practical applications in fuel cells. Carbonization temperature has a significant effect on the forms of nitrogen (N) species in carbon materials, which is highly related to the electrocatalytic activity toward oxygen reduction reaction (ORR). It is experimentally deduced that graphitic-N holds the key to electrocatalytic activity, and the graphitic N-dominated carbon catalyst is a promising alternative for commercial Pt-C catalysts, deserving further investigation.