Defect-Engineering in MoS2 Layers for Surface Enhanced Raman Scattering

Antonio Brancato; Marcello Condorelli; Vittorio Scardaci; Enza Fazio; Giuseppe Forte; Luisa D'urso; Giuseppe Compagnini

doi:10.53941/ps.2026.100005

Abstract

Surface-enhanced Raman scattering (SERS) offers exceptional molecular sensitivity, but the instability and poor reproducibility of noble metal substrates limit its practical use. Here, we investigate low-cost, non-plasmonic alternatives based on two-dimensional molybdenum disulfide (MoS₂). We introduce a reagent-free, pulsed-laser irradiation in liquid protocol to controllably engineer defects and induce the metallic 1T phase within MoS₂, thereby tailoring its electronic structure through sulfur vacancies. Laser-modified MoS₂ displays markedly enhanced SERS activity relative to unmodified 2H-MoS₂; the enhancement correlates with increased density of defect sites and the presence of the conducting 1T phase, which together promote more efficient substrate-adsorbate charge transfer. By using 4-mercaptobenzoic acid (4-MBA) as a probe molecule, laser-modified MoS₂ shows a SERS enhancement factor of ≈10⁵ compared with pristine 2H-MoS₂ under 532 nm excitation. The experimental results were further validated by density functional theory calculations, which show a better match of the energy level of MoS₂ 1T with our probe molecule, supporting the ongoing research aimed at designing novel SERS substrates. Our results demonstrate that phase and defect engineering in 2D materials provide a robust route to reproducible, non-plasmonic SERS substrates, offering a scalable alternative to noble metals for sensitive chemical and biosensing applications.

