Fig. 2: XPS and XAS characterizations of electrocatalysts.

a Ru 3p XPS spectra of Ru0.5Ir0.5O2 and C-RuO2. b Ir 4 f XPS spectra of Ru0.5Ir0.5O2 and C-IrO2. c Ru K-edge XANES spectra of Ru0.5Ir0.5O2, C-RuO2 and Ru foil. d Ir L3-edge XANES spectra for Ru0.5Ir0.5O2, C-IrO2 and Ir foil. e Fourier-transformed EXAFS spectra of Ru K-edge spectra for Ru0.5Ir0.5O2, C-RuO2 and Ru foil. f Fourier-transformed EXAFS spectra at Ir L3-edge collected for Ru0.5Ir0.5O2, C-IrO2 and Ir foil. g–i Ru K-edge WT-EXAFS of Ru0.5Ir0.5O2, C-RuO2 and Ru foil. j–l Ir L3-edge WT-EXAFS of Ru0.5Ir0.5O2, C-IrO2 and Ir foil.