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Alternative to Noble Metal Substrates: Metallic and Plasmonic Ti₃O₅ Hierarchical Microspheres for Surface Enhanced Raman Spectroscopy

Li, Yahui, Bai, Hua, Zhai, Junfeng, Yi, Wencai, Li, Junfang, Yang, Haifeng, Xi, Guangcheng
Analytical chemistry 2019 v.91 no.7 pp. 4496-4503
Raman spectroscopy, corrosion, gold, microparticles, nanosilver, oxidation, photocatalysis, semiconductors, silver, temperature, titanium dioxide
Compared with noble metals, improving the sensitivity of semiconducting surface-enhanced Raman scattering (SERS) substrates is of great significance to their fundamental research and practical application of Raman spectroscopy. In this paper, it is found that the SERS sensitivity is increased by 10 000 times by reducing the semiconducting TiO₂ microspheres to quasi-metallic Ti₃O₅ microspheres. Its lowest detectable limit is up to 10–¹⁰ M, which may be the best among the non-noble metal substrates and even reaches or exceeds certain Au/Ag nanostructures to the best of our knowledge. This new type of non-noble metal SERS substrate breaks through the bottleneck of poor stability of conventional semiconductor substrate and can withstand high temperature oxidation at 200 °C and strong acid–base corrosion without performance degradation. Benefiting from its excellent ability of visible-light photocatalytic degradation of organic molecules, the substrate can be reused. Moreover, the new material also exhibits excellent photothermal conversion properties.