Efficient photocatalytic hydrogen evolution on N-deficient g-C3N4 achieved by a molten salt post-treatment approach

Enhancement of visible‐light photocatalytic degradation performance over nitrogen‐deficient g‐C3N4/KNbO3 heterojunction photocatalyst

“…The C 1s spectrum of pure CN can be resolved into two peaks with binding energy at 288.2 and 284.6 eV, which are attributed to N-C=N coordination and adventitious carbon species (C-C/C=C). 41 Compared to CN, CNx and the 3% KNO/CNx spectra exhibit an intensive peak at 286.1 eV, which could be assigned to C-NHx (x = 1, 2) on the edges of heptazine units, indicating the existence of cyano groups (C≡N) since C≡N groups possess similar C 1s binding energies to C-NHx. 35 In the N 1s spectrum, the N 3c shifts from 401.1 eV to 400 eV which could be ascribed to the existence of cyano groups whose N 1s binding energy are intermediate between those of N 2c and N 3c.…”

“…40 In particular, the FTIR spectrum of the CNx shows an extra vibration band at 2177 cm −1 , which is ascribed to the asymmetric stretching vibration of cyano groups (C≡N), indicating the existence of N-defect in CNx. 41 For pure KNO, there is a board and strong peak at 610 cm −1 , attributing to vibrations of Nb─O bond. 42 The 3% KNO/CNx composite showed a similar wileyonlinelibrary.com/jctb spectrum to CNx, which is attributed to the low concentration of KNO and the strong IR response of CNx.…”

“…Typically, multiple peaks, such as 807 cm −1 , 900–1800 cm −1 and 3000–3500 cm −1 , are assigned to the vibrating mode of the triazine unit, N‐C=N heterorings in the ‘melon’ framework and the stretching vibration of N─H stretching vibration, respectively . In particular, the FTIR spectrum of the CNx shows an extra vibration band at 2177 cm −1 , which is ascribed to the asymmetric stretching vibration of cyano groups (C≡N), indicating the existence of N‐defect in CNx . For pure KNO, there is a board and strong peak at 610 cm −1 , attributing to vibrations of Nb─O bond .…”

“…(e, f), the C 1s and N 1s high‐resolution XPS spectra of CN, CNx and 3% KNO/CNx are compared. The C 1s spectrum of pure CN can be resolved into two peaks with binding energy at 288.2 and 284.6 eV, which are attributed to N‐C=N coordination and adventitious carbon species (C‐C/C=C) . Compared to CN, CNx and the 3% KNO/CNx spectra exhibit an intensive peak at 286.1 eV, which could be assigned to C‐NH x ( x = 1, 2) on the edges of heptazine units, indicating the existence of cyano groups (C≡N) since C≡N groups possess similar C 1s binding energies to C‐NH x .…”

C/N Vacancy Co‐Enhanced Visible‐Light‐Driven Hydrogen Evolution of g‐C3N4 Nanosheets Through Controlled He+ Ion Irradiation

“…In order to further understand the effect of vacancies on the band structure of g‐C 3 N 4 , the valance band (VB) XPS spectra were collected (Figure a). The valance band maximum (VBM) of samples are similar, which are estimated to be 1.56 V versus normal hydrogen electrode (NHE) at pH = 7.0 using the formula E NHE / V = Ф + 1.63 eV‐4.44 eV ( E NHE : normal hydrogen electrode, Ф of 4.37 eV: the electron work function of the analyzer) . The result show that the introduction of C‐ and N‐ vacancies does not influence the VBM of g‐C 3 N 4 .…”