Rational synthesis of N/S-doped porous carbons as high efficient electrocatalysts for oxygen reduction reaction and Zn-Air batteries

Abstract

The development of efficient and low cost electrocatalysts for oxygen reduction reaction (ORR) to replace precious metal-based catalysts is one of the emerging issues for wide applications of fuel cells and metal-air batteries. In order to develop better catalysts for ORR and study the effect of co-doping, in this work, we prepared S/N co-doped porous carbons by using commercially available monomers and the radical polymerization method. Besides, silica sphere hard template was also used to prepare porous carbons with hierarchical porous structure. Sulfur blending and ammonia activation were used to rational control the S/N ratios for the porous carbons. The as-prepared S/N doped porous carbons exhibit high specific areas up to 681 m2/g, high N and S contents up to 4.9% and 0.9%, respectively. As electrocatalysts in alkaline media, these porous carbons show high ORR activity with half wave potential up to 0.825 V vs. RHE, electron transfer number of 3.9 and good tolerance to methanol. As air cathode for Zn-air batteries, these porous carbons show peak power density of 10.7 mW cm−2 at 17.4 mA cm−2. This work indicates that great potential of S/N -doped carbons as high efficient electrocatalysts for ORR and Zn-air batteries.