fig3

Figure 3. High-resolution XPS spectra of NiCrS/CN (A) Cr 2p spectrum; (B) Ni 2p spectrum; (C) S 2p spectrum; (D) C 1s spectrum; (E) N 1s spectrum. XPS: X-ray photoelectron spectroscopy; NiCrS/CN: nickel-chromium sulfide with nitrogen-doped carbon shell.