fig4

Figure 4. Structural evolution and theoretical analysis of the CuC₂O₄-modified interface. (A) XRD patterns, (B) FT-IR spectra, (C) Raman spectra, (D-F) XPS O 1s, C 1s, and Cu 2p spectra of ZP@CuC₂O₄ before and after discharge; (G) DFT-calculated H₂O adsorption energies at C=O and C-O sites; (H) DFT-calculated H₂O adsorption energies at Cu, Cu⁺, and Cu²⁺ sites; (I) DFT-calculated Zn²⁺ adsorption energies at C=O and C-O sites; (J) DFT-calculated Zn²⁺ adsorption energies at Zn, Cu⁺, and Cu²⁺ sites. XRD: X-ray diffraction; FT-IR: Fourier-transform infrared; XPS: X-ray photoelectron spectroscopy; DFT: density functional theory; SD: standard deviation; ΔE: energy spread; PDF: powder diffraction file.