Fig. 6: In situ Raman spectra during the OER process.

In situ Raman spectra of (a) NiFe_0.3MoO_x, b NiFe_0.3O_x, and c NiO_x obtained at OCP, staircase constant potential within 1.2–2.0 V vs. RHE (100 mV intervals), and OCP after the applied staircase potential.