Visible-light-induced enhanced photocatalytic degradation of Rhodamine-B dye using Bi_xSb_2-xS₃ solid-solution...

The present work examines binary solid solutions of Bi_xSb_2-xS₃ [x = 0.536, 1.09, 1.68] toward photocatalytic degradation of Rhodamine-B (RhB) under visible light. Phase and microstructural analysis confirmed the formation of Bi_0.536Sb_1.464S₃, Bi_1.09Sb_0.91S₃, and Bi_1.68Sb_0.32S₃ solid-solution phase with nanorods (~25-50 nm average diameter) morphology. The synthesized products show outstanding photocatalytic degradation of RhB with ~95-99.5% degradation achieved within 30 min. The kinetic study finds the high degradation efficiency (~98%) of Bi_xSb_2-xS₃ photocatalysts stems from the amenable band gap (~2.3 eV, confirmed from DRS study), and higher separation efficiency of photogenerated electron-hole pairs (established from PL studies). The complete detoxification of RhB dye was confirmed by quantitative estimation of CO₂ post photodegradation through GC analysis. Moreover, due to the solid and hard nature of the photocatalysts, it was easily recovered from the reaction mixture and reused multiple times without losing the degradation behavior. The parallel comparison with other active photocatalysts demonstrates Bi_xSb_2-xS₃ [x = 0.536, 1.09, 1.68] have higher catalytic efficiency with similar dosing hitherto reported in the literature and possibly can be used for degradation of other organic dyes using the visible spectrum.