Facile and Eco-friendly Synthesis of Bi₂O₃ Nanoparticles: Effect of Templating Agents on Morphology and Photocatalytic performance

A novel soft-chemical synthesis method was used to synthesis nanostructured α-Bi₂O₃. The method uses chitosan (Cs) and sodium alginate (Alg) as directing agents, representing an environmentally friendly approach that has not been explored previously for this oxide. The impact of these biopolymers on the formation of α-Bi₂O₃ is thoroughly examined using the precipitation method. The resulting α-Bi₂O₃ catalysts are characterized using FTIR, XRD, UV/Vis, EDX, SEM, and BET techniques, and they are subsequently utilized for the photocatalytic degradation of Acid Orange 7 (AO7). It is found that both α-Bi₂O₃-Cs and α-Bi₂O₃-Alg photocatalysts demonstrate remarkable stability and high photocatalytic activity in degrading AO7 under both ultraviolet-B and visible light. Notably, 90% dye removal at a pH of 6.31 is achieved by α-Bi₂O₃-Cs without the need for further pH adjustment, contrasting with the 55% achieved by α-Bi₂O₃-Alg. The pollutant's decomposition was confirmed through LC–MS analysis. Furthermore, the influence of the templating agent on the morphology of the photocatalyst and its efficiency in photodegradation is observed. Optimization studies utilizing Central Composite Design (CCD) and degradation kinetics were reported. Additionally, the adsorption mechanism of AO7 on α-Bi₂O₃ catalyst is investigated using Density Functional Theory (DFT), and Fukui functions are employed to predict photocatalytic degradation. The consistency between DFT findings and experimental results enhances the comprehension of the mechanisms involved in AO7 dye degradation using α-Bi₂O₃ catalysts.