Synthesis of ZnO/ZnS/g-C3n4 Nanocomposite for the Sensitive and Selective Electrochemical Detection of Ascorbic Acid

In this study, ZnO/ZnS/g-C 3 N 4 composite materials were successfully synthesized via a combination of hydrothermal treatment and calcination for the electrochemical detection of ascorbic acid (AA). A systematic experimental design was implemented to evaluate the influence of key parameters, including the amount of ZnS added, the loading ratio of ZnO/ZnS onto g-C 3 N 4 , and the pH conditions during detection, on sensor performance. Comprehensive material characterization was conducted using scanning electron microscopy transmission electron microscopy X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, providing detailed insights into the composites’ microstructure, crystallinity, elemental composition, and chemical bonding. The sensor exhibited excellent performance for AA detection, with a broad linear detection range of 20–5000 μM, a low detection limit of 1.2 μmol/L (S/N = 3), and high recovery rates between 98.23% and 105.02%, accompanied by low relative standard deviations (1.56–3.12%). Furthermore, application of the sensor in cyclic voltammetry analysis of commercial vitamin C tablets yielded accurate and reliable results, confirming its strong stability, anti-interference capacity, and reproducibility.