F127-assisted preparation of FeCo nanoalloys encapsulated in nitrogen-doped carbon for efficient oxygen reduction reaction

Abstract

Exploring cost-effective electrocatalysts for the oxygen reduction reaction (ORR) is a prerequisite, yet a challenge for many energy conversion and storage systems. The direct pyrolysis of zeolitic imidazolate framework (ZIF) materials has been widely adopted to prepare metal–nitrogen–carbon (M–N–C) catalysts for the ORR, but they suffer from structure collapse and reduced active sites. Herein, for the first time, a novel F127-assisted ZIF-67 (ZIF-67–F127) pyrolysis strategy to construct FeCo nanoalloys encapsulated in nitrogen-doped carbon electrocatalysts Fe_xCo@NC–F127 (x represents the molar ratio of Fe to Co) was reported. The introduction of F127 into ZIF-67 endowed Fe_0.5Co@NC–F127 with a high surface area, rich mesopores, and a defective structure, thus favoring the dispersion of active sites, mass transfer and electron transport, and electronic structural regulation of M–N sites as compared to the F127-free counterpart (Fe_0.5Co@NC). As a result, the Fe_0.5Co@NC–F127 catalyst exhibited higher electrocatalytic activity for the ORR than Fe_0.5Co@NC and single metal counterparts, which was comparable to that of the commercial Pt/C catalyst. Our catalyst was demonstrated to have long-term durability and methanol-tolerance properties, which made it promising for large-scale applications. Our work provides a novel and facile strategy to fabricate platinum-free and efficient ORR catalysts.