fig2

Figure 2. (A) The La 3d XPS spectrum of La-doped MnO₂; The XPS spectra comparison of Mn 2p (B), Mn 3s (C) for La-doped MnO₂ (blue) and pure MnO₂ (pink); (D) The XANES of Mn K-edge for La-doped MnO₂, MnO₂ and Mn foil reference; (E) FT spectra of k³-weighted EXAFS spectra of Mn K-edge in La-doped MnO₂, MnO₂ and Mn foil reference; (F) The WT of La-doped MnO₂ and MnO₂; (G) The O 1s XPS spectra of La-doped MnO₂ (blue) and pure MnO₂ (pink); (H) Mn 2p and (I) Mn 3s (I) spectra of La-doped MnO₂ before and after OER. XPS: X-ray photoelectron spectroscopy; XANES: X-ray absorption near-edge structure spectra; EXAFS: extended X-ray absorption fine structure spectroscopy; WT: wavelet transform; OER: oxygen evolution reaction.