fig4

Figure 4. Structural characterization. (A) Difference patterns for the Rietveld refinement from the XRD of 2D P,N,S-Mo₂C; (B-E) High-resolution XPS spectra of Mo 3d, p 2p, N 1s and S 2p of 2D P,N,S-Mo₂C; (F) Summary of the proportion of each heteroatom in 2D doped-Mo₂C. XRD: X-ray diffraction; 2D: two-dimensional; Mo₂C: molybdenum carbides; XPS: X-ray photoelectron spectroscopy.