Figure 4

Electrochemical analysis results: (a) Linear sweep voltammograms (LSVs) and (b) Tafel plots of the PtFex/C samples and Pt/C measured in an O2-saturated 0.1 M HClO4 electrolyte. (c) Specific activity (jk, kinetic current density) and (d) specific mass activity (jmass) estimated from the LSVs. The jk and jmass data are normalised by the electrochemical surface areas (ESAs) obtained by integration of the Hupd region in cyclovoltammograms (CVs).