2D materials hold great potential for designing novel electronic and optoelectronic devices. However, 2D material can only absorb limited incident light. As a representative 2D semiconductor, monolayer MoS can only absorb up to 10% of the incident light in the visible, which is not sufficient to achieve a high optical-to-electrical conversion efficiency. To overcome this shortcoming, a "gap-mode" plasmon-enhanced monolayer MoS fluorescent emitter and photodetector is designed by squeezing the light-field into Ag shell-isolated nanoparticles-Au film gap, where the confined electromagnetic field can interact with monolayer MoS . With this gap-mode plasmon-enhanced configuration, a 110-fold enhancement of photoluminescence intensity is achieved, exceeding values reached by other plasmon-enhanced MoS fluorescent emitters. In addition, a gap-mode plasmon-enhanced monolayer MoS photodetector with an 880% enhancement in photocurrent and a responsivity of 287.5 A W is demonstrated, exceeding previously reported plasmon-enhanced monolayer MoS photodetectors.

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Plasmon-mediated photocatalytic water splitting has attracted extensive attention due to its bright future in using visible light, but the enhancement mechanism is still unclear, and the efficiency remains low. Herein, a dual-plasmonic-antenna strategy that allows efficient generation of energetic hot electrons and strong electromagnetic fields simultaneously has been developed to boost the photocatalytic hydrogen evolution reaction (HER). Au@CdS core–shell nanoparticles are assembled on Ag@SiO2 shell-isolated nanoparticles, forming dual-plasmonic-antenna nanocomposites. Transient absorption spectroscopic experiments and electromagnetic field simulations demonstrate that both hot-electron transfer and plasmon-induced resonance energy transfer exist in this system. The Au@CdS antenna can generate energetic hot electrons to trigger the HER, while the Ag@SiO2 antenna produces strong electromagnetic fields to promote the generation and separation of hot carriers, thus significantly improving the HER performance under visible light irradiation. Such a dual-plasmonic-antenna concept overcomes the intrinsic limitation of traditional plasmonic photocatalytic materials and offers unique opportunities to develop efficient photocatalysts.

Surface plasmon resonance (SPR) has been utilized in many fields, such as surface-enhanced Raman spectroscopy (SERS) and solar energy conversion. Here we developed an Au@CdS core-shell nanostructure, a bifunctional nanoparticle, used as an efficient catalyst for SPR enhanced photocatalytic degradation, and as a substrate for in situ SERS detection of methylene blue (MB) and p-nitrophenol (pNTP). With integration of an Au nanoparticle into a CdS shell, the degradation process was significantly accelerated under 500 nm long-pass (λ > 500 nm) visible light irradiation, which was caused by the injection of hot electrons. Moreover, a highly uniform, monolayer film of Au@CdS nanoparticles (NPs) has been prepared and used as both a SERS substrate and catalyst. The decomposition of MB molecules and nitrogen coupling reaction of pNTP were observed during the 638 nm laser illumination. We demonstrate that a plasmonic core-semiconductor shell nanocomposite can be a promising material for photocatalysis and in situ SERS study.

Near-infrared photodetectors (NIRPDs) have attracted great attention because of their wide range of applications in many fields. Herein, a novel self-driven NIRPD at the wavelength of 980 nm is reported based on the graphene/GaAs heterostructure. Extraordinarily, its sensitivity to light illumination (980 nm) is far beyond the absorption limitation of GaAs (874 nm). This means that the photocurrent originates from the separation of photo-induced carriers in graphene, which is caused by the vertically built-in electric field formed through the high quality van der Waals contact between graphene and GaAs. Moreover, after introducing NaYF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs) onto the graphene/GaAs heterojunction, the responsivity increases to be as superior as 5.97 mA W-1 and the corresponding detectivity is 1.1 × 1011 cm Hz0.5 W-1 under self-driven conditions. This dramatic improvement is mainly ascribed to the radiative energy transfer from UCNPs to the graphene/GaAs heterostructure. The high-quality and self-driven UCNPs/graphene/GaAs heterostructure NIRPD holds significant potential for practical application in low-consumption and large-scale optoelectronic devices.

Photocatalytic water splitting is an ideal way of generating hydrogen, a renewable energy source, from solar energy that would help solve environmental problems. However, current photocatalysts are far from meeting performance requirements for commercial applications. Recently, increasing attention has been paid to surface plasmon resonance (SPR) enhanced photocatalysis using plasmonic nanoparticles (NPs) because of their superior solar energy harvesting capabilities in the visible and near-infrared spectral region. Herein, based on the common CdS photocatalyst, a series of core−shell plasmonic photocatalysts with different core types and shell layer thicknesses were constructed. By combining experimental results and finite element method (FEM), the near-field enhancement mechanism and plasmoninduced resonance energy transfer mechanism was derived. To further improve the energy conversion efficiency, a core− shell−satellite-type plasmonic nanocomposite photocatalyst, Ag@SiO 2 @CdS-Au, was designed and constructed. Because of hot electron injection and plasmonic coupling effects, the light absorption of the photocatalyst was effectively expanded, which significantly improved the catalytic performance. Compared with traditional CdS, the photocatalytic performance of the plasmonic nanocomposite photocatalyst was improved by more than 200 times. This work deepens the understanding of the mechanisms in SPR enhanced photocatalysis and provides an effective strategy for designing plasmonic photocatalysts.

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