Sol-gel synthesis of black ZnO/AuNPs nanocomposites for effective photocatalytic activity of methylene blue

Abstract

In this study, we present a facile method for the fabrication of ZnO/AuNPs hexagonal wurtzite structure by sol-gel method. Transmission electron microscope (TEM) results indicate that the synthesized AuNPs have good round shape and uniform size with an average diameter of 15 nm. Scanning electron microscope (SEM) results show that the prepared ZnO/AuNPs nanocomposites are uniform spheroidal nanoparticles with sizes in diameter from 60 nm to 100 nm. The presence of Zn, Au and O elements in those samples is determined by X-ray photoelectron spectroscopy (XPS) analysis. The investigation of photocatalytic ability shows that the ZnO/AuNPs (8 mL) achieve complete degradation of methylene blue (MB) under UV irradiation with 65 min. We can conclude that the presence of AuNPs hybrid ZnO can strongly enhance the photocatalytic performance of MB compared to pure ZnO, which may be attributed to the larger specific surface area and surface plasmon resonance (SPR) effect of AuNPs hybrid ZnO nanocomposites. This method may provide a new way to improve ZnO photocatalysis for water cleaning application.