The photocatalytic decolorization of organic dyes is considered one of the most efficient and promising methods. Bismuth Subcarbonate (Bi2O2CO3) exhibits photocatalytic activity, although its wide bandgap limits its ability to absorb visible light. Therefore, it is important to extend the light-responsive range. In this work, Bi2O2CO3 photocatalysts were prepared by adding bromide (Br) sources and subjecting them to nitric acid treatment under various conditions. The photocatalytic activity of the prepared Bi2O2CO3 was evaluated by decolorization experiments using Rhodamine B (RhB) as a representative dye.
To provide pretreatment Bi2O2CO3, Br sources were dissolved in nitric acid solutions of different concentrations. Then, Bi2O2CO3 was added to the resulting solution, and the mixture was stirred for 2 hours. Finally, the products were washed with water and ethanol and vacuum-dried at 60°C for 12 hours.
The photocatalytic activity was assessed by the decolorization of RhB. In particular, 20 mg of the synthesized photocatalyst was dispersed within the RhB solution (10 ppm, 35 mL) and stirred in the dark for 60 min to achieve adsorption/desorption equilibrium. The solution was then irradiated with a 500 W Xe lamp (λ ≥ 420 nm). At regular intervals, the aliquots of the solution were collected and centrifuged. The decolorization rate of RhB was analyzed using a UV–visible spectrophotometer by measuring the absorbance at 554 nm.
Pure Bi2O2CO3, as well as catalysts treated only with acid or only with a Br source, exhibited almost no photocatalytic activity under visible-light irradiation. Acid-treated Bi2O2CO3 with cetrimonium bromide (CTAB) as the Br source enhanced RhB decolorization performance. The results showed that the combined effects of these modifications are essential.
