Fig. 4: Operando Ru K-edge XANES and EXAFS spectra of VO-Ru/HfO2-OP. | Nature Communications

Fig. 4: Operando Ru K-edge XANES and EXAFS spectra of VO-Ru/HfO2-OP.

From: The synergistic effect of Hf-O-Ru bonds and oxygen vacancies in Ru/HfO2 for enhanced hydrogen evolution

Fig. 4

a Three-dimensional plot of operando Ru K-edge XANES spectrum recorded at varied potential from OCV to −0.6 V (vs. RHE) during the HER catalysis. b The reversible change of Ru valence state during the electrocatalytic HER process: 1 refers to electrode – OCV: oxidation; 2 refers to OCV – 0 V: reduction; 3 refers to 0 V – −0.1 V – −0.25 V: oxidation; 4 refers to −0.25 V – −0.4 V – −0.5 V: reduction; 5 refers to −0.5 V – −0.6 V: oxidation; 6 refers to −0.6 V – OCV back: reduction. c Three-dimensional plot and d Curves of normalized differentiated XANES intensity (Inth – I1st) in operando Ru K-edge XANES spectra. e Three-dimensional plot of operando Ru K-edge FT-EXAFS spectrum of VO-Ru/HfO2-OP. Changes in the distances and intensities of f Ru-Ru and g Ru-O-Hf in the operando Ru K-edge FT-EXAFS spectrum of VO-Ru/HfO2-OP.

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