Synthesis of 3D N, S Dual-Doped Porous Carbons with Ultrahigh Surface Areas for Highly Efficient Oxygen Reduction Reactions

Graphical Top performer : A novel method is explored to synthesize 3D N, S dual-doped porous carbons. The surface area, porosity, and surface chemistry can be tuned by heat temperature. The oxygen reduction reaction (ORR) catalysis of the as-prepared porous carbon outperforms most previously reported metal-free catalysts. The samples show high activity for the ORR, good capacitive performance, and excellent tolerance to the high concentration of methanol. Replacing rare and expensive metal electrocatalysts with efficient, low-cost, and stable ones for the oxygen reduction reactions (ORR) is of significant importance. Herein, we report a novel scalable synthesis of three-dimensional (3D) N, S dual-doped porous carbons (NSPCs) with ultrahigh surface areas that can serve as highly active, metal-free electrocatalysts for the ORR. The NSPCs are prepared by synthesizing 3D black pillar foams from a mixture containing p-nitroaniline and concentrated sulfuric acid, and subsequently carbonization under an Ar atmosphere. This method not only avoids the use of any template, but also allows for the simultaneous optimization of both porous structures and surface functionalities by tuning the carbonization temperature. Owing to the synergy of the tailored porous structure and N, S dual-doping, the NSPC pyrolyzed at 1000 °C exhibits a good catalytic activity toward the ORR with a half-wave potential of −0.10 V vs. Ag/AgCl and a high four electron (4e − ) oxygen reduction selectivity in an alkaline medium, which is identical to that of the commercial 20 wt% Pt/C catalyst, and outperforms most previously reported metal-free catalysts. The NSPCs also show good energy-storage performance for advanced supercapacitors.