Under negative potentials corresponding to HER, Rh2O3 gets more reduced, but the negative impact of surface oxidation on the HER activity also suggests that the semiconducting oxide phase could be partially present even at very negative potentials, despite only metallic phase being thermodynamically stable under such conditions . This is justified by the more pronounced (negative) impact of surface oxidation on the surface with a higher Rh content (Figure , middle versus bottom row). On the other hand, RhO2, which is stable under high potential, is likely to be present during OER. This oxide is formed by the oxidation of Rh2O3 which means that the Rh phase converts from semiconducting to metallic one. Thus, OER activity is not impeded, while the OER activity of RhO2 is expected to be very high . In this way, by modifying the Ni-poly surface with Rh, high HER and OER activities were obtained, while the same surface underperforms in HOR and ORR compared to Pt-poly. Finally, considering the use of Rh in electrocatalysis, the main obstacle is its price. Rh is one of the most expensive noble metals, with a price of 130.3 EUR per gram (after even five successive depreciations within the last year ). This is much higher compared to Pt (29.3 EUR per gram), but less than iridium (148.9 EUR per gram) which is practically the only metal that is considered viable for PEM electrolysis anodes . Moreover, based on preliminary testing, the rapid galvanic displacement using platinum solution under identical conditions does not lead to appreciable catalytic activity improvements comparable to the case of Ni modification by Rh. Thus, optimizing Rh deposition to minimize its usage and restricting to the surface modifications of low-cost substrates could be a plausible route for designing novel high-performance alkaline electrolysis catalysts leading to tremendous energy saving. These savings could even justify the use of more expensive metals. However, in order to make more concrete conclusions regarding this possibility, it is necessary to consider factors beyond electrocatalytic performance.