Synthesis of plasmonic Ag-ZnO-TiO2 nanocomposites for enhanced visible-light photocatalytic activity

Abstract

Recent studies have investigated semiconductor photocatalysts such as Zinc Oxide (ZnO) and Titanium Dioxide (TiO₂) for solar-driven environmental remediation, particularly in wastewater and treatment. The nanocomposites were prepared by incorporating silver into ZnO and subsequently combining the Ag-ZnO component with TiO₂. In this study, a novel Ag-ZnO-TiO₂ nanocomposite photocatalyst was successfully synthesized via the sol-gel method using different TiO₂ ratios (1:1, 1:2, and 2:1). The composites were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and UV-Vis spectroscopy. XRD analysis confirmed orthorhombic and hexagonal crystal structures, while SEM revealed aggregated particles with predominantly spherical morphology. The optical band gaps of the Ag-TiO₂-ZnO composites were found to be 3.16, 2.61, and 2.95 eV. Photocatalytic performance under visible light irradiation against synthetic dyes showed significant enhancement compared to bare ZnO and TiO₂. The photocatalytic performance of the nanocomposites was evaluated using methylene blue as a model organic pollutant under light irradiation. This improvement was attributed to enhanced electron transfer, reduced electron-hole recombination and increased visible-light absorption induced by plasmonic Ag nanoparticles.