A stable and regenerative TiO₂/Bi₂MoO₆ photocatalyst for highly effective degradation of Rhodamine B and Congo Red

ABSTRACT

This research unravels a facile method for synthesising TiO₂/Bi₂MoO₆ photocatalysts and their effective applications in degrading industrial dyes. Initially, Bi₂MoO₆ was prepared as the substrate, followed by the addition of TiO₂ to form the TiO₂/Bi₂MoO₆ composite. The photocatalyst was characterised by powder X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM-EDS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Its photocatalytic properties were evaluated by dye degradation under various conditions, including different dopant loading amounts, the reaction time, the initial concentration of the dye, and pH values. The results indicated that 50 mg of 15% TiO₂/Bi₂MoO₆ achieved the highest photodegradation efficiency: 98.51% for 50 mL 10 mg L⁻¹ Rhodamine B (RhB) within 100 min in a neutral buffer solution and 90.71% for 50 mL 10 mg L⁻¹ Congo Red (CR) within 80 min in an aqueous solution. This material exerted effectiveness across a wide pH range, with removal rates of RhB exceeding 95.41% in both acidic and alkaline conditions. The degradation process conformed to the pseudo-first-order kinetic model. Radical trapping experiments revealed that the dye degradation mechanism involved $\bullet {\mathrm{O}}_2^{-}$ and h⁺. Notably, the synthesised TiO₂/Bi₂MoO₆ photocatalyst demonstrated high stability and reusability, maintaining performance even after four degradation cycles. The TiO₂/Bi₂MoO₆ photocatalyst, with TiO₂ as the dopant and Bi₂MoO₆ as the substrate, demonstrated significant versatility and potential for practical dye degradation applications.

KEYWORDS:

• Photocatalysis
• TiO₂
• Bi₂MoO₆
• dye degradation

Acknowledgments

The authors express sincere gratitude to Universiti Malaya and Taiyuan Institute of Technology for their invaluable support, which provided a conducive environment for the execution of this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data supporting this study are included in the article.