Bi2S3-sensitized TiO2 nanostructures prepared by solution process for highly efficient photoreduction of hexavalent chromium ions in water under visible light

• Published in: Optical materials 2022-02, Vol.124, p.111964, Article 111964
• Main Authors: Shawky, Ahmed, Alahmadi, Nadiyah, Mohamed, R.M., Zaki, Z.I.
• Format: Article
• Language: English
• Subjects: Heavy metal ions; Heterojunctions; Mesostructured TiO2; Metal chalcogenides; Photocatalytic reduction
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2021.111964

The release of hexavalent chromium ions (Cr (VI)) in water can pose critical intimidations to the ecological environments and highly hazardous impacts on health. This study demonstrates the construction of nanostructured Bi2S3/TiO2 as a visible-light active photocatalyst for the rapid reduction of Cr(VI) to trivalent chromium ions (Cr(III)). Mesostructured TiO2 was grown by surfactant-assisted sol-gel process. The Bi2S3 of 8.3 nm in size were anchored the 19.4 nm TiO2 rhombohedra by coprecipitation at 1.0–4.0 wt%, as proved by TEM, XPS, and XRD explorations. The absorption of visible light was enhanced as a result of bandgap reduction to ∼2.5 eV for the 3.0% Bi2S3/TiO2. This developed Bi2S3-sensitized TiO2 achieved a fast photocatalytic reduction of Cr(VI) at 284.2 μmol min−1 within just 30 min by adjusting dose at 2.0 gL−1. In addition, this developed photocatalyst showed magnificent reproducibility for five runs. This promoted photoactivity is ascribed to the efficient interfacial charge separation by Bi2S3 sensitization as inveterate by photoluminescence and photocurrent measurements. This work opens the door for plenty of metal chalcogenide-based oxide nanostructured photocatalysts for heavy metal remediation under visible light. [Display omitted] •Bi2S3 nanoparticles sensitized sol-gel prepared mesoporous TiO2 at 1.0–4.0 wt%.•Eg down to 2.5 eV, visible-light response, and suppression of charge recombination.•Photoreduction of Cr(VI) promoted by > 57 times at 3.0% loading of Bi2S3.•Recyclable Cr(VI) photoreduction in 30 min for 5 cycles at 284.2 μmol min−1.