For Rh-modified Ni-poly, HOR measurements were done immediately after the galvanic displacement and after 25 cycles between 0 and 1.2 V vs. RHE, i.e., electrochemical cleaning of the electrode surface. Measurements were done in H2-saturated 0.1 mol dm -3 solution using the RDE technique, and the potential sweep rate was 10 mV s -1 . After the HOR measurements, the electrolyte was purged with N2, and the electrode was extensively cycled. When a stable cyclic voltammogram was obtained, the blank cyclic voltammogram (background) was recorded between 0.05 and 1.0 V vs. RHE. Then, the electrolyte was saturated with O2, and the ORR polarization curves were recorded using the RDE technique. The potential sweep rate was 20 mV s -1 .