Correlating oxygen reduction activity of N, S-co-doped carbon with the structures of dopant molecules

Abstract

Developing metal-free carbon electrocatalysts with atomically precise structures of hetero-doping is crucial for inventing reliable alternatives to precious metal-based catalysts. Our study reveals that the optimal active site is the edge-exposed N-neighbored carbon site in a chained N-C-C-S structure. Carbon material with N-C-C-S functional doping is controllably synthesized through polymer dehalogenation and heteroatom doping with thiomorpholine at room temperature. The resulting N/S-co-doped carbon with N-C-C-S functionalization, named N-C2-S, exhibits excellent ORR performance compared to other types of N, S-co-doped carbon, and commercial Pt/C. Typically, the N-C2-S sample shows the earliest onset potential of 0.96 V and a high half-wave potential of 0.85 V for promoting ORR. Assembled into an Al-air battery, The N-C2-S delivers an exceptional open-circuit voltage of 1.95 V and a large specific power of 128.1 mW cm2. The synthesis strategy developed in this work can potentially open up precise functionalization of synthetic carbons with heteroatoms.