Synergy photodegradation of basic dyes by ZnO/Bi2O3 nanocomposites under visible light irradiation

Document Type : Research Article

Authors

1 Department of Physics, Mother Teresa Women's University, Kodaikanal.

2 Department of Physics, Mother Teresa Women’s University, Kodaikanal 624 101, Tamil Nadu, India

3 Department of Physics, Mother Teresa Women's University, Kodaikanal.

10.30492/ijcce.2020.105225.3506

Abstract

Environmental problems caused by organic pollutants can be resolved by semiconductor photocatalysts. Using the strategies of doping hydrothermally, Zinc oxide/Bismuth oxide nanocomposites (ZnO/Bi2O3 NCs) comprising of different proportions of BiO for the applications of basic dyes and were tested for antibacterial activity. The average crystallite sizes of these metal oxide nanocomposites were ranging from 12 nm to 29 nm. UV-visible diffuse reflectance spectra were used to determine the optical energy band gap (Eg) of about 2 to 2.82 eV of the NCs for different proportions of the metal oxides. Square-like morphology of ZnO NPs and ZnO/Bi2O3 NCs were observed in the Scanning Electron Microscopy (SEM). This morphological structure along with its high surface area attributes to the promotion of degrading organic pollutants in dyeing wastewater along with decolorization. The photoluminescence (PL) emission intensity of ZnO/Bi2O3 NCs suggests lower recombination rate of photogenerated charge carriers leading to enhanced photocatalytic activity. Visible light-driven photodegradation of MB, MG and R6G by 0.5M ZnO: 0.5M Bi2O3 resulted in high rate constants of 8.5×10-3/min, 6×10-3/min and 9×10-3/min. The hybrid ZnO/Bi2O3 NC materials showed immense antibacterial activity against gram-positive bacterium S. aureus and the gram-negative bacterium E. coli with an inhibition zone of 6mm and 5mm respectively which was comparable to the standard, chloramphenicol. A desired predominant gram-positive bacterial inhibition unwraps a new way for enhanced antibacterial agents. The heterojunction at the interface between Bi2O3 and ZnO could efficiently reduce the recombination of photoinduced electron-hole pairs and thereby enhancing the photocatalytic and antibacterial activity of ZnO/Bi2O3 heterostructures. This study reveals that ZnO/Bi2O3 NCs as a promising candidate for the photocatalytic and antibacterial treatment of dye effluent.

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