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Bhatnagar M, Woźniak T, Kipczak Ł, Zawadzka N, Olkowska-Pucko K, Grzeszczyk M, Pawłowski J, Watanabe K, Taniguchi T, Babiński A, Molas MR. Temperature induced modulation of resonant Raman scattering in bilayer 2H-MoS 2. Sci Rep 2022; 12:14169. [PMID: 35986062 PMCID: PMC9391345 DOI: 10.1038/s41598-022-18439-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/11/2022] [Indexed: 11/15/2022] Open
Abstract
The temperature evolution of the resonant Raman scattering from high-quality bilayer 2H-MoS[Formula: see text] encapsulated in hexagonal BN flakes is presented. The observed resonant Raman scattering spectrum as initiated by the laser energy of 1.96 eV, close to the A excitonic resonance, shows rich and distinct vibrational features that are otherwise not observed in non-resonant scattering. The appearance of 1st and 2nd order phonon modes is unambiguously observed in a broad range of temperatures from 5 to 320 K. The spectrum includes the Raman-active modes, i.e. E[Formula: see text]([Formula: see text]) and A[Formula: see text]([Formula: see text]) along with their Davydov-split counterparts, i.e. E[Formula: see text]([Formula: see text]) and B[Formula: see text]([Formula: see text]). The temperature evolution of the Raman scattering spectrum brings forward key observations, as the integrated intensity profiles of different phonon modes show diverse trends. The Raman-active A[Formula: see text]([Formula: see text]) mode, which dominates the Raman scattering spectrum at T = 5 K quenches with increasing temperature. Surprisingly, at room temperature the B[Formula: see text]([Formula: see text]) mode, which is infrared-active in the bilayer, is substantially stronger than its nominally Raman-active A[Formula: see text]([Formula: see text]) counterpart.
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Affiliation(s)
- Mukul Bhatnagar
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland.
| | - Tomasz Woźniak
- Department of Semiconductor Materials Engineering, Wrocław University of Science and Technology, ul. Wybrzeże Wyspiańskiego 27, 50-370, Wrocław, Poland
| | - Łucja Kipczak
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Natalia Zawadzka
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Katarzyna Olkowska-Pucko
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Magdalena Grzeszczyk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Jan Pawłowski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Adam Babiński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland
| | - Maciej R Molas
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093, Warsaw, Poland.
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Sindhu AS, Shinde NB, Harish S, Navaneethan M, Eswaran SK. Recoverable and reusable visible-light photocatalytic performance of CVD grown atomically thin MoS 2 films. CHEMOSPHERE 2022; 287:132347. [PMID: 34582929 DOI: 10.1016/j.chemosphere.2021.132347] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 09/07/2021] [Accepted: 09/22/2021] [Indexed: 05/14/2023]
Abstract
The decomposition of water pollutants including industrial dyes and chemicals via photocatalytic decontamination is one of the major investigated problems in recent years. Two-dimensional molybdenum disulfide (MoS2) layers have shown great promise as an efficient visible-light photocatalyst owing to its numerous active sites and large surface area. In this study, atomically thin MoS2 films of different thicknesses from monolayer to five-layer and ten layers were fabricated on sapphire substrates using chemical vapor deposition (CVD). We demonstrate that these MoS2 thin films can be used as a photocatalyst to degrade Methylene Blue (MB) dye and can be recovered completely with utmost structural and chemical stability. Under visible-light irradiation, the MB absorption peak completely disappears with ∼95.6% of degradation after 120 min. We also demonstrate the reusability of the MoS2 thin films without significantly losing the photocatalytic activity even after 5-cycles of degradation studies. The chemical and structural stability of the MoS2 films after 5-cycles of degradation studies were affirmed using various spectroscopic studies. Our findings suggest that the MB degradation efficiency increases from 19.01% to 98.46% with an increase in pH from 4 to 14. Our approach may facilitate a further design of other transition metal dichalcogenides-based recoverable photocatalysts for industrial applications.
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Affiliation(s)
- Abhishek Singh Sindhu
- 2D Materials and Devices Laboratory (2DML), Sir C. V. Raman Research Park, Department of Physics and Nanotechnology, SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India
| | - Nitin Babu Shinde
- 2D Materials and Devices Laboratory (2DML), Sir C. V. Raman Research Park, Department of Physics and Nanotechnology, SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India
| | - S Harish
- Functional Materials and Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India
| | - M Navaneethan
- Functional Materials and Devices Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India; Nanotechnology Research Centre (NRC), SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India
| | - Senthil Kumar Eswaran
- 2D Materials and Devices Laboratory (2DML), Sir C. V. Raman Research Park, Department of Physics and Nanotechnology, SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India; Nanotechnology Research Centre (NRC), SRM Institute of Science and Technology (SRMIST), Kattankulathur, 603203, Chennai, India.
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