Here we see that the activity increases with the amount of Rh deposited on the electrode, but the effects of surface oxidation are also more prominent in that case. Thus, Ni|Rh interface could be the key for a high HER activity, while Rh sites could serve as Hads acceptors where the H2 formation is taking place, as the Rh surfaces provide much better Hads energetics than Ni surfaces. However, the influence of oxides could be present even in the case of pure Rh phase, as previously shown , suggesting that the kinetics of Rh oxide reduction has a significant impact on the catalytic activity. After exposing the electrodes to high anodic potentials (1.45 V vs. RHE), a wide cyclic voltammogram was recorded to probe HER and OER activity, that is to determine the overall water- splitting voltage on the studied electrodes (Figure , left). The cycle started in the cathodic direction, thus, HER was probed first, and then OER was tested. Overpotentials for HER (ηHER,10, Table , oxidation4) and OER (ηOER,10, Table ) were extracted from this cyclic voltammogram. Further, Tafel slopes were evaluated (Table ). To evaluate Tafel slopes, a single current decade, from |2| to |20| mA cm -2 was fitted using a linear fit (Figure , right). In this way, both HER and OER overpotentials were high enough for the fitting, while gas bubbles formation was not as high to cause partial electrode surface blockage.