Fig. 4: In situ XAFS characterization of S-Cu-ISA/SNC.
a Schematic of the in situ electrochemical cell set-up. CE, counter electrode; WE, working electrode; RE, reference electrode. b Cu K-edge XANES spectra of S-Cu-ISA/SNC at various potentials during ORR catalysis in O2-saturated 0.1 M KOH. c Differential Δµ XANES spectra obtained by subtracting the normalized spectrum at every potential to the spectrum recorded at 1.05 V vs. RHE. d Current density as a function of potential for S-Cu-ISA/SNC (left) and the average oxidation number of Cu species in S-Cu-ISA/SNC as a function of potential (right). e k3-weighted FT-EXAFS at ex-situ, 0.90 V and 0.75 V vs. RHE. The shaded region highlighted the variations in the peak position of the first coordination shell. f The proposed ORR mechanism for the S-Cu-ISA/SNC.
