Fig. 2: Qualitative and quantitative characterizations.

a, b, c Optimized CN (a), CN-I (b), and CN-I/I3 (c) geometric structures with an isosurface value of 0.009 e/Bohr3. d TEM-EDS mappings of CN-I/I3. e–k XPS spectra (e, f, g), FT-IR spectra (h), XRD patterns (i), C K-edge (j), and N K-edge (k) XANES spectra of CN, CN-I, and CN-I/I3. l ESR spectra of CN and CN-I/I3. m, n, o TEM (inset), and HR-TEM images of CN (m), CN-I (n), and CN-I/I3 (o). p Relationship between H2O2 production and FWHM value of the (002) plane for samples with different CN-I-I2 ratios.