Significantly increased Raman enhancement on defect-rich O-incorporated 1T-MoS 2 nanosheets
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Significantly increased Raman enhancement on defectrich O-incorporated 1T-MoS2 nanosheets Xiaoyu Zhou1, Di Wu1, Zhen Jin1, Xiaojie Song1, Xiufang Wang1,*
1 2
, and Steven L. Suib2,*
School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei Anhui 230601, China Institute of Materials Science and Department of Chemistry, University of Connecticut, U-3136, U-3060, Storrs, Mansfield, CT 06269, USA
Received: 1 May 2020
ABSTRACT
Accepted: 26 August 2020
Improving charge transfer is the key to the performance of non-noble metal semiconductor-based surface enhanced Raman scattering (SERS) substrates. In this work, the O-incorporated 1T-MoS2 nanosheets with rich sulfur defects (IDMoS2) are obtained by simple calcination of 1T-MoS2 nanosheets in air atmosphere. Using rhodamine 6G (R6G) as typical probe molecules, ID-MoS2 nanosheets show ultrahigh Raman enhancement effects with an enhancement factor of 1.24 9 107 due to sulfur defects and O incorporation in the 1T-MoS2 lattice. First-principle density functional theory calculations suggest that the existence of sulfur defects and O incorporation significantly increase the Fermi energy level (Ef) and electronic density of states of ID-MoS2. Moreover, O incorporation can enhance the interactions between the substrate and the adsorbed molecules through electrostatic and hydrogen bonding. All these improve the charge transfer resonance and result in the remarkable SERS activity of ID-MoS2 nanosheets. This is the first study on the increasing SERS performance of semiconductor substrates by simultaneously employing defect and dopant incorporation. This study provides an approach to optimize the performance of semiconductor-based SERS substrates.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Avinash Dongare. Xiaoyu Zhou and Di Wu have contributed equally to this work.
Address correspondence to E-mail: [email protected]; [email protected]
https://doi.org/10.1007/s10853-020-05172-7
J Mater Sci
Introduction SERS has been intensively studied as an extremely important analytical technique, which has been widely utilized in various chemical and biological fields [1–5]. The sensitivity of SERS depends on the properties of substrate materials. The conventional nanostructured noble metal materials with strong localized surface plasmon resonance (for example, Au and Ag) are the most broadly applied SERS substrates [6–9]. However, the poor uniformity, high cost and poor biocompatibility of noble metal nanomaterials unavoidably confine large-scale applications [10–12]. In order to find better SERS candidates and acquire superior Raman scattering enhancement, research on SERS substrates is increasingly focused on low-cost non-noble metal semiconductor-based substrate nanomaterials, such as MoO2 [13–15], W18O49 [16], MoS2 [17, 18] and WO3-X [19, 20]. Nevertheless, although these semiconductor materials have displayed a degree of SERS performance, the enhancement factors are still very low. These systems do not meet the
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