(A) Comparison of C_ss calculated from EIS data and (B) open-circuit potential decay curves of BCN, DCN, and other defective g-C₃N₄ samples. (C) CP-MAS ¹⁵N NMR spectra of DCN and NYF-35@DCN. Differential charge density between (D) NYF@DCN and (E) NYF@BCN (olive and cyan iso-surfaces represent the region of net electron accumulation and deficit; grey: C; brown: N; green: S; yellow: Na; dark grey: Y; red: F; blue: Yb; purple: Tm). (F) Proposed photocatalytic mechanism of NYF@DCN photocatalysts.