Synergistic effect of hybrid Ce³⁺/Ce⁴⁺ doped Bi₂O₃ nano-sphere photocatalyst for enhanced photocatalytic degradation of alizarin red S dye and its NUV excited photoluminescence studies

Highly spherical structured Ce³⁺/Ce⁴⁺ doped Bi₂O₃ nanosphere photocatalyst was prepared by simple solid state reaction route. The crystallite phase of a photocatalyst plays an important role on its activity. Hence, the phase of the catalyst is suitably tuned by varying cerium concentration and calcination temperature. From the experimental data it is evident that, 9 wt% cerium doped Bi₂O₃ calcinated at 600 °C showed better photocatalytic performance for the degradation of Alizarin red S dye. The enhanced performance of this optimized catalyst is due to synergistic effect by the presence of inter convertible Ce³⁺/Ce⁴⁺ oxidation states and mixed α-β phase Bi₂O₃. Addition of EDTA-2Na and radical scavengers (Benzoquinone, t-BuOH) decreased the photocatalytic efficiency, which indicates that, the presence of O₂, O₂^- and OH radicals and their significant role in the degradation of ARS dye. A plausible mechanism and degradation pathway of ARS degradation has been proposed.