Construction of Rod-Shaped ZnO/g-C ₃ N ₄ Thin Film Heterojunction Photocatalysts and Enhancement of Their Degradation Performance for Organic Pollutants

This work focuses on fabricating sea urchin-like ZnO/g-C 3 N 4 heterojunction photocatalytic films on zinc foil surfaces via a one-step hydrothermal synthesis combined with self-assembly and electrochemical deposition. The photocatalytic activity is synergistically enhanced by the UV-light absorption of ZnO and visible-light absorption of g-C 3 N 4 . This synergy results in an expanded UV–Vis spectral response range. The materials’ surface morphology, crystalline phase composition, and optical properties were characterized through a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–Vis) spectrophotometry. The influences of reaction time, temperature, precursor concentration, electrodeposition voltage, and duration on the films’ morphology and structure were systematically evaluated. The unique hierarchical ZnO/g-C 3 N 4 framework was found to provide abundant catalytically active sites, significantly enhancing photocatalytic performance. Synergistic enhancement of visible-light absorption and bandgap narrowing in the composite collectively boosted the material’s photocatalytic activity. The prepared ZnO/g-C 3 N 4 films demonstrated exceptional photocatalytic activity in decomposing methyl orange under visible light irradiation. The ZnO/g-C 3 N 4 composite achieved a removal efficiency of over 81.62% for methyl orange after 60[Formula: see text]min of visible light irradiation, with a degradation rate constant ([Formula: see text][Formula: see text]min[Formula: see text]) that is 1.3-fold higher than that of pure ZnO ([Formula: see text][Formula: see text]min[Formula: see text]), corresponding to a [Formula: see text]% enhancement in degradation rate. Compared to other catalysts, ZnO/g-C 3 N 4 demonstrated superior performance in terms of stability, recyclability, and no detectable byproducts. It is anticipated to emerge as a promising candidate for advanced photocatalytic materials with broad applications.