fig4

Figure 4. Producing scheme and characterization of thermally oxidized porSi wafers (SiO_x-porSi)^[126]. (A) Scheme for synthesizing SiO_x-porSi using electrochemical etching and thermal oxidation; (B) FTIR spectrum of conversion of H-porSi to SiO_x-porSi according to heating time; (C) XPS spectra of intact and powdered SiO_x-porSi samples in the Si 2p region; (D) Cross-sectional SEM image and EDS mapping for Si and O of SiO_x-porSi. Reprinted with permission from Ref.^[126]. Copyright © 2025, Elsevier. FTIR: Fourier transform infrared; XPS: X-ray photoelectron spectroscopy; SEM: scanning electron microscopy; EDS: energy-dispersive X-ray spectroscopy.