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Photocatalytic Reduction of 4-Nitrophenol over Bismuth Sulfur/ Titanium Dioxide Heterojunction: Influence of Bismuth Sulfur Content on the Reaction Efficiency

Abstract:

Photocatalytic reduction of 4-nitrophenol is one of the most promising methods to remove this hazardous pollutant from wastewaters and generated a raw compound widely use in industrial processes. In the present work, three Bi2S3/TiO2 catalysts with different Bi2S3 content, were synthesized by a hydrothermal method. The materials were characterized by X-Ray Diffraction (XRD), X-ray fluorescence, physisorption of N2, High-Resolution Transmission Electron Microscopy (HRTEM), UV-Vis reflectance spectroscopy and zeta potential measurements. The catalytic activity of the synthesized materials was tested in the photoreduction of 4-nitrophenol in aqueous medium. Although the results indicate the formation of heterojunction for all the samples, the physicochemical properties of each material depend on the Bi2S3 content. The material with 6 wt.% Bi2S3 presents an adequate distribution of Bi2S3 on TiO2, suggesting an inhibition of grain growth, resulting in a smaller particle size, likewise the material presented a band gap energy (Eg) of 2.7 eV, improving light absorption compared to TiO2 alone, allowing to generate more charge carriers improving its photocatalytic activity, reducing 80% of the target molecule in 60 minutes of reaction.