The Photocatalytic Activity of Photoresponsive Silver Nanoparticle/Zinc Oxide Composite Thin Films with Unprecedently Elevated Quantities of Silver

Abstract

The photocatalytic efficacy of metallic silver nanoparticle/zinc oxide (Ag-NPs/ZnO) composite thin films, COMP-Ag_x, with varying silver concentrations (0 mol% ≤ x ≤ 100 mol%), is investigated for the degradation of methyl orange (MO). The films were spin-coated on a silica glass surface at 600 °C utilizing the molecular precursor method (MPM). The XRD spectra of these composite thin films revealed three significant peaks corresponding to the diffraction planes of (0 0 2), (1 0 0), and (1 0 1), indicative of the formation of ZnO crystallites in diverse orientations, in conjunction with an additional signal for cubic Ag crystals. The magnitude of the ZnO peaks diminishes as the mol% of silver increases. The images from the SEM confirm the integration of Ag-NPs into the ZnO matrix. The UV/Vis absorption spectra exhibit a 410 nm surface plasmon resonance (SPR) peak for composite Ag-NP/ZnO thin films. The absorption spectra of ZnO and Ag-NP/ZnO composite thin films demonstrate the band gap of ZnO to be 3.4 eV, while the band gaps of the composite thin films nearly approximate that of ZnO. The decomposition rates of the MO solution indicate that composite thin films function effectively under visible irradiation compared to pure ZnO. The optical properties indicated that the SPR of Ag-NPs contributed to the visible responsiveness of the composite thin films. The SPR demonstrate significant visible light responsiveness and essential characteristics during photoexcited electron transfer from the Ag-NPs to the ZnO conduction band.