Regulation of hot spots exhibits excellent potential in many applications including nanolasers, energy harvesting, sensing, and subwavelength imaging. Here, hat-shaped hierarchical nanostructures with different space curvatures have been proposed to enhance hot spots for facilitating surface-enhanced Raman scattering (SERS) and plasmon-driven catalysis applications. These novel nanostructures comprise two layers of metal nanoparticles separated by hat-shaped MoS2 films. The fabrication of this hybrid structure is based on the thermal annealing and thermal evaporation of self-assembled polystyrene spheres, which are convenient to control the metal particle size and the curvature of hat-shaped nanostructures. Based on the narrow gaps produced by the MoS2 films and the curvature of space, the constructed platform exhibits superior SERS capability and achieves ultrasensitive detection for toxic molecules. Furthermore, the surface catalytic conversion of p-nitrothiophenol (PNTP) to p, p′-dimercaptobenzene (DMAB) was in situ monitored by the SERS substrate. The mechanism governing this regulation of hot spots is also investigated via theoretical simulations.
MoS2-based heterostructures have received increasing attention for not only surface-enhanced Raman scattering (SERS) but also for enhanced photoelectrocatalytic (PEC) performance. This study presents a hydrothermal method for preparing vertical MoS2 nanosheets composed of in situ grown AuNPs with small size and chemically reduced AgNPs with large size to achieve the synergistic enhancement of SERS and PEC properties owing to the size effect of the plasmonic structure. Compared with pristine MoS2 nanosheets and unitary AuNPs or AgNPs composited with MoS2 nanosheets, the ternary heterostructure exhibited the strongest electromagnetic field and surface plasmon coupling, which was confirmed by finite-difference time-domain (FDTD) simulation and absorption spectra. In addition, the experimental results confirmed the outstanding SERS enhancement with an EF of 1.1×109, and the most efficient hydrogen evolution reaction (HER) activity with a sensitive photocurrent response, attributing to the multiple surface plasmonic coupling effects of the Au-Ag bimetal and efficient charge-transfer process between MoS2 and the bimetal. That is, it provides a robust method for developing multi-size bimetal-semiconductor complex nanocomposites for high-performance SERS sensors and PEC applications.
The weak plasmonic coupling intensity in an aluminum (Al) nanostructure has limited potential applications in excellent low-cost surface-enhanced Raman scattering (SERS) substrates and light harvesting. In this report, we aim to elevate the plasmonic coupling intensity by fabricating an Al nanoparticle (NP)−film system. In the system, the Al NP are fabricated directly on different Al film layers, and the nanoscale-thick alumina interlayer obtained between neighboring Al films acts as natural dielectric gaps. Interestingly, as the number of Al film layers increase, the plasmonic couplings generated between the Al NP and Al film increase as well. It is demonstrated that the confined gap plasmon modes stimulated in the nanoscale-thick alumina region between the adjacent Al films contribute significantly to elevating the plasmonic coupling intensity. The finite-difference time-domain (FDTD) method is used to carry out the simulations and verifies this result.
Oxygen evolution reaction (OER), as an essential process in water decomposition and air batteries, has received increasing attention in the context of clean energy production and efficient energy storage. With...
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