Figure 3. Comparison among kinetic properties of af-1100 and -825 i 2/ ir (a) activation overpotential against current density in Tafel region at different RHs (b) specific activity at 0.85 V from this wo , park et al [29], Kodama et al [7] in liquid lectrolyte (c) specific activity at activation overpotential of 120 mV and at different R s.