Sulfur,\nTrace Nitrogen and Iron Codoped Hierarchically Porous Carbon Foams\nas Synergistic Catalysts for Oxygen Reduction Reaction

Abstract

Sulfur,\ntrace nitrogen and iron codoped, hierarchically porous carbon foams\n(HPCFs) were fabricated by directly pyrolyzing sulfur-enriched conductive\npolymer, poly­(3,4-ethylenedioxythiphene)–polystyrenesulfonic\nacid (PEDOT-PSS) aerogels under argon atmosphere. This simple pyrolysis\ntreatment results in the molecular rearrangement of heteroatom sulfur,\nadjacent carbons and trace nitrogen/iron from oxidants to form active\ncatalytic sites of HPCFs. At the same time, the high porosity of HPCFs\nprovides the large surface area for the uniform distribution of active\nsites, and allows rapid oxygen transport and diffusion. As a result,\nthese HPCFs exhibit the enhanced catalytic performances for oxygen\nreduction reaction (ORR) via a direct four-electron reduction pathway\nin alkaline electrolyte. Besides, they also display a higher stability\nand better methanol/CO tolerance than the commercial Pt/C catalyst,\nwhich makes them promising low cost, non-precious-metal ORR catalysts\nfor practical application in fuel cells and metal–air batteries.