Atomically dispersed iron on nitrogen-decorated carbon for high-performance oxygen reduction and zinc-air batteries

Abstract

Designing low-cost oxygen reduction reaction (ORR) electrocatalysts to replace platinum group metal holds great promise for boosting the wide use of metal-air batteries. Herein, atomically dispersed iron supported on nitrogen-doped carbon (A-Fe-NC) was fabricated via an effective ligand-stabilized pyrolysis strategy. Owing to the high density of the active sites and the two-dimensional (2-D) nanosheet structure, the as-prepared A-Fe-NC electrocatalyst delivers excellent ORR performance with a positive half-wave potential of 0.865 V in alkaline solution, which is superior to that of Pt/C (0.82 V vs RHE). Moreover, the primary Zn-air battery assembled with the A-Fe-NC delivered an ultrahigh specific power of 132.2 mW cm−2 and stable long-term operation. It also displayed robust charging-discharging cycling performance with voltage gap of 0.83 V after 240 h, lower than that of the Pt/C + RuO2 electrode (0.95 V). To reveal the catalytic mechanism of A-Fe-NC, density functional theory calculation was conducted and the results revealed that the interaction between Fe and nitrogen regulated the electronic structure of active sites, thus improving charge transfer and further promoting the electrocatalytic reactivity for ORR. This work provided a facile and effective strategy for constructing Fe/N codoped 2-D carbon nanocomposite as high performance electrocatalysts for energy conversion.