Fig. 7

Characterisation and photocatalytic activity of the annealed Bi_xSn_1−x nano-alloys. a XRD patterns of the eutectic sample after annealing at 500 °C for 1 h. The inset shows the colour of the eutectic sample before and after annealing. b Raman spectra of the Bi–Sn nano-alloys annealed at 500 °C for 1 h. The magnified regions show the relative intensity of the SnO₂ defect mode I_D and active mode I_A. c Plots of ln (c₀/c_t) vs. t for the eutectic samples annealed at different temperatures. d Plots of ln (c₀/c_t) vs. t for the Bi–Sn nano-alloy samples annealed at different 500 °C for 1 h. e The dependence of SnO₂ defect intensity (characterised by I_D/I_A) and dye degradation rate constant k on the mixing ratio of the Bi–Sn nano-alloy samples