Scalable nitrogen-enriched porous sub-100 nm graphitic carbon nanocapsules for efficient oxygen reduction reaction in different media

Abstract

The oxygen reduction reaction (ORR) is deemed a sustainable energy source; however, developing green, earth-abundant, and efficient noble-metal-free catalysts for efficient ORR in different media remains a grand challenge. Herein, we present a scalable, facile, environmentally benign, and one-pot strategy for the fabrication of eco-friendly nitrogen-enriched graphitic-like hierarchical porous sub-100 nm carbon (denoted as N-HMPC) nanocapsules with controllable N-content for ORR. The synthesis route is based on in situ organic-organic self-assembly of Pluronic F127 copolymer micelles and resorcinol-melamine-formaldehyde in the presence of a silica template followed by carbonization and eroding the silica core. The as-formed N-HMPC nanocapsules have a core-shell morphology (∼84 nm), hierarchical porosity, high surface area of (790 m2 g−1), and tunable nitrogen content (9-25%). Intriguingly, N-HMPC nanocapsules exhibit an analogous ORR activity to the commercial Pt/C catalyst (20% Pt) in the alkaline and acidic electrolytes, besides superior durability and inimitable tolerance to methanol and CO poisonings due to the hollow core-shell architecture and abundant nitrogen. A judicious combination of experimental and density functional theory (DFT) simulations delineated the ORR pathway and mechanism for N-HMPC in acidic and alkaline electrolytes. The presented approach may open new avenues for the rational design of metal-free green electrocatalysts for ORR.