plots in different electrolytes. Co*- and Co**-Black were
prepared by drop-casting 250 mM Co(NO3)2/ethanol
precursor on Co-Black, followed by annealing in 5% H2/Ar
at 450 °C for 30 min. CoOx/Ti was
prepared by the same procedure except that a Ti plate was used as
the supporting substrate. The Co loading was 2.1 μmol cm–2 for Co*-Black and 4.2 μmol cm–2 for Co**-Black and CoOx/Ti.