The conversion of electromagnetic energy into heat by nanoparticles has the potential to be a powerful, non-invasive technique for biotechnology applications such as drug release, disease treatment and remote control of single cell functions, but poor conversion efficiencies have hindered practical applications so far. In this Letter, we demonstrate a significant increase in the efficiency of magnetic thermal induction by nanoparticles. We take advantage of the exchange coupling between a magnetically hard core and magnetically soft shell to tune the magnetic properties of the nanoparticle and maximize the specific loss power, which is a gauge of the conversion efficiency. The optimized core-shell magnetic nanoparticles have specific loss power values that are an order of magnitude larger than conventional iron-oxide nanoparticles. We also perform an antitumour study in mice, and find that the therapeutic efficacy of these nanoparticles is superior to that of a common anticancer drug.

Nanostructures with chiral geometries exhibit strong polarization rotation. However, achieving reversible modulation of chirality and polarization rotation in device-friendly solid-state films is difficult for rigid materials. Here, we describe nanocomposites, made by conformally coating twisted elastic substrates with films assembled layer-by-layer from plasmonic nanocolloids, whose nanoscale geometry and rotatory optical activity can be reversibly reconfigured and cyclically modulated by macroscale stretching, with up to tenfold concomitant increases in ellipticity. We show that the chiroptical activity at 660 nm of gold nanoparticle composites is associated with circular extinction from linear effects. The polarization rotation at 550 nm originates from the chirality of nanoparticle chains with an S-like shape that exhibit a non-planar buckled geometry, with the handedness of the substrate's macroscale twist determining the handedness of the S-like chains. Chiroptical effects at the nexus of mechanics, excitonics and plasmonics open new operational principles for optical and optoelectronic devices from nanoparticles, carbon nanotubes and other nanoscale components.

Two-dimensional crystals, which possess a nanoscale dimension only in the c axis and have infinite length in the plane, have been emerging as important new materials owing to their unique properties and potential applications in areas ranging from electronics to catalysis. [1][2][3][4][5] In particular, recent developments of 2D nanosheet crystals such as stable graphene and transition-metal chalcogenides (TMCs) have sparked new discoveries in condensed-matter physics and electronics.[6] Further miniaturization of these 2D structures by lateral confinements can potentially bring not only the modulation of electron-transport phenomena [7] but also the enhancement of their 2D host capabilities which arise from the enlarged surface area and improved diffusion processes upon the intercalation of guest molecules.[8] However, synthetic routes for such laterally confined 2D crystals, especially for TMCs, have been challenging since they are unstable and immediately scroll up into closed structures such as quasi-0D onions or 1D tubes owing to increased peripheral dangling bonds. [9][10][11] Herein, we have developed an entirely new "shapetransformation" concept that proceeds by a rolling out of 1D tungsten oxide nanorods for the fabrication of laterally confined (less than 100 nm) 2D WS 2 nanosheet crystals. Here, a surfactant-assisted low-temperature (lower than 350 8C) solution process is also critical in stabilizing 2D nanosheet structures as opposed to conventional high-temperature (higher than 700 8C) gas-solid routes which yield only 0D or 1D structures. [12][13][14] Our 2D WS 2 nanosheet crystals are synthesized from tungsten oxide (W 18 O 49 ) nanorods [15,16] in the presence of carbon disulfide in hot hexadecylamine solution.Figure 1 a shows an overview of our shape-transformation scheme for the generation of 2D WS 2 nanosheet crystals from the tungsten oxide rods. The reaction between the carbon disulfide and hexadecylamine generates in situ hydrogen disulfide and hexadecylisothiocyanate via N-hexadecyldithiocarbamate as a transient species [Eq. (1); see also Figures S1 and S2 in the Supporting Information], and subsequent

An Si photoelectrode with a nanoporous Au thin film for highly selective and efficient photoelectrochemical (PEC) CO 2 reduction reaction (CO 2 RR) is presented. The nanoporous Au thin film is formed by electrochemical reduction of an anodized Au thin film. The electrochemical treatments of the Au thin film critically improve CO 2 reduction catalytic activity of Au catalysts and exhibit CO Faradaic efficiency of 96% at 480 mV of overpotential. To apply the electrochemical pretreatment of Au films for PEC CO 2 RR, a new Si photoelectrode design with mesh-type co-catalysts independently wired at the front and the back of the photoelectrode is demonstrated. Due to the superior CO 2 RR activity of the nanoporous Au mesh and high photovoltage from Si, the Si photoelectrode with the nanoporous Au thin film mesh shows conversion of CO 2 to CO with 91% Faradaic efficiency at positive potential than the CO 2 / CO equilibrium potential.

Regioselective chemical reactions and structural transformations of two-dimensional (2D) layered transition-metal chalcogenide (TMC) nanocrystals are described. Upon exposure of 2D TiS(2) nanodiscs to a chemical stimulus, such as Cu ion, selective chemical reaction begins to occur at the peripheral edges. This edge reaction is followed by ion diffusion, which is facilitated by interlayer nanochannels and leads to the formation of a heteroepitaxial TiS(2)-Cu(2)S intermediate. These processes eventually result in the generation of a single-crystalline, double-convex toroidal Cu(2)S nanostructure. Such 2D regioselective chemical reactions also take place when other ionic reactants are used. The observations made and chemical principles uncovered in this effort indicate that a general approach exists for building various toroidal nanocrystals of substances such as Ag(2)S, MnS, and CdS.