Deposition of plasmonic silver nanoparticles onto semiconducting oxide nanosheets and their photochromic behavior

Abstract

Colloidally dispersed niobate nanosheets prepared by exfoliation of layered hexaniobate was modified by Ag nanoparticles by photodeposition, and the Ag-loaded colloidal niobate nanosheets showed photochromic response upon alternating irradiation of UV and visible light. Ag nanoparticles were successfully deposited onto the photocatalytically active niobate nanosheets in colloidal state through UV irradiation in the presence of Ag⁺ ions and ethanol. The deposited Ag nanoparticles exhibit a characteristic absorption band of the localized surface plasmon resonance (LSPR), which was also supported by TEM observations. Visible-light irradiation of the Ag-deposited niobate nanosheets caused reduction of the LSPR band intensity, which was recovered by subsequent UV irradiation. Band position also varied corresponding to the alternate visible and UV light irradiations. The reversible spectroscopic change was ascribed to the oxidative dissolution of the Ag nanoparticles located on the niobate nanosheets with visible-light irradiation and re-deposion of metallic Ag with the UV irradiation, as previously reported for the photochromic system of the composite of Ag nanoparticles and TiO₂.