Rapid Room-Temperature Synthesis of Gold Nanoparticles Using Sargentgloryvine Stem Extract and Their Photocatalytic Activity

Gold nanoparticles (Au NPs) were rapidly synthesized in the Sargentgloryvine stem (Ss) extract without the addition of any chemical agent at room temperature. The synthesis time was less than 10 min (even 1.5 min). The reducing and capping properties of the Ss extract were systematically investigated and then the controllable synthesis of Au NPs was achieved based on UV–Vis spectra. Au NPs were further characterized by transmission electron microscopy, selected area electron diffraction, X-ray diffraction and energy-dispersive X-ray spectroscopy analyses. It could be found Au NPs were quasi-spherical with an average size of 15.6 nm and a face-centered cubic crystalline structure. As-obtained Au NPs was used as photocatalysts for the degradation of nitro compounds (2-, 3-, 4-nitrophenol and 2-nitroresorcinol) and exhibited remarkable photocatalytic activity and stability. The rate constants ( K ) of nitro compounds degradation followed the order: K 4-NP  >  K 2-NP  >  K 3-NP  >  K 2-NR . The difference of the rate constants could be caused by the substituent effect originated from different molecular structures of nitro compounds. The rate constant for the 4-nitrophenol degradation could be linearly adjusted by the molar concentration of Au NPs in the degradation system, which is favorable to the practical wastewater treatment. Graphical Abstract