Fig. 5: Identification of acidic OER mechanism.

a Complex capacitance plots (C′: the real capacitance represents the ability of the system to store electrical energy and C″: the imaginary capacitance indicates losses in the form of energy dissipation.) as a function of potential for Ru_(SA)-OMS and Ru_(SA)-NiOMS at a low frequency (10⁻¹Hz). Operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) recorded in the potential range of 0.90–2.40 V versus RHE for b Ru_(SA)-OMS and c Ru_(SA)-NiOMS. d Schematic illustration of the operando electrochemical mass spectrometry (DEMS). DEMS signals of ³²O₂, ³⁴O₂, and ³⁶O₂ from the gaseous products for ¹⁸O-labeled e Ru_(SA)-OMS and f Ru_(SA)-NiOMS.