Fig. 5: Operando ATR-SEIRAS and DEMS measurements.

Schematic illustration a of in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS, Internal reflection mode). Operando ATR-SEIRAS measurements in the range of 1000−1400 cm−1 at various applied potentials for (b) LaIr-Co3O4 and (c) Ir-Co3O4, all potentials were normalized against reversible hydrogen electrode. Schematic illustration (d) of operando differential electrochemical mass spectrometry (DEMS). DEMS signals of O2 products for (e) 18O-surface labeled LaIr-Co3O4, and (f) 18O-surface labeled Ir-Co3O4 in the electrolyte using H216O as solvent.