Fig. 3: Catalytic performance for the HOR.
a, HOR polarization curves recorded on Ni@C-MoOx, NiMoOx and 20 wt% Pt/Ccom electrodes in H2-saturated 0.1 M KOH electrolyte; data were obtained using a rotating disk electrode at a rotation rate of 2,500 rpm with a potential scan rate of 5 mV s−1. b, Cyclic voltammograms recorded on the Ni@C-MoOx electrode in H2- and N2-saturated 0.1 M KOH electrolyte; data were obtained using a rotating disk electrode at a rotation rate of 1,600 rpm with a potential scan rate of 5 mV s−1. c,d, Chronoamperometry curves recorded on Ni@C-MoOx- and NiMoOx-coated GDEs in H2-saturated 0.1 M KOH at 0.3 VRHE (c) and 0.7 VRHE (d). The NiMoOx catalyst totally lost its activity for the HOR within 0.2 hour, and the break in the x-axis in (c) shows the details of current decline in the stability test of NiMoOx catalyst at 0.3 VRHE. e,f, Ni 2p3/2 XPS spectra of Ni@C-MoOx (e) and NiMoOx (f) catalsyts before and after subjected to the step-potential stability test, where the satellite peak (Sat.) of Ni 2p3/2 and the KLL auger peak of F (F KLL) from ionomer were present (Methods provide fitting details).
