Iron oxide embedded on N-Graphene is synthesized and tested by using RDE for LSV and CV measurement. I want to know the electrochemical activity of the catalyst based on ORR activity. After purging with O2 gas in 0.5M H2SO4 for 30 min, the LSV is measured at 1500 rpm. The LSV graph is plotted as in the attachment. Normally, after Onset Potential is determined, the graph is going to form plateau. I am not sure weather it is following the 2e- or 4e- pathway mechanism. As far as I concerned, determination of the ORR mechanism by using Koutecky -Levich plot which carried out at the plateau of the graph in LSV. It is confusing. Anyone can help me to explain the graph?