fig5
Figure 5. Proposed S-scheme heterojunction mechanism. (A) Bandgap plots; (B) VB-XPS spectra; (C and D) Work functions; (E) Differential charge density of SMSED/CdS. Cd, Dy, Eu, Si, O, Mg, Sr, and S atoms are denoted by pink, purple, light blue, blue, red, orange, green, and yellow balls, respectively. Electron-deficient zones are denoted by cyan, while electron-rich regions are marked in yellow; (F) Distribution of projected planar charge density difference aligned with the Z-direction; (G) Charge transfer mechanism. Evac: Vacuum level; Ef: fermi level; IEF: internal electric field; Φ: work function; SMSED: Sr2MgSi2O7:(Eu,Dy); VB: valence band; XPS: X-ray photoelectron spectroscopy; CB: conduction band; Eg: bandgap value; WCdS: work function of CdS.
