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Published on: March 20, 2019
Engineering nanopore in monolayer WS2 for single-molecule imaging on the atomic-scale flat 2D surfaces
Haoqi He1, Mingchuang Zhao1, Hengyue Xu2
1Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Institute of Materials Research, Center of Double Helix, Guangdong Provincial Key Laboratory of Thermal Management Engineering and Materials, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, P. R. China.
Engineered nanopores in two-dimensional tungsten disulfide (WS₂) create dangling bonds, significantly enhancing molecular adsorption and enabling ultrasensitive surface-enhanced Raman scattering (SERS) detection of single molecules.
Area of Science:
- Materials Science
- Nanotechnology
- Spectroscopy
Background:
- Two-dimensional (2D) materials like WS₂ lack dangling bonds, limiting their molecular adsorption capabilities for surface-enhanced Raman scattering (SERS) applications.
- Defects are crucial for enhancing molecular adsorption and optimizing SERS performance in 2D materials.
Purpose of the Study:
- To engineer defects (nanopores) in monolayer WS₂ to improve molecular adsorption and SERS sensitivity.
- To investigate the role of nanopores in modulating the WS₂ bandgap and enhancing Raman signal amplification.
- To achieve single-molecule SERS detection using defect-engineered WS₂.
Main Methods:
- Controlled plasma treatments to create nanopores in monolayer WS₂.
- Photoluminescence spectroscopy to observe bandgap modulation with increasing defect density.
- Surface-enhanced Raman scattering (SERS) measurements using rhodamine 6G (R6G) as a probe molecule.
- SERS mapping to visualize molecular adsorption sites.
Main Results:
- Nanopores introduced dangling bonds, enhancing molecular adsorption and enrichment.
- Defect density correlated with a blue shift in photoluminescence, indicating bandgap modulation.
- Localized electromagnetic fields around nanopores amplified Raman signals.
- Achieved single-molecule SERS detection limit of 1 × 10⁻²⁰ M for R6G.
- SERS mapping confirmed nanopores as active adsorption sites.
Conclusions:
- Defect engineering via nanopore creation is a pioneering method for developing ultrasensitive 2D SERS substrates.
- Nanoporous WS₂ demonstrates significant potential for single-molecule detection applications.
- The study advances the understanding of SERS mechanisms on defect-engineered 2D materials.
