The synthesis of large lattice mismatch metal-semiconductor core-shell hetero-nanostructures remains challenging, and thus the corresponding optical properties are seldom discussed. Here, we report the gold-nanorodseeded growth of Au-CdS core-shell hetero-nanorods by employing Ag 2 S as an interim layer that favors CdS shell formation through a cation-exchange process, and the subsequent CdS growth, which can form complete coreshell structures with controllable shell thickness. Exciton-plasmon interactions observed in the Au-CdS nanorods induce shell thickness-tailored and red-shifted longitudinal surface plasmon resonance and quenched CdS luminescence under ultraviolet light excitation. Furthermore, the Au-CdS nanorods demonstrate an enhanced and plasmon-governed two-photon luminescence under near-infrared pulsed laser excitation. The approach has potential for the preparation of other metal-semiconductor hetero-nanomaterials with complete core-shell structures, and these Au-CdS nanorods may open up intriguing new possibilities at the interface of optics and electronics.

Poly(vinylpyrrolidone)-encapsulated Bi2 Se3 nanosheets with a thickness of 1.7 nm and diameter of 31.4 nm are prepared by a solution method. Possessing an extinction coefficient of 11.5 L g(-1) cm(-1) at 808 nm, the ultrathin Bi2 Se3 nanosheets boast a high photothermal conversion efficiency of 34.6% and excellent photoacoustic performance. After systemic administration, the Bi2 Se3 nanosheets with the proper size and surface properties accumulate passively in tumors enabling efficient photoacoustic imaging of the entire tumors to facilitate photothermal cancer therapy. In vivo biodistribution studies reveal that they are expelled from the body efficiently after 30 d. The ultrathin Bi2 Se3 nanosheets have large clinical potential as metabolizable near-infrared-triggered theranostic agents.

The design of new functional materials with excellent hydrogen production activity under visible‐light irradiation has critical significance for solving the energy crisis. A well‐controlled synthesis strategy is developed to prepare an Au–Pt–CdS hetero‐nanostructure, in which each component of Au, Pt, and CdS has direct contact with the other two materials; Pt is on the tips and a CdS layer along the sides of an Au nanotriangle (NT), which exhibits excellent photocatalytic activity for hydrogen production under light irradiation (λ > 420 nm). The sequential growth and surfactant‐dependent deposition produce the three‐component Au–Pt–CdS hybrids with the Au NT acting as core while Pt and CdS serve as a co‐shell. Due to the presence of the Au NT cores, the Au–Pt–CdS nanostructures possess highly enhanced light‐harvesting and strong local‐electric‐field enhancement. Moreover, the intimate and multi‐interface contact generates multiple electron‐transfer pathways (Au to CdS, CdS to Pt and Au to Pt) which guide photoexcited electrons to the co‐catalyst Pt for an efficient hydrogen reduction reaction. By evaluating the hydrogen production rate when aqueous Na2SO3–Na2S solution is used as sacrificial agent, the Au–Pt–CdS hybrid exhibits excellent photocatalytic activity that is about 2.5 and 1.4 times larger than those of CdS/Pt and Au@CdS/Pt, respectively.

A novel strategy is proposed to directly synthesize water-soluble hexagonal NaYF 4 nanorods by doping rare-earth ions with large ionic radius (such as La 3+ ), and the dopantcontrolled growth mechanism is studied. Based on the doping effect, we fabricated water-soluble hexagonal NaYF 4 :(Yb,Er)/La and NaYF 4 :(Yb,Er)/Ce nanorods, which exhibited much brighter upconversion fluorescence than the corresponding cubic forms. The sizes of the nanorods can be adjusted over a broad range by changing the dopant concentration and reaction time. Furthermore, we successfully demonstrated a novel depth-sensitive multicolor bioimaging for in vivo use by employing the as-synthesized NaYF 4 :(Yb,Er)/La nanorods as probes.

We theoretically investigated optical third-order nonlinearity of a coherently coupled exciton-plasmon hybrid system under a strong control field with a weak probe field. The analytic formulas of exciton population and effective third-order optical susceptibility of the hybrid of a metal nanoparticle (MNP) and a semiconductor quantum dot (SQD) were deduced. The bistable exciton population and the induced bistable nonlinear absorption and refraction response were revealed. The bistability region can be tuned by adjusting the size of metal nanoparticle, interparticle distance and intensity of control field. Our results have perspective applications in optical information processing based on resonant coupling of exciton-plasmon.

NdF3/SiO2 nanoparticles demonstrate highly efficient fluorescence due to successful suppressions of concentration quenching and surface quenching. More interestingly, their excitation and emission peaks with large frequency separation are both in the “near‐infrared optical window” of biotissues. In living animal studies, the detecting depth can reach 1 cm by using a small dose of such nanomaterials.

We theoretically investigate the plasmon coupling in metallic nanorod dimers. A pronounced dip is found in the extinction spectrum due to plasmonic Fano resonance, which is induced by destructive interference between the bright dipole plasmon of a short nanorod and the dark quadrupole plasmon of a long nanorod. This Fano interference can also be explained as the coupling between the bright and dark modes both supported by the whole dimer. The Fano resonance can be tuned by adjusting the spatial or spectral separation between two nanorods in the dimer.

Localized surface plasmon resonances (LSPRs) of metal nanostructures are highly related to the shape, which could greatly enhance the light−matter interaction at nanoscale. Here, we investigate the LSPRs of gold nanostars corresponding to the unique morphology and demonstrate surface-enhanced Raman scattering (SERS) activities and nonlinear refraction properties of two typical structures. By adjusting the synthesis condition, the main plasmon resonance could be tuned from 557 to 760 nm. The plasmon modes and intense field enhancement near the sharp tips are revealed by finite-difference timed-domain (FDTD) simulations. The nonlinear refractive index |γ| reaches to the maximum value when the excitation wavelength is resonant to the LSPRs wavelength. The maximum value of |γ| for long-branched nanostars (λ SP = 706 nm) is 5.843 × 10 −4 cm 2 / GW, which is about 1.5 times larger than that of spherical-like nanostars with λ SP = 563 nm. The SERS activity of long-branched nanostars is about 15 times larger than that of spherical-like gold nanostars.