Lettuce–like, Hierarchically Porous and Nitrogen-Doped Carbon Catalyst: As a Superb non-Precious-Metal Oxygen Reduction Reaction Electrocatalyst in both Alkaline and Acidic Media

A new kind of N-doped, hierarchically porous carbon catalyst (NHPC) derived from N-rich space network polymers coupled with plenteous metal-coordination sites was designed and controllably synthesized by exploiting nano-SiO2 as a hard-template and pyrolyzing strategy. The characterization result demonstrates that NHPC pyrolyzed at 900 oC exhibits a hierarchically lettuce-like architecture with high surface area (2112 m2 g−1). Remarkably, the porosity structure and specific surface area (SSA) can be accessibly tailored by adjusting the density of porosity. Furthermore, the electrocatalytic activity are strongly dependent on these properties. Benefiting from the balance of high SSA, channel structures, chemical compositions and conductivity, NHPC obtained at 900 oC shows high active for oxygen reduction reaction (ORR), along with excellent durability, equivalently performing the advanced Pt/C catalyst in both alkaline and acidic circumstance. The onset and half-wave potentials of NHPC-1:0.25-900 display 0.97 and 0.86 V vs RHE for onset potential and half-wave potential in alkaline medium, together with 0.85 and 0.69 V vs RHE in acidic medium.