Synergistically enhanced oxygen reduction activity of iron-based nanoshell carbons by copper incorporation

This study reports the synergistic improvement of the oxygen reduction reaction (ORR) activity of a carbon catalyst prepared from a phenol-formaldehyde resin by simultaneous incorporation of Cu and Fe phthalocyanines. This carbon catalyst exhibited higher ORR activities than those prepared with either Cu or Fe phthalocyanines, with an approx. 28-fold maximum ORR current enhancement observed when Cu/Fe = 75:25 was incorporated into the carbon precursor. Surface and structural characterizations of these catalysts suggested that the incorporated Cu played a role in suppressing the catalytic activity of Fe, forming the reported nanoshell structure, and in keeping more nitrogen atoms attached to carbons. The incorporation of Cu in the carbon catalyst provided a doping effect for nitrogen into the carbon structure and inhibited catalytic graphitization caused by Fe species. These effects resulted in a distinctive carbon structure in the nanoshell. These multiple effects of Cu incorporation were considered key factors in the enhancement of ORR activity caused by Fe and Cu incorporation.

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