Nonmetal-Doped High-Crystalline g-C₃N₄ Nanostructures for Visible-Light-Driven Pollutant Degradation and Biomedical...

Graphitic carbon nitride (g-C₃N₄), a metal-free polymeric semiconductor, has attracted increasing attention for photocatalytic and biomedical applications due to its visible-light responsiveness, tunable electronic structure, and chemical robustness. However, its practical utility remains constrained by poor crystallinity, limited active surface sites, and rapid electron-hole recombination. In this study, a facile one-step calcination strategy was employed to synthesize highly crystalline, non-metal-doped g-C₃N₄ nanostructures with enhanced physicochemical properties. Structural and optical characterizations revealed improved crystallinity, expanded surface area, defect-rich architecture, and extended visible-light absorption. These features significantly boosted the photocatalytic performance for the degradation of Reactive Blue 222, achieving up to 89% removal within 90 min under visible light, with the degradation kinetics following a pseudo-first-order model (k = 0.97 min⁻¹). Beyond environmental remediation, the modified g-C₃N₄ also demonstrated notable anticancer activity against HCT-15 (colon cancer) cell lines. Cytotoxicity assays revealed concentration-dependent inhibition, with IC₅₀ values of 7.10 µg/mL, respectively, indicating its potential as a photodynamically active nanomaterial for cancer therapy. The dual functionality of visible-light-driven photocatalysis and selective anticancer activity underscores the potential of engineered g-C₃N₄ as a sustainable platform for integrated environmental and biomedical applications.