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

[Display omitted] •A simple solid state reaction method for the preparation of Bi2O3: Ce3+/Ce4+nanospheres has been discussed.•Presence of Ce3+/Ce4+ dual oxidation state was clearly confirmed by XPS analysis.•Enhanced photocatalytic activity due to dual oxidation state of cerium and mixed α-β phase of Bi2O3 has been discussed.•Free radical degradation mechanism was confirmed experimentally by radical scavenger experiments and mass spectral analysis. 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.