Visible-Light Degradation of Organic Dye Based on a Heterostructure Photocatalyst
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ORIGINAL PAPER
Visible‑Light Degradation of Organic Dye Based on a Heterostructure Photocatalyst Nguyen Thi Mai Tho1 · Bui The Huy2 · Dang Nguyen Nha Khanh3 · Ngo Thi Tuong Vy3 · Nguyen Quoc Thang1 · Do Trung Sy4 · Le Hoang Hai3 · Nguyen Thi Kim Phuong3,5
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Novel highly visible-light active 1.0rGO–ZnBi2O4–Bi2S3 heterostructure photocatalysts with various weight percentages of Bi2S3 were successfully synthesized. First, the 1.0rGO–ZnBi2O4 catalyst was synthesized by a simple two-step oxidation– reduction and co-precipitation methods, followed by heating at 450 °C. Then, 1.0rGO–ZnBi2O4 was hydrothermally treated with Bi3+, and thiourea in ethylene glycol to obtain the 1.0rGO–ZnBi2O4–Bi2S3 heterostructure photocatalyst. The obtained 1.0rGO–ZnBi2O4–Bi2S3 heterostructure photocatalysts were characterized by X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Photocatalytic studies were conducted using Indigo carmine and it was found that the heterostructure photocatalyst enabled an almost complete degradation of the pollutants. The enhanced catalytic activity of the 1.0rGO–ZnBi2O4–2.0Bi2S3 heterostructure photocatalyst is due to the homogeneous distribution of ZnBi2O4–2.0Bi2S3 over rGO as well as to the efficient electron-transfer from Bi2S3 to ZnBi2O4 and finally to rGO. More than 97% of Indigo carmine of 50 mg/L was degraded by 1.0rGO–ZnBi2O4–2.0Bi2S3 in 75 min of visible light irradiation. The reusability of the 1.0rGO–ZnBi2O4–2.0Bi2S3 was studied, and after four cycles, the Indigo carmine degradation efficiency decreased to 90%.The mechanism of the Indigo carmine degradation by the 1.0rGO–ZnBi2O4–2.0Bi2S3 catalysis likely consists of to two main processes: first, charge transfer prolongs the lifetime of the electron–hole pairs, and then the electron–hole pairs participate in the reactions that produce free radicals. Keywords 1.0rGO–ZnBi2O4–bi2S3 heterostructure photocatalyst · Indigo carmine · Visible-light irradiation · Photodegradation · Kinetic degradation
1 Introduction
* Nguyen Thi Kim Phuong [email protected] 1
Chemical Engineering Faculty, Industrial University of Ho Chi Minh City, Ho Chi Minh City, Vietnam
2
Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Da Nang, Vietnam
3
Hochiminh City Institute of Resources Geography, Vietnam Academy of Science and Technology, 01 Mac Dinh Chi, District 1, Ho Chi Minh City, Vietnam
4
Institute of Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam
5
Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam
Over the past decade, the utilization of solar energy for the degradation of organic pollutants in water has been considered as an ultimate solution for the pollution-related environmental problems. Semiconduc
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