cules 2020, 24, x FOR PEER REnetic properties of Naf-1100 and Aq-825 in H2/air a) activation overpotential against current density in Tafel region at different RHs b) specific activity at 0.85 V from this work, park et al [29], Kodama et al [7] in liquid electrolyte c) specific activity at activation overpotential of 120 mV and at different RHs.