fig9

Figure 9. (A) Structural models and HAADF-STEM images of Pd₁/CeO₂(100) and Pd_n/CeO₂(111); (B) Fourier transforms of k3-weighted Pd K-edge EXAFS spectra^[83]. Copyright 2023, Wiley; (C) Pt 4f XPS spectra of the Pt-SAs/TMDs samples and commercial Pt/C; (D) The fitted average oxidation states and d-band hole counts of Pt from XANES spectra; (E) First-shell fitting of EXAFS spectra of Pt foil, PtO₂, Pt-SAs/MoS₂, and Pt-SAs/MoSe₂; (F) Relationship of average oxidation state, Pt-OH interaction and alkaline HER activity of PtSAs/TMDs^[84]. Copyright 2023, Springer Nature; (G) Schematic illustration for the preparation of Fe SAs/GO; (H) TEM and (I) HAADF-STEM images of Fe SAs/GO; (J) EXAFS spectra of Fe SAs/GO^[85]. Copyright 2023, Wiley. HAADF-STEM: High-angle annular dark field scanning transmission electron microscopy; EXAFS: extended X-ray absorption fine structure; TMDs: transition metal sulfides; XANES: X-ray absorption near edge structure; SAs: single atoms; HER: hydrogen evolution reaction; GO: graphene oxide; TEM: transmission electron microscopy.