References

1.
Schmidt, M.M.; Brolo, A.G.; Lindquist, N.C. Single-Molecule Surface-Enhanced Raman Spectroscopy: Challenges, Opportunities, and Future Directions. ACS Nano 2024, 18, 25930–25938. https://doi.org/10.1021/ACSNANO.4C09483.
2.
Matikainen, A.; Nuutinen, T.; Itkonen, T.; et al. Atmospheric oxidation and carbon contamination of silver and its effect on surface-enhanced Raman spectroscopy (SERS). Sci. Rep. 2016, 6, 37192. https://doi.org/10.1038/srep37192.
3.
Zhao, X.; Wang, Y.; Liu, Y.; et al. Gradient Nanostructures and Machine Learning Synergy for Robust Quantitative Surface-Enhanced Raman Scattering. Adv. Sci. 2025, 12, 2501793. https://doi.org/10.1002/ADVS.202501793.
4.
Ozdemir, R.; Hukum, K.O.; Usta, H.; et al. Organic and inorganic semiconducting materials-based SERS: Recent developments and future prospects. J. Mater. Chem. C Mater. 2024, 12, 15276–15309. https://doi.org/10.1039/D4TC02391A.
5.
Krajczewski, J.; Michałowska, A.; Čtvrtlík, R.; et al. The battle for the future of SERS—TiN vs. Au thin films with the same morphology. Appl. Surf. Sci. 2023, 618, 156703. https://doi.org/10.1016/J.APSUSC.2023.156703.
6.
Lan, L.; Gao, Y.; Fan, X.; et al. The origin of ultrasensitive SERS sensing beyond plasmonics. Front. Phys. 2021, 16, 43300. https://doi.org/10.1007/S11467-021-1047-Z.
7.
Rani, D.; Patel, S.; Austeria, P.M.; et al. Surface-Enhanced Raman Spectroscopy (SERS) Chemical Enhancement in the Vibronically Coupled Langmuir Layer of Mixed Dichalcogenide 1T-MoSSe with Adsorbed R6G. J. Phys. Chem. C 2023, 127, 3131–3141. https://doi.org/10.1021/ACS.JPCC.2C08705.
8.
Liu, H.; Li, Q.; Ma, Y.; et al. Study of charge transfer contribution in Surface-Enhanced Raman scattering (SERS) based on indium oxide nanoparticle substrates. Spectrochim. Acta A Mol. Biomol. Spectrosc. 2023, 303, 123168. https://doi.org/10.1016/J.SAA.2023.123168.
9.
Zheng, Z.; Cong, S.; Gong, W.; et al. Semiconductor SERS enhancement enabled by oxygen incorporation. Nat. Commun. 2017, 8, 1993. https://doi.org/10.1038/S41467-017-02166-Z.
10.
Zhang, M.; Wang, Y.; Ma, Y.; et al. Study of charge transfer effect in Surface-Enhanced Raman scattering (SERS) by using Antimony-doped tin oxide (ATO) nanoparticles as substrates with tunable optical band gaps and free charge carrier densities. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2021, 264, 120288. https://doi.org/10.1016/J.SAA.2021.120288.
11.
Gan, X.; Lee, L.Y.S.; Wong, K.Y.; et al. 2H/1T Phase Transition of Multilayer MoS₂ by Electrochemical Incorporation of S Vacancies. ACS Appl. Energy Mater. 2018, 1, 4754–4765. https://doi.org/10.1021/ACSAEM.8B00875.
12.
Sun, S.; Zheng, J.; Sun, R.; et al. Defect-Rich Monolayer MoS₂ as a Universally Enhanced Substrate for Surface-Enhanced Raman Scattering. Nanomaterials 2022, 12, 896. https://doi.org/10.3390/NANO12060896.
13.
Nair, P.R.; Ramirez, C.R.S.; Pinilla, M.A.G.; et al. Black titanium dioxide nanocolloids by laser irradiation in liquids for visible light photo-catalytic/electrochemical applications. Appl. Surf. Sci. 2023, 623, 157096. https://doi.org/10.1016/J.APSUSC.2023.157096.
14.
Fazio, E.; Gökce, B.; De Giacomo, A.; et al. Nanoparticles Engineering by Pulsed Laser Ablation in Liquids: Concepts and Applications. Nanomaterials 2020, 10, 2317. https://doi.org/10.3390/NANO10112317.
15.
Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 1996, 54, 11169. https://doi.org/10.1103/PhysRevB.54.11169.
16.
Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 1999, 59, 1758. https://doi.org/10.1103/PhysRevB.59.1758.
17.
Perdew, J.P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865. https://doi.org/10.1103/PhysRevLett.77.3865.
18.
Dion, M.; Rydberg, H.; Schröder, E.; et al. Density Functional for General Geometries. Phys. Rev. Lett. 2004, 92, 246401. https://doi.org/10.1103/PhysRevLett.92.246401.
19.
Román-Pérez, G.; Soler, J.M. Efficient Implementation of a van der Waals Density Functional: Application to Double-Wall Carbon Nanotubes. Phys. Rev. Lett. 2009, 103, 096102. https://doi.org/10.1103/PhysRevLett.103.096102.
20.
Tang, W.; Sanville, E.; Henkelman, G. A grid-based Bader analysis algorithm without lattice bias. J. Phys. Condens. Matter 2009, 21, 084204. https://doi.org/10.1088/0953-8984/21/8/084204.
21.
Luo, T.; Chen, X.; Wang, L.; et al. Green laser irradiation-stimulated fullerene-like MoS₂ nanospheres for tribological applications. Tribol. Int. 2018, 122, 119–124. https://doi.org/10.1016/J.TRIBOINT.2018.02.040.
22.
Compagnini, G.; Sinatra, M.G.; Messina, G.C.; et al. Monitoring the formation of inorganic fullerene-like MoS₂ nanostructures by laser ablation in liquid environments. Appl. Surf. Sci. 2012, 258, 5672–5676. https://doi.org/10.1016/J.APSUSC.2012.02.053.
23.
Ibrahim, K.; Novodchuk, I.; Mistry, K.; et al. Laser-Directed Assembly of Nanorods of 2D Materials. Small 2019, 15, 1904415. https://doi.org/10.1002/SMLL.201904415.
