Fig. 2: OER activity trends at the influence of alkali metal cations.

The OER activity of the Ni₆₅Fe₃₅ catalyst in purified 0.1 M XOH electrolytes (X = Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺) measured “in house”. a OER overpotential (η_OER) at 10 mA cm⁻² from steady-state conditions. b Tafel slope analysis extracted from steady-state conditions. c The anodic peak positions (E_p,a) of the Ni²⁺→ Ni^(3+δ)+ redox peak (left), and the corresponding integrated anodic peak charge (Q_p,a, right) obtained from CVs at 10 mV s⁻¹. All data in this figure was recorded using a reversible hydrogen electrode (RHE) as a reference electrode. Error bars show the standard error from the overall number of measurements.