fig4

Figure 4. Photoelectrochemical properties and mechanism. (A) PL spectra, (B) Transient photocurrent density, (C) EIS curves, (D) UV-Vis spectra, and (E) M-S plots of the BCN and HCN; (F) Band gap structure of BCN, TCN, and HCN; (G) The mechanism illustration for photoreduction of 4-NP using the type-II HCN homojunction photocatalyst. PL: Photoluminescence; EIS: electrochemical impedance spectroscopy; UV-Vis: ultraviolet-visible; M-S: Mott-Schottky; BCN: bulk phenazine-based C₃N₄; HCN: crystallized carbon nitride homojunction; TCN: triazine-based C₃N₄; 4-NP: 4-nitrophenol.