Highly sensitive and selective detection of trace nitrogen dioxide (NO2) in a complex outdoor air environment is an urgent need to guarantee human health and a beautiful environment. The effective combination of heterostructure and light irradiation is an important strategy to achieve high-performances gas sensors. However, the effect of light irradiation on gas-sensitive properties of heterostructure materials is not yet clear, and it is urgent to clarify the relationship between light irradiation and heterostructure for gas-sensing materials. Herein, a 530 nm-light-assisted Au–MoS2 gas sensor with a low detection limit as well as robust antihumidity interference ability is developed through introducing the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (NPs). Under 530 nm light illumination, a Au–MoS2 gas sensor can achieve limit detection of NO2 as low as 10 ppb without operating temperature along with robust antihumidity ability. The optical simulation and experimental results show that the modification of MoS2 by Au NPs (diameter: 30 nm) combined with the matching light-assisted (530 nm) gas detection mode can make MoS2 fully absorb visible light and effectively improve the extinction cross section by taking full advantage of the LSPR effect, which is the primary reason for the enhanced performances of a MoS2-based gas sensor. This work provides theoretical and experimental guidance for gas sensors to effectively enhance the ability of gas detection by means of the light-assisted mode at room temperature, which opens up a unique approach to design high-performance gas sensors for trace-level gas detection.

Surface lattice resonances (SLRs) arising in metal nanostructure arrays have shown tremendous application prospects in the field of plasmonic biosensing. However, these SLRs still suffer from poor optical properties, such as broad linewidth or weak resonance intensity that is especially excited under normal incidence and asymmetric environments, which hinder further practical applications. Herein, we theoretically propose an effective strategy to tailor the SLRs performance of metal nanostructure arrays by introducing a dielectric nanocavity. Originating from the strong interference between the in-plane lattice resonance mode and plasmonic gap cavity modes, the dielectric nanocavity-mediated gold nanostructure arrays exhibit both narrow spectral features with a linewidth of ∼8.2 nm and strong resonance intensity with absorbance amplitude exceeding 95%, even though under normal incidence and asymmetric environment excitation. The simulation results then show that the sensitivity and the figure of merit can reach up to 527.5 nm RIU−1 and 64.3, respectively, as for plasmonic refractive index sensing. This work not only paves the way toward the achievement of effective control of in-plane SLRs, but also provides a potentially attractive candidate for the development of high-efficiency plasmonic sensors.

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Anapole modes supported by the well-designed dielectric nanostructure have attracted extensive concerns in the field of nanophotonic applications owing to its unique strong near-field enhancement and nonradiative far-field scattering characteristics, yet it is still difficult to achieve high Q-factor resonance features with narrow linewidth. In this work, a periodic slotted silicon nanodisk array is theoretically proposed to realize narrow linewidth and high Q-factor resonance in the near-infrared wavelength range. Through introducing the coupling between the anapole modes in the single dielectric nanostructure and the diffractive wave mode arisen from the periodic array, the as-designed dielectric nanostructure synchronously manifests excellent spectral features with a bandwidth as narrow as about 2.0 nm, a large Q-factor of 599, perfect transmission amplitude attaining 96% and relatively high electric field intensity (> 2809 times) in the middle of the slotted silicon nanodisk. The as-designed nanostructure possessing these outstanding optical features can work as a high-efficiency refractive-index sensor, whose sensitivity can reach 161.5 nm/RIU with its figure of merit attaining 80.8 RIU−1, efficiently distinguishing an index change of less than 0.01. The proposed slotted silicon nanodisk array exhibits tremendous potential for expanding the application such as label-free biochemical sensing, plasmonic refractive index sensing and surface enhancement spectroscopy.