Synthesis and characterization of Indium Vanadate (InVO4) loaded on Silver Phosphate (Ag3PO4) for photoreduction of Rhodamine B (RhB) using impregnation method

This research investigates the synthesis and characterization of an Indium Vanadate (InVO4) loaded on Silver Phosphate (Ag3PO4) composite photocatalyst for the efficient degradation of Rhodamine B (RhB) under visible light. The study addresses the environmental risks of RhB, a persistent, toxic, and potentially carcinogenic dye, while overcoming the limitations of pristine Ag3PO4 and InVO4, such as rapid charge carrier recombination and photocorrosion. Using the impregnation method, InVO4/Ag3PO4 (InAP) composites were successfully synthesized with various weight loadings. Physicochemical characterization via X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM) confirmed high crystallinity and the uniform dispersion of InVO4 on the Ag3PO4 surface. Notably, FTIR analysis revealed a slight shift of the In–O vibration band from 406 cm⁻¹ to 413 cm⁻¹ in the composite samples, indicating strong interfacial interactions between InVO₄ and Ag3PO4. (UV-Vis/DRS) further indicated that the optimal composite possessed the narrowest bandgap for enhanced light absorption. Photocatalytic performance tests revealed that a 5 wt.% InVO4 loading (5 InAP) was the most effective ratio, achieving a maximum degradation efficiency of 96% for 10 mg/L of RhB within the experimental duration. The efficiency followed a volcano-shaped trend, declining at higher loadings due to a "shielding effect," and decreased as the initial dye concentration increased due to active site saturation. Mechanistic studies using scavengers confirmed that the degradation process is primarily driven by photogenerated electron (e-) and hydroxyl radicals (•OH) within a well-designed type-II heterojunction system. These findings demonstrate that the InVO4/Ag3PO4 composite is a stable and high-performance photocatalyst suitable for treating dye-contaminated industrial wastewater.