Interfacial potassium induced enhanced Raman spectroscopy for single-crystal TiO2 Nanowhisker

Fan Pan, Guobing Zhou, Liangliang Huang, Wei Li, Mingshen Lin, Chang Liu

Research output: Contribution to journalArticle

Abstract

Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy (SERS) properties. For TiO 2 based SERS substrates, maintaining a good crystallinity is critical to achieve excellent Raman scattering. At elevated temperatures (> 600 °C), the phase transition from anatase to rutile TiO 2 could result in a poor SERS performance. In this work, we report the successful synthesis of TiO 2 nanowhiskers with excellent SERS properties. The enhancement factor, an index of SERS performance, is 4.96 × 10 6 for methylene blue molecule detecting, with a detection sensitivity around 10 −7 mol·L −1. Characterizations, such as XRD, Raman, TEM, UV–vis and Zeta potential measurement, have been performed to decrypt structural and chemical characteristics of the newly synthesized TiO 2 nanowhiskers. The photo absorption onset of MB adsorbed TiO 2 nanowhiskers was similar to that of bare TiO 2 nanowhiskers. In addition, no new band was observed from the UV–vis of MB modified TiO 2 nanowhiskers. Both results suggest that the high enhancement factor cannot be explained by the charge-transfer mechanism. With the support of ab initio density functional theory calculations, we reveal that interfacial potassium is critical to maintain thermal stability of the anatase phase up to 900 °C. In addition, the deposition of potassium results in a negatively charged TiO 2 nanowhisker surface, which favors specific adsorption of methylene blue molecules and significantly improves SERS performance via the electrostatic adsorption effect.

Original languageEnglish
JournalChinese Journal of Chemical Engineering
Early online date25 Oct 2019
DOIs
Publication statusE-pub ahead of print - 25 Oct 2019

Bibliographical note

© 2019, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Funding: Natural Science Foundation of China (21878143, 21476106, and 21838004), Joint Re-search Fund for Overseas Chinese Scholars and Scholars in Hong Kong and Macao Young Scholars (21729601), the fund of State Key Laboratory of Materials-Oriented Chemical Engineering (ZK201702, KL16-01), the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the U.S. National Science Foundation (NSF) Grant No. CHE-1710102.

Keywords

  • SERS
  • TiO nanowhisker
  • potassium induced

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