A plasma-assisted approach to enhance density of accessible FeN sites for proton exchange membrane fuel cells.

Enhancing the density and utilization of FeN sites can serve as a viable approach to enhance the catalytic efficacy of iron nitrogen carbon (FeNC) catalysts for oxygen reduction reaction (ORR). Herein, we present a plasma-assisted method for enhancing the porosity of nitrogen-doped carbon. Our findings indicate that the ideal ratio of mesopore to micropore area is 0.463. This ratio not only promotes the diffusion of Fe but also creates additional active sites for Fe loading, leading to an increase in the number of available FeN sites in FeNC electrocatalysts during pyrolysis. The density (76.5 μmol g) and utilization (21.08 %) of d-FeNC-30 are significantly higher than those of FeNC without plasma treatment, with a 2.8-fold and 2-fold increase, respectively. Remarkably, it displays outstanding performance, evidenced by a half-wave potential of 0.835 V (vs. RHE) in a 0.1 M HClO solution and a power density of 0.860 W cm in proton exchange membrane fuel cells (PEMFCs). The developed plasma-assisted approach for improving the site density (SD) and utilization of FeN provides a new perspective for high-performance ORR FeNC catalysts.