Fig. 1: Electrocatalytic performance towards the oxygen evolution reaction of NiFe0.3Ox and NiFe0.3MoOx.

a iR-corrected polarisation curves. b Tafel slope. c Nyquist plot evaluated at 1.6 V vs. RHE, and its equivalent circuit diagram. iR-corrected polarisation curves of (d) NiFe0.3MoOx, and e NiFe0.3Ox after 15 CVs, after 1000 CVs (1.2–2.0 V vs. RHE, 100 mV s−1), and after 24 h CA test. f Current response of NiFe0.3MoOx (NiFe0.3Ox) when applying a constant potential needed to reach a current density of 20 (10) mA cm−2 for 24 h.