Development of Ag/Ag2O/ZnO photocatalyst and their photocatalytic activity towards dibutyl phthalate decomposition in water

Abstract

ABSTRACT The photocatalyst Ag/Ag2O-modified ZnO, fabricated by a simple one-step calcination method, was applied into the degradation of organic pollutant dibutyl phthalate (DBP). Ag/ZnO and Ag2O/ZnO were prepared as a reference comparison. The prepared catalysts were evaluated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), BET surface area measurement, and photoluminescence spectra (PL) and UV–Vis diffuse reflectance spectroscopy (DRS) and electrochemical measurements. After the irradiation with ultraviolet light (352 nm), the solution was sampled and subjected to HPLC to evaluate the degradation efficiency of DBP. Ag/Ag2O/ZnO showed the best results with the excellent degradation of DBP. Ag/Ag2O/ZnO was four times more efficient, relative to zinc oxide alone. According to photocatalyst characterization, the total pore volume of photocatalyst was improved by loading Ag and Ag2O, suggesting an increase in the active sites. Also, the efficient electron transfer of Ag/Ag2O/ZnO was mainly responsible for the enhanced activity. The reaction mechanism for Ag/Ag2O/ZnO was determined to become a Z-scheme. From the radical scavenger tests, the main active species was identified as superoxide radicals. The stability of Ag/Ag2O/ZnO could be confirmed after five cycling reutilization. It was found from the radical scavenger test that •O2 – play an important role as the main reactive species in the photocatalytic degradation of DBP. Consequently, Ag/Ag2O/ZnO with a simple fabrication method seems to become one of the powerful photocatalyst for the photocatalytic degradation of organic pollutant in water. Implications: This study discusses the usefulness of Ag/Ag2O/ZnO composites. This photocatalyst could be an approach to solve the environmental pollution caused by organic pollutants, which is a growing problem all over the world. In addition, the highly efficient photocatalyst Ag/Ag2O/ZnO is an inexpensive and reusable catalyst with great practical potential. Furthermore, to the best of our knowledge, there are very few reports that have examined the combination of Ag, Ag2O and ZnO. In addition, the photocatalytic mechanism has not been understood. Here, we introduce Ag into Ag2O/ZnO to improve the photocatalytic performance and photostability, enhance the activity, and elucidate the mechanism of Ag/Ag2O/ZnO.