24.
Zamharir, S.G.; Karimzadeh, R.; Aboutalebi, S.H. Laser-assisted tunable optical nonlinearity in liquid-phase exfoliated MoS₂ dispersion. Appl Phys A Mater Sci Process 2018, 124, 692. https://doi.org/10.1007/S00339-018-2115-2.
25.
Mosleh, A.; Alher, M.A.; Cousar, L.; et al. Transmission spectra of some transition metal dichalcogenides. II. Group VIA: trigonal prismatic coordination. J. Phys. C: Solid. State Phys. 1972, 5, 3540. https://doi.org/10.1088/0022-3719/5/24/016.
26.
Kong, G.; Du, X.; Cai, X.; et al. Recycling Molybdenum Oxides from Waste Molybdenum Disilicides: Oxidation Experimental Study and Photocatalytic Properties. Oxid. Met. 2019, 92, 1–12. https://doi.org/10.1007/S11085-019-09909-X.
27.
Stavrou, M.; Chazapis, N.; Nikoli, E.; et al. Crystalline Phase Effects on the Nonlinear Optical Response of MoS₂ and WS₂ Nanosheets. ACS Appl. Nano Mater. 2023, 5, 16674–16686. https://doi.org/10.1021/acsanm.2c03709.
28.
Han, B.; Hu, Y.H. MoS₂ as a co-catalyst for photocatalytic hydrogen production from water. Energy Sci. Eng. 2016, 4, 285–304. https://doi.org/10.1002/ESE3.128.
29.
Khan, Y.; Obaidulla, S.M.; Habib, M.R.; et al. Anomalous photoluminescence quenching in DIP/MoS₂ van der Waals heterostructure: Strong charge transfer and a modified interface. Appl. Surf. Sci. 2020, 530, 147213. https://doi.org/10.1016/J.APSUSC.2020.147213.
30.
Li, H.; Zhang, Q.; Yap, C.C.R.; et al. From Bulk to Monolayer MoS₂: Evolution of Raman Scattering. Adv. Funct. Mater. 2012, 22, 1385–1390. https://doi.org/10.1002/ADFM.201102111.
31.
Chang, H.P.; Hofmann, M.; Hsieh, Y.P.; et al. Correlation of grain orientations and the thickness of gradient MoS₂ films. RSC Adv. 2021, 11, 34269–34274. https://doi.org/10.1039/D1RA05982C.
32.
Ye, F.; Chang, D.; Ayub, A.; et al. Synthesis of Two-Dimensional Plasmonic Molybdenum Oxide Nanomaterials by Femtosecond Laser Irradiation. Chem. Mater. 2021, 33, 4510–4521. https://doi.org/10.1021/ACS.CHEMMATER.1C00732.
33.
Yin, Y.; Miao, P.; Zhang, Y.; et al. Significantly Increased Raman Enhancement on MoX2 (X = S, Se) Monolayers upon Phase Transition. Adv. Funct. Mater. 2017, 27, 1606694. https://doi.org/10.1002/ADFM.201606694.
34.
Li, B.; Jiang, L.; Li, X.; et al. Preparation of Monolayer MoS₂ Quantum Dots using Temporally Shaped Femtosecond Laser Ablation of Bulk MoS₂ Targets in Water. Sci. Rep. 2017, 7, 11182. https://doi.org/10.1038/S41598-017-10632-3.
35.
Tran, H.N.; Park, S.; Wibowo, F.T.A.; et al. 17% Non-Fullerene Organic Solar Cells with Annealing-Free Aqueous MoOx. Adv. Sci. 2020, 7, 2002395. https://doi.org/10.1002/ADVS.202002395.
36.
Xu, Q.; Li, X.; Wu, L.; et al. Enlarged Interlayer Spacing of Marigold-Shaped 1T-MoS₂ with Sulfur Vacancies via Oxygen-Assisted Phosphorus Embedding for Rechargeable Zinc-Ion Batteries. Nanomaterials 2023, 13, 1185. https://doi.org/10.3390/NANO13071185.
37.
Mouloua, D.; Rajput, N.S.; Lejeune, M.; et al. Giant Photodegradation Rate Enabled by Vertically Grown 1T/2H MoS₂ Catalyst on Top of Silver Nanoparticles. Adv. Energy Sustain. Res. 2024, 5, 2400213. https://doi.org/10.1002/AESR.202400213.
38.
Gu, C.; Li, D.; Zeng, S.; et al. Synthesis and defect engineering of molybdenum oxides and their SERS applications. Nanoscale 2021, 13, 5620–5651. https://doi.org/10.1039/D0NR07779H.
39.
Ho, C.H.; Lee, S. SERS and DFT investigation of the adsorption behavior of 4-mercaptobenzoic acid on silver colloids. Colloids Surf. A Physicochem. Eng. Asp. 2015, 474, 29–35. https://doi.org/10.1016/J.COLSURFA.2015.03.004.
40.
Le Ru, E.C.; Etchegoin, P.G. Quantifying SERS enhancements. MRS Bull. 2013, 38, 631–640. https://doi.org/10.1557/MRS.2013.158.
41.
Pramanik, A.; Gao, Y.; Gates, K.; et al. Giant Chemical and Excellent Synergistic Raman Enhancement from a 3D MoS_2−xO_x−Gold Nanoparticle Hybrid. ACS Omega 2019, 4, 11112–11118. https://doi.org/10.1021/acsomega.9b00866.
42.
Yin, Y.; Li, C.; Yan, Y.; et al. MoS₂-Based Substrates for Surface-Enhanced Raman Scattering: Fundamentals, Progress and Perspective. Coatings 2022, 12, 360. https://doi.org/10.3390/COATINGS12030360.
43.
Er, E.; Hou, H.-L.; Criado, A.; et al. High-Yield Preparation of Exfoliated 1T-MoS 2 with SERS Activity. Chem. Mater. 2019, 31, 5725–5734. https://doi.org/10.1021/acs.chemmater.9b01698.
44.
Shim, S.; Stuart, C.M.; Mathies, R.A. Resonance Raman cross-sections and vibronic analysis of rhodamine 6G from broadband stimulated Raman spectroscopy. Chemphyschem 2008, 9, 697–699. https://doi.org/10.1002/CPHC.200700856.
45.
Angeloni, L.; Smulevich, G.; Marzocchi, M.P. Resonance Raman spectrum of crystal violet. J. Raman Spectrosc. 1979, 8, 305–310. https://doi.org/10.1002/JRS.1250080603.

Scilight Press

Author Information

Abstract

Graphical Abstract

Keywords

References

About Scilight

Journals

Publishing Policies

Contact Us