Preparation and application of BiOBr-Bi2S3 heterojunctions for efficient photocatalytic removal of Cr(VI).

Recently, the photocatalytic reduction of Cr(VI) has been extensively studied. Herein, we successfully prepared the BiOBr-Bi2S3 heterojunctions with high photocatalytic Cr(VI) reduction performance using an ion exchange method. The optimal BiOBr-Bi2S3 heterojunction (prepared with BiOBr, pH of 6.0, 2 mmol Na2S2O3·5H2O,) achieved 100% removal of Cr(VI) within 12 min. The performance of photo-reduced Cr(VI) was about 28.9 and 184.6 times higher than that of pure Bi2S3 and BiOBr, respectively. Besides, BiOBr-Bi2S3 heterojunctions had a good adsorption efficiency for Cr(III), suggesting that they could be applied as bifunctional photocatalyst. The formation process and photoelectric properties of the BiOBr-Bi2S3 heterojunctions were revealed by a series of characterizations. In conclusion, this work reported the synergistic effect of adsorption and photocatalysis of the BiOBr-Bi2S3 heterojunctions for Cr removal for the first time, suggesting that the BiOBr-Bi2S3 heterojunctions could act as a novel photocatalytic adsorbent to treat the Cr(VI)-containing wastewater.