Solvothermal synthesis of Ag/ZnO and Pt/ZnO nanocomposites and comparison of their photocatalytic behaviors on dyes degradation

Abstract

Noble metal/ZnO nanoparticles were synthesized by a solvothermal method. The influence of reaction time, noble metal presence or kind of noble metal (Ag or Pt) was evaluated. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS) and BET surface area analysis. Hexagonal wurtzite and fcc were obtained for crystalline structures for ZnO and Ag/Pt, respectively. No characteristic phases which correspond to crystalline impurities were detected. It was displayed that ZnO nanoparticles presented nanowire morphology (NWs), while the metallic silver or platinum were found taking on quasi-spherical nanoparticles morphology (NPs), which appeared well dispersed onto ZnO NWs surface. Regarding particle sizes, ZnO aspect ratios were 2.5–13.3, Ag and Pt diameters were 17.3–24.3 nm and around ≈6.3 nm, respectively. The photocatalytic behavior of the synthesized systems was studied as well by the removing reaction of methylene blue (MB) in water solution. It was verified that the increase of the photocatalytic activity was due to the noble metal presence, exhibiting higher effect of silver than platinum. Photocatalytic results (all samples reached >70% MB elimination) demonstrated the viability of the noble metal/ZnO nanocomposites synthesized by solvothermal method for usage in environmental applications.