Fig. 2: Surface-confined Fe sites via chronoamperometric (CA) metal-ion-spiking. | Nature Communications

Fig. 2: Surface-confined Fe sites via chronoamperometric (CA) metal-ion-spiking.

From: Cooperative Fe sites on transition metal (oxy)hydroxides drive high oxygen evolution activity in base

Fig. 2

CA measurements of a NiOOH and c CoOOH at 1.55 V vs. RHE. After starting the measurement in purified Fe-free 1.0 M KOH electrolyte, aqueous Fe(NO3)3 was added to a concentration of 0.1 ppm. The first voltammetry cycle (red, 10 mV/s) after Fe-spiking CA measurements shows the dramatic effect of Fe incorporation on the OER activities of NiOxHy (b) and CoOxHy (d), but a minimal effect on the redox wave compared to the light green lines that show the initial voltammetry (cycle two) recorded in purified Fe-free 1.0 M KOH. The grey curves illustrate the large effect on the redox wave position for NiOxHy but not for CoOxHy after cycling, but that the OER activity does not further change much. The data is not iRu compensated. The cartoons illustrate schematically the process intentionally without atomic detail that is yet unknown.

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