Nitrogen-doped
carbon materials are realized as effective electrode
materials for oxygen-involved electrochemical devices. Understanding
of active sites for adsorption of oxygen molecules is of significant
importance for the development of carbon-based electrode materials.
Herein, we synthesize two model catalysts named carbon-covered nitrogen-doped
hollow carbon nanoparticles and nitrogen-doped carbon-covered hollow
carbon nanoparticles by pyrolysis of block copolymer brushes to investigate
the active sites for the adsorption of oxygen molecules. The electrocatalytic
performance for oxygen reduction reaction (ORR) and carbon dioxide
adsorption suggest that carbon atoms are Lewis basic active sites
for oxygen adsorption. The coverage of a thin carbon layer on nitrogen-doped
carbon materials can increase the surface density of Lewis basic sites
for oxygen adsorption and can accordingly improve the electrocatalytic
activity toward ORR as confirmed by a positive shift of both onset
potential and half-wave potential.