Melamine-Induced Carbon-Doped Anatase TiO₂ for Enhanced Visible-Light-Driven Photocatalytic Degradation: Synthesization, Performance, and Mechanism

The preparation of high-performance photocatalysts is essential for the effective degradation of organic pollutants. In this study, a melamine-modified titanium dioxide (TiO2) photocatalyst was synthesized via a straightforward hydrothermal and calcination method, using tetrabutyl titanate as the titanium precursor and melamine as the carbon source. This study explores the synthesis of melamine-modified anatase TiO2 and its application in the photocatalytic degradation of tetracycline (TC) across various water sources. After 180 min of continuous light exposure, the melamine-modified TiO2 (CT3) exhibited the optimum photocatalytic performance, achieving a degradation rate of 91.29% in seawater and approximately 90% in Xiangjiang River water and groundwater. Additionally, CT3 demonstrated a significant increase in hydrogen production, reaching 15,649 μmol/g, a substantial enhancement compared to unmodified TiO2. The photocatalytic reaction mechanism was investigated through radical trapping experiments, and the analysis of TC degradation intermediates. Toxicity analysis of the intermediates emphasized their potential environmental impacts. Combined with characterization and experimental findings, the results demonstrate that melamine modification enhances electron capture and transport, facilitating charge transfer and separation of photogenerated carriers, thereby significantly boosting photocatalytic activity. This research highlights the potential of melamine-modified TiO2 in effectively addressing environmental contamination and advancing sustainable energy solutions.