Wenjie Liang

Ultrafast Dynamics of Plasmon-Exciton Interaction of Ag Nanowire- Graphene Hybrids for Surface Catalytic Reactions

Using the ultrafast pump-probe transient absorption spectroscopy, the femtosecond-resolved plasmon-exciton interaction of graphene-Ag nanowire hybrids is experimentally investigated, in the VIS-NIR region. The plasmonic lifetime of Ag nanowire is about 150u2009±u20097 femtosecond (fs). For a single layer of graphene, the fast dynamic process at 275u2009±u200977u2009fs is due to the excitation of graphene excitons, and the slow process at 1.4u2009±u20090.3 picosecond (ps) is due to the plasmonic hot electron interaction with phonons of graphene. For the graphene-Ag nanowire hybrids, the time scale of the plasmon-induced hot electron transferring to graphene is 534u2009±u2009108u2009fs, and the metal plasmon enhanced graphene plasmon is about 3.2u2009±u20090.8u2009ps in the VIS region. The graphene-Ag nanowire hybrids can be used for plasmon-driven chemical reactions. This graphene-mediated surface-enhanced Raman scattering substrate significantly increases the probability and efficiency of surface catalytic reactions co-driven by graphene-Ag nanowire hybridization, in comparison with reactions individually driven by monolayer graphene or single Ag nanowire. This implies that the graphene-Ag nanowire hybrids can not only lead to a significant accumulation of high-density hot electrons, but also significantly increase the plasmon-to-electron conversion efficiency, due to strong plasmon-exciton coupling.

Optical, photonic and optoelectronic properties of graphene, h-BN and their hybrid materials

Abstract Because of the linear dispersion relation and the unique structure of graphene’s Dirac electrons, which can be tuned the ultra-wide band, this enables more applications in photonics, electronics and plasma optics. As a substrate, hexagonal boron nitride (h-BN) has an atomic level flat surface without dangling bonds, a weak doping effect and a response in the far ultraviolet area. So the graphene/h-BN heterostructure is very attractive due to its unique optical electronics characteristics. Graphene and h-BN which are stacked in different ways could open the band gap of graphene, and form a moiré pattern for graphene on h-BN and the superlattice in the Brillouin zone, which makes it possible to build photoelectric devices.

Exciton-plasmon coupling interactions: from principle to applications

Abstract The interaction of exciton-plasmon coupling and the conversion of exciton-plasmon-photon have been widely investigated experimentally and theoretically. In this review, we introduce the exciton-plasmon interaction from basic principle to applications. There are two kinds of exciton-plasmon coupling, which demonstrate different optical properties. The strong exciton-plasmon coupling results in two new mixed states of light and matter separated energetically by a Rabi splitting that exhibits a characteristic anticrossing behavior of the exciton-LSP energy tuning. Compared to strong coupling, such as surface-enhanced Raman scattering, surface plasmon (SP)-enhanced absorption, enhanced fluorescence, or fluorescence quenching, there is no perturbation between wave functions; the interaction here is called the weak coupling. SP resonance (SPR) arises from the collective oscillation induced by the electromagnetic field of light and can be used for investigating the interaction between light and matter beyond the diffraction limit. The study on the interaction between SPR and exaction has drawn wide attention since its discovery not only due to its contribution in deepening and broadening the understanding of SPR but also its contribution to its application in light-emitting diodes, solar cells, low threshold laser, biomedical detection, quantum information processing, and so on.

Surface Plasmon Resonance Sensors on Raman and Fluorescence Spectroscopy

The performance of chemical reactions has been enhanced immensely with surface plasmon resonance (SPR)-based sensors. In this review, the principle and application of SPR sensors are introduced and summarized thoroughly. We introduce the mechanism of the SPR sensors and present a thorough summary about the optical design, including the substrate and excitation modes of the surface plasmons. Additionally, the applications based on SPR sensors are described by the Raman and fluorescence spectroscopy in plasmon-driven surface catalytic reactions and the measurement of refractive index sensing, especially.

Exciton–plasmon hybrids for surface catalysis detected by SERS

Surface plasmons (SPs), in which the free electrons are collectively excited on the metal surface, have been successfully used in chemical analysis and signal detection. Generally, SPs possess two types of decay channels. SPs decay either nonradiatively via the generation of hot electrons or radiatively through re-emitted photons, which can trigger surface chemical reactions when the molecules are adsorbed on the surface of metal nanoparticles. An excitation light with a special wavelength is irradiated on the surface of the plasmonic nanostructure, the strong coupling interaction between electrons and light will then occur on this, and this is followed by the development of a series of unique properties. 2D materials have been a hot topic of research for more than a decade, since graphene was found in 2004. Recently, the combination of graphene with metal NPs has been shown to possess many supernormal advantages, such as high stability and catalytic activity, which have been successfully applied in plasmon-exciton co-driven chemical reactions.

Correction: Recent advances in surface plasmon-driven catalytic reactions

Correction for ‘Recent advances in surface plasmon-driven catalytic reactions’ by Xin Ren et al., RSC Adv., 2017, 7, 31189–31203.