aat the current density of 1 μA cm−2 (electrochemically active surface area). bbased on the geometrical surface area. c0.7–0.75 V. d0.55–0.65 V. ebased on the electrochemically active surface area. fmeasured by hydrodynamic voltammetry at room temperature (22°C). gmeasured by linear sweep voltammetry at (30°C). hestimated by extrapolating the Tafel slope. iwith a slight mass-transfer limitation.