Phosphate glasses containing silver nanoparticles for applications in plasmonics

Author(s)

Thiago Israel Rubio

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2021-08-10

Examining board members

Danilo Manzani; Gustavo Fernandes Souza Andrade; Hermi Felinto de Brito

• Advisor: Danilo Manzani

Abstract

Silver nanoparticles (Ag-NPs) are species that exhibit the surface plasmon resonance (SPR) effect. In this work, such plasmons were utilized in two different applications: the enhancement of Raman spectra via surface-enhanced Raman scattering (SERS), and the degradation of organic molecules using photocatalysis. To achieve these purposes, two novel glass compositions were synthesized, one using lead phosphate (PBTN), and other using sodium phosphate (NBTN). Both contain titanium oxide in their compositions, and the effect of the insertion of this compound on the thermal properties and chemical structure of the glasses was investigated through thermal analysis, Raman spectroscopy, X-ray diffraction, and photoluminescence spectroscopy. Silver nanoparticles were, then, synthesized on the surface of NBTN glasses using Na+/Ag+ ion exchange followed by controlled thermal treatment, and electron microscopy techniques, alongside UV-visible spectroscopy were employed to confirm the synthesis. SERS experiments were conducted using crystal violet as analyte, and it was possible to detect it on the glass surface up to a lower limit of 10-6 mol/L using NBTN-Ag120 sample. Photocatalysis tests were run using the glass samples in powder and bulk forms. The photodegradation of methylene blue was assessed. While in the former, 57.8% of degradation was obtained, in the latter, an even greater amount of dye was degraded, 68.3%. In both cases, tests using no glass sample and using NBTN glass containing no Ag-NPs were conducted. It was proven that the vitreous substrate acts as a photocatalyst on its own. Moreover, the degradation percentage was greater when the nanoparticles were present in the material, showing that plasmonic mechanisms were responsible for the enhancement in the overall process. The solid materials developed during this work and herein presented are good candidates for devices in both fields of sensing and photocatalysis. (AU)

• FAPESP's process: 19/16230-1 - Plasmonic photocatalysis in oxide glasses containing silver nanoparticles
• Grantee: Thiago Israel Rubio
• Support Opportunities: Scholarships in Brazil - Master