NaCl protected synthesis of 3D hierarchical metal-free porous nitrogen-doped carbon catalysts for the oxygen reduction reaction in acidic electrolyte.

A high-performance 3D hierarchical porous metal-free N-doped carbon catalyst toward the oxygen reduction reaction (ORR) in acidic medium was successfully synthesized by employing ZnO as a mesoporous template and NaCl as both a macroporous template and a structure protective agent. The resultant improved active site density and diffusion efficiency lead to a superior ORR activity with a half-wave potential high up to 0.755 V in 0.1 M HClO4.