fig3

Figure 3. (A) Illustration on the synthesized process of AO-C₃N₄^[101], Copyright 2023, Elsevier Ltd; (B) Schematic diagram of preparing g-C₃N₄-CN^[29], Copyright 2024, Wiley-VCH; (C) The transformation of U 4f XPS spectra on charged K-CN-PHI at different dark exposure times^[104], Copyright 2023, Wiley-VCH; (D) The structure and electrostatic potential of the CCN and Cu-CCN^[105], Copyright 2023, Elsevier Ltd; (E) HRTEM and (F) AFM images of 2D/2D C₃N₅/GO nanosheets^[108], Copyright 2021, Elsevier Ltd. XPS: X-ray photoelectron spectroscopy; K-CN-PHI: K⁺ and cyano group co-decorated poly(heptazine imide); CCN: crystalline carbon nitride; HRTEM: high-resolution transmission electron microscopy; AFM: atomic force microscopy.