Thermally Activated Composite Y2O3-bTiO2 as an Efficient Photocatalyst for Degradation of Azo Dye Reactive Black 5

Water pollution from textile effluents poses serious environmental risks, particularly due to persistent anionic dyes such as Reactive Black 5 (RB5). This study demonstrates that simple deposition of Y₂O₃ onto commercially available, biobased TiO₂ (bTiO₂) significantly enhances photocatalytic degradation efficiency under simulated sunlight, suppressing rapid recombination of electron-hole pairs. Addressing a key research gap, the proposed method replaces expensive nanoscale precursors and complex synthesis routes typically used for Y₂O₃/TiO₂ systems with a low-cost, straightforward approach involving weak complexation and co-precipitation. The resulting Y₂O₃-bTiO₂ composite was characterized using FTIR, XRD, SEM, EDX, TEM, XPS, and UV-DRS techniques, confirming efficient incorporation of Y₂O₃ on the TiO₂ surface. Photocatalytic experiments revealed that nanoparticles calcined at 700 °C achieved complete RB5 degradation within 60 min-reducing the reaction time by half compared to undoped bTiO₂. Systematic studies of initial dye concentration, catalyst loading, and irradiation time confirmed that the degradation followed pseudo-first-order kinetics with a rate constant of 0.064 min^-1 (R² = 0.98). Calculated quantum yields corroborated the reduced electron-hole recombination induced by Y₂O₃ deposition. These findings highlight the novelty and practicality of the developed Y₂O₃-bTiO₂ photocatalyst as an efficient, affordable, and environmentally sustainable material for the degradation of industrial dyes.