Facile and green synthesis of a ZnO/CQDs/AgNPs ternary heterostructure photocatalyst: study of the methylene blue dye photodegradation

A photocatalyst based on a ZnO/CQDs/AgNPs ternary heterostructure was synthesized by a green and easy in-situ hydrothermal method. The carbon quantum dots (CQDs) were used in order to reduce AgNO3 to form silver nanoparticles (AgNPs). The as-prepared photocatalyst was characterized by different techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometer, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Bruner-Emmett-Teller. The optical properties of the nanocomposites were examined using UV-visible spectrophotometer. The photocatalytic activity of ZnO/CQDs/AgNPs was evaluated by degradation of methylene blue (MB) under UV light irradiation. The ternary heterostructure exhibits higher photocatalytic activity compared to pure ZnO, ZnO/CQDs and ZnO/Ag. It was found that a degradation of 98.6% of MB was achieved within 50 min of UV light irradiation. Finally, a possible mechanism is proposed to explain the photodegradation of MB by this nanocomposite.

Automated summary

A ternary heterostructure photocatalyst based on ZnO/CQDs/AgNPs was synthesized and exhibited higher photocatalytic activity compared to pure ZnO, ZnO/CQDs, and ZnO/Ag. The photocatalyst was able to achieve a degradation of 98.6% of methylene blue within 50 minutes of UV light irradiation. Additionally, a possible mechanism for the photodegradation of methylene blue by this nanocomposite was proposed.