Figure 5: The XPS spectra of N-S-G/Fe₃O₄ composite.

(a) Survey spectrum; (b) XPS high-resolution spectra of the Fe2p region; (c) XPS high-resolution spectra of the C1s region; (d) XPS high-resolution spectra of the O1s region; (e) XPS high-resolution spectra of the N1s region; (f) XPS high-resolution spectra of the S2p region.