Kinetics of oxygen reduction reaction on nanostructured thin-film platinum alloy catalyst

► Nanostructured thin-film ternary PtCoMn cathode catalyst. ► Pressure and relative humidity dependence of oxygen-reduction reaction kinetics. ► 39.5 kJ mol−1 activation energy for ORR kinetics. ► 0.13-0.25 A mgPt−1 mass activity at 0.9 V, 1 atm H2 and O2, 80 °C and 100% RH. ► 1.7-2.0 mA cmPt−2 specific activity at 0.9 V, 1 atm H2 and O2, 80 °C and 100% RH.