Plasma-Modified FeGly/C as a Pt-Free Stable ORR Electrocatalyst in an Acid Electrolyte

Abstract

Plasma-assisted synthesis of M–N–C catalysts has a strong positive role in enhancing oxygen reduction reactions (ORRs). Very recently, we showed that plasma changes the surface property of the support and promotes ORR of M–N–C catalysts. We extended this research by studying and comparing the effects of several plasma sources, for example, N2, NH3, and O2, on a pyrolyzed FeGly/C catalyst and observed that N2-plasma-treated FeGly/C (N-FeGly/C) is a superior ORR catalyst. Experimentally, it shows that plasma improves the electrochemical capacitance 8.5 times. Powder X-ray diffraction, along with X-ray photoelectron spectroscopy analysis, suggests that the supported carbon contains more heteroatomic defects with ORR-active FeNx sites. N-FeGly/C shows a higher ORR onset (0.80 V), lower peroxide yields (4.0% at 0.20 V/RHE and 11.4% at 0.70 V/RHE), and improved structural stability compared to FeGly/C, on account of improved surface hydrophilicity with more O2 adsorption centers. Plasma-assisted incorporated nitrogen at the carbon support could modify the local electronic environment for effective oxygen adsorption and shows high stability even after 10,000 potential cycles. Thus, this research may be a promising alternative to conventional ORR catalysts for long-term applications such as low cost and active cathode catalysts for fuel cell research.