Fabrication of BaO-CeO2/TiO2 ternary nanocomposite: an efficient photocatalyst for removal of indigo carmine and rhodamine B

Abstract

The current study investigates the photocatalytic degradation of organic dyes such as indigo carmine (IC) and Rhodamine B (RhB) using BaO-supported CeO₂/TiO₂ as a photocatalyst. The produced nanocomposite was validated using XRD, XPS, UV-Visible, and SEM/EDAX techniques. The higher photocatalytic activity of BaO-CeO₂/TiO₂ compared to CeO₂/TiO₂ could be attributed to an increase in pore diameter, surface area, and oxygen vacancies, as determined by photoluminescence and BET studies. The energy band gap of the BCT composite, calculated using UV-Visible spectroscopy, decreased from 3.32 eV (for pure TiO₂) to 2.43 eV with BaO-CeO₂ incorporation, indicating enhanced visible light absorption. Additionally, the surface area increased from 81.40 m²/g for TiO₂ to 86.24 m²/g for CT and further to 92.98 m²/g for BCT, as determined by BET analysis. The percentage degradation is highest for IC (95.76 %) and RhB (95.70 %) dyes. After four cycles, IC and RhB dyes degraded by around 94.9 % and 93.9 %, respectively, which is comparable to the % degradation of the first cycle of around 96 %. pH analysis reveals that IC and RhB dyes degrade more effectively in alkaline (pH=9) and neutral (pH=7) conditions than in acidic environments. The BaO-CeO₂/TiO₂ nanocomposite remains stable after four cycles of degradation. Kinetic investigations show that both BaO-CeO₂/TiO₂ and CeO₂/TiO₂ can fit with first-order (f.o) models (R²=1). BaO-CeO₂/TiO₂ nanocomposite has a higher degradation rate constant $(K_{f.o}=34.38\times {10}^{-3}$and $K_{f.o}=26.24\times {10}^{-3})$ is higher than that of CeO₂/TiO₂ $(K_{f.o}=18.23\times {10}^{-3}$and $K_{f.o}=18.31\times {10}^{-3})$. Thus, the above findings will assist technicians in designing and synthesising more effective photocatalytic degradation catalysts.