A plasma-assisted approach to enhance density of accessible FeN4 sites for proton exchange membrane fuel cells

Abstract

Enhancing the density and utilization of FeN4 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 Fe3+ but also creates additional active sites for Fe3+ loading, leading to an increase in the number of available FeN4 sites in FeNC electrocatalysts during pyrolysis. The density (76.5 μmol g−1) 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 HClO4 solution and a power density of 0.860 W cm−2 in proton exchange membrane fuel cells (PEMFCs). The developed plasma-assisted approach for improving the site density (SD) and utilization of FeN4 provides a new perspective for high-performance ORR FeNC catalysts.