Preparation And Properties Of Yttrium Oxide Composite Nanotubes Modified By Different Precious Metals

Y（OH）₃:Eu³⁺ nanotubes were synthesized by a facile hydrothermal method first, and then Au particles were grown on the surface of Y₂O₃:Eu³⁺ nanotubes by combining the vacuum extraction method and the annealing process. The composite nanotubes were characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM）, and X-ray photoelectron spectroscopy（XPS）. The effects of the Au content on the photoluminescence properties of the Au/Y₂O₃:Eu³⁺ composite nanotubes were investigated in detail. In the excitation spectra of Au/Y₂O₃:Eu³⁺ monitored at 614 nm, the 7F0→5H3 transition from Eu³⁺ increased with increasing Au content, while the other sharp lines originating from Eu³⁺ f–f electron transitions almost vanished. In the emission spectra, the spectral configurations of Eu³⁺ in Au/Y₂O₃:Eu³⁺ composite nanotubes varied with the excitation wavelengths. When the excitation wavelength was 256 nm, the ⁵D₄→⁷F₀,⁵D₇→⁷F₀,⁵G₂→⁷F₀,⁵L₆→⁷F₀,⁵D₀→⁷F₀,⁵D₀→⁷F₁,⁵D₀→⁷F₂,⁵D₀→⁷F₃and⁵D₀→⁷F₄ transitions from Eu³⁺ ions in Au/Y₂O₃:Eu³⁺ were observed. When the excitation wavelength was 378 nm, the plasmon resonance peak from Au nanoparticles was observed.The Pt/Y₂O₃:Eu³⁺ composite nanotubes were prepared same as Au/Y₂O₃:Eu³⁺. Then characterize its morphology and feature. The effects of the Pt content on the photoluminescence properties were investigated in detail. In the excitation spectra of Pt/Y₂O₃:Eu³⁺ monitored at 615 nm, the 7F0→5H3 transition from Eu³⁺ decreased with increasing Pt content. In the emission spectra of Pt/Y₂O₃:Eu³⁺ with different Pt contents excited at 395 nm, the 5D0→7F2 emission at 634 nm was split into two sub-bands. When the excitation wavelength were set at 255 nm, the luminescence was dominated by the 5D0→7F2 transition. However, when the excitation wavelength was set at 534 nm, a broad emissions band centered at 590 nm was observed.In addition, for the surface-enhanced Raman scattering（SERS） study. 4-ATP was chosen as the model molecule to examine the performance of the Au/Y₂O₃:Eu³⁺ and Pt/Y₂O₃:Eu³⁺ composite nanotubes as SERS substrates. The relative intensities of the SERS spectra enhanced with the increase of Au and Pt content.