采用原位沉淀法将高温煅烧制得的TiO₂/g-C₃N₄复合物负载到Ag₃PO₄上，制备出三元异质结TiO₂/g-C₃N₄/Ag₃PO₄复合光催化剂，并用于降解罗丹明B（RhB）。通过X射线衍射（XRD）、扫描电镜（SEM）、紫外-可见漫反射光谱（UV-vis DRS）等测试方法对该异质结的组成、微观结构和理化性质等进行表征与分析。研究结果表明，在TiO₂/g-C₃N₄/Ag₃PO₄复合光催化剂中，粒径约为100 nm的TiO₂纳米颗粒均匀地负载于g-C₃N₄和Ag₃PO₄表面，材料的吸收带边发生红移。以RhB为模拟污染物，在可见光照射下TiO₂/g-C₃N₄/Ag₃PO₄异质结表现出优异的光催化活性。可见光照射7 min后，TiO₂/g-C₃N₄/Ag₃PO₄复合光催化剂对RhB的降解率可达99%，明显优于纯g-C₃N₄、TiO₂、Ag₃PO₄及二元复合物，并且在重复使用5次后其光催化降解率仍保持在92%以上，表明TiO₂/g-C₃N₄/Ag₃PO₄异质结具有较强的光催化活性和稳定性。通过捕获实验探究其光催化机理，三元异质结中具有π共轭结构的g-C₃N₄有助于电荷转移，在可见光照射下，异质结中的光生电子积累在g-C₃N₄导带，光生空穴积累在Ag₃PO₄和TiO₂价带，从而促使e^--h⁺对分离，提高了光生载流子的分离效率，此复合光催化剂的主要反应活性物种为光生空穴（h⁺）和超氧自由基（·O₂^-），而电子（e^-）的作用相对较小。

Ternary heterojunction TiO₂/g-C₃N₄/Ag₃PO₄ photocatalyst，loading the calcinated TiO₂/g-C₃N₄ composite on the surface of Ag₃PO₄，was successfully prepared by in⁃situ precipitation for the degradation of Rhodamine B（RhB） dye.The composition，microstructure and physicochemical properties of the samples were characterized by X-ray diffraction（XRD），scanning electron microscopy（SEM），ultraviolet visible diffuse reflectance spectroscopy（UV-vis DRS）.The results showed that TiO₂ nanoparticles with the particle size of about 100 nm were uniformly supported on the surface of g-C₃N₄ and Ag₃PO₄ in TiO₂/g-C₃N₄/Ag₃PO₄ photocatalyst，and the absorption edge of the heterojunction underwent a red shift.Excellent photocatalytic activity of TiO₂/g-C₃N₄/Ag₃PO₄ under visible light irradiation was demonstrated by degrading RhB dye.After exposure to visible light for 7 min，the degradation rate of RhB by TiO₂/g-C₃N₄/Ag₃PO₄ photocatalyst could reach 99%，which was obviously higher than that of pure g-C₃N₄，TiO₂，Ag₃PO₄ and binary complex，and its photocatalytic degradation rate remained above 92% after repeated use for 5 times，indicating its strong photocatalytic activity and excellent stability.Moreover，the photocatalytic degradation mechanism was explored through the capture experiments.In this ternary heterojunction，g-C₃N₄ with π-conjugate structure facilitated charge transfer.Under the irradiation of visible light，the photogenerated electrons accumulated in the conduction band of g-C₃N₄，and the photogenerated holes accumulated in the valence band of Ag₃PO₄ and TiO₂，thus e^--h⁺ pairs were separated effectively to improve the separation efficiency of photogenerated carriers.The primary active species of photocatalyst were photogenerated holes（h⁺） and superoxide free radicals（·O₂^-），while e^- basically had no effect.