Boosting the oxygen reduction reaction using high surface area graphitic-N dominant nitrogen doped carbon

Abstract

A highly active, durable, and economical catalyst towards the oxygen reduction reaction (ORR) is the need of the day because of the scarce nature, high price, and meager stability of Pt/C, which is nowadays used as an efficient cathode catalyst for fuel cells. In this work, a ZIF-8-derived nitrogen doped carbon catalyst (NC-1000) with a high graphitic-N (52.4%) content, high surface area (3492 m² g⁻¹) and diverse porous 3D network structure is prepared by using a double pyrolysis strategy. In O₂-saturated 0.1 M KOH solution, it shows significantly improved ORR performance with high onset potential (1.016 V vs. RHE) and half-wave potential (0.898 V vs. RHE), small Tafel slope (38.5 mV dec⁻¹), and high limiting current density (−6.25 mA cm⁻²), justifying the fast charge transfer kinetics and high activity. This material also confers high ORR selectivity via the 4e⁻ pathway and excellent stability/durability after either continuous chronoamperometric operation or the accelerated stress test. The ORR performance of NC-1000 is better than that of most of the previously reported nitrogen doped carbon catalysts, and the as-prepared NC-1000 is among the best catalysts for the ORR in an alkaline environment. Moreover, it was confirmed with DFT calculations that graphitic-N species are mainly responsible for the excellent ORR performance of NC-1000 following the associative mechanism.