Novel near room-temperature and/or light driven Fe-doped Sr2Bi2O5 photo/thermocatalyst for methylene blue degradation

• Fe-doped Sr2Bi2O5 can be excited by near room-temperature and/or Xe light.
• The thermocatalytic and photo/thermocatalytic activities were investigated.
• It showed well thermocatalytic and photo/thermocatalytic activities for removing MB.
• The degradation mechanism was established in detail.

A novel photo/thermocatalyst was synthesized using co-precipitation. The catalyst above was used to degrade the dye methylene blue (MB), via the processes of thermocatalytic degradation (TCD) and photo/thermocatalytic degradation (PTCD). The catalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV–Vis diffusion reflectance spectroscopy (DRS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the Brunauer–Emmett–Teller (BET) technique, and the terephthalic acid photo-luminescence probing technique (TA-PL). Fe-doped Sr2Bi2O5 powder was found to exhibit a high thermocatalytic activity and a high photo/thermocatalytic activity for the degradation of MB. The TCD and PTCD MB removal efficiencies reached 92.6 and 98.8%, respectively. Furthermore, HO and O2− were not found to be the predominant active radicals. Holes were found to be generated in both two TCD and PTCD; however, TA-PL and radical scavenger experiments indicated that more holes were formed in PTCD. This study discussed the probable thermocatalytic and photo/thermocatalytic mechanisms, finding them to be in good agreement with results.

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