The visible light-driven photocatalytic degradation of Alizarin red S using Bi-doped TiO2 nanoparticles

Abstract

In this paper we report the preparation of a series of Bi³⁺-doped TiO₂ nanoparticles with different Bi-concentrations, i.e. 0.25–5% by a facile sol–gel process and their application as an efficient photocatalyst. The detailed characterization revealed that the Bi-doped TiO₂ catalysts possess densely grown nanoparticles, a high specific surface area, crystalline anatase TiO₂ and good optical properties. The incorporation of Bi³⁺ into the TiO₂ lattice led to the expansion of the TiO₂ spectral response into the visible light region and the efficient separation of charge carriers. The prepared samples were employed for the photocatalytic degradation of Alizarin red S dye (ARS) under visible light illumination. It was found that the incorporation of the Bi³⁺ ions in the TiO₂ lattice causes a marked improvement in the photocatalytic degradation of the ARS dye; however, the degradation efficiency depended upon the Bi⁺³ ion doping concentration and the dose of the prepared catalyst. The detailed photocatalytic experiments confirmed that the 1% Bi⁺³ ion doping concentration and 0.1 g L⁻¹ dose exhibited the best photocatalytic degradation efficiencies for the model dye. Moreover, more than 80% degradation of ARS was observed by the prepared Bi-doped catalysts within 90 minutes under visible light. The synthesized Bi-doped TiO₂ nanoparticles revealed a superior photocatalytic behavior towards the photocatalytic degradation of ARS under similar experimental conditions, as compared to the synthesized TiO₂ nanoparticles and other commercially available derivatives (TiO₂ PC-50 and TiO₂ P25).