Fig. 3: Dynamics of Ir and O oxidation probed by time-resolved operando optical and X-ray spectroscopies.
a, Time-resolved optical absorption changes during potential step experiments on IrOx in 0.1-M HClO4 electrolyte. Potentials (non-iR-corrected) were stepped from 0.6 to 0.8 VRHE, 1.1 to 1.3 VRHE and 1.41 to 1.5 VRHE. Optical absorption was monitored at wavelengths of 600 nm, 800 nm and 500 nm, corresponding to the maximum absorption wavelength for redox transitions 1, 2 and 3, respectively (Supplementary Fig. 7). b, Changes in fluorescence intensity at the Ir L3 edge (11,222 eV) during potential step experiments on IrOx deposited on an FTO substrate in 0.1-M HClO4 electrolyte. Potential steps were applied between 0.6 and 0.8 VRHE, 1.12 and 1.3 VRHE and 1.44 and 1.5 VRHE, corresponding to redox transitions 1, 2 and 3, respectively, as identified from the spectral deconvolution in optical spectroscopy. c, Changes in the fluorescence intensity at the O K edge during potential step experiments in 0.1-M HClO4 electrolyte. Potentials (non-iR-corrected) were stepped in the ranges of 0.62–0.82 VRHE, 1.1–1.27 VRHE and 1.32–1.52 VRHE. Fluorescence intensity changes were monitored at 529 eV for the potential ranges of 0.62–0.82 VRHE and 1.1–1.27 VRHE, and at 528.7 eV for the range of 1.32–1.52 VRHE.
