Improving the durability of Fe/N/C catalysts using radical scavengers

Abstract

Atomically dispersed iron-nitrogen-carbon (Fe-N-C) catalysts are promising for hydrogen fuel cells. However, they suffer from fast degradation. Here, we show that adding organic molecules with suitable properties can work as scavengers of reactive oxygen species to alleviate catalyst degradation effectively. The effects of five molecules (i.e., methanol, ethanol, isopropanol, tert-butanol, and dimethyl sulfoxide) with distinct size, viscosity, and radical scavenging speeds were systematically studied using Fe-N-C catalysts with different porous structures. High-viscosity scavengers (e.g., isopropanol, tert-butanol) comprised the catalytic activity of Fe-N-C catalysts. Marching organic molecule size with the pore structure of Fe-N-C catalysts other than their radical scavenging speed is more critical. The large size dimethyl sulfoxide, having detrimental effects on Fe-N-C-microP with abundant micropores, significantly reduces the degradation of Fe-N-C-mesoP with abundant mesopores and Fe-N-C-CB with catalytic sites on carbon black surfaces. These findings provide important insights for designing suitable scavengers to enable Fe-N-C catalysts’ long-term service.