Systems allowing label-free molecular detection are expected to have enormous impact on biochemical sciences. Research focuses on materials and technologies based on exploiting localized surface plasmon resonances in metallic nanostructures. The reason for this focused attention is their suitability for single molecule sensing, arising from intrinsically nanoscopic sensing volume, and the high sensitivity to the local environment. Here we propose an alternative route, which enables radically improved sensitivity compared torecently reported plasmon-based sensors. Such high sensitivity is achieved by exploiting the control of the phase of light in magnetoplasmonic nanoantennas. We demonstrate a manifold improvement of refractometric sensing figure-of-merit. Most remarkably, we show a raw surface sensitivity (i.e., without applying fitting procedures) of two orders of magnitude higher than the current values reported for nanoplasmonic sensors. Such sensitivity corresponds to a mass of ~0.8 ag per nanoantenna of polyamide-6.6 (n=1.51), which is representative for a large variety of polymers, peptides and proteins.

A single nanopore structure that embeds all components of an electrochemical storage device could bring about the ultimate miniaturization in energy storage. Self-alignment of electrodes within each nanopore may enable closer and more controlled spacing between electrodes than in state-of-art batteries. Such an 'all-in-one' nanopore battery array would also present an alternative to interdigitated electrode structures that employ complex three-dimensional geometries with greater spatial heterogeneity. Here, we report a battery composed of an array of nanobatteries connected in parallel, each composed of an anode, a cathode and a liquid electrolyte confined within the nanopores of anodic aluminium oxide, as an all-in-one nanosize device. Each nanoelectrode includes an outer Ru nanotube current collector and an inner nanotube of V₂O₅ storage material, forming a symmetric full nanopore storage cell with anode and cathode separated by an electrolyte region. The V₂O₅ is prelithiated at one end to serve as the anode, with pristine V₂O₅ at the other end serving as the cathode, forming a battery that is asymmetrically cycled between 0.2 V and 1.8 V. The capacity retention of this full cell (relative to 1 C values) is 95% at 5 C and 46% at 150 C, with a 1,000-cycle life. From a fundamental point of view, our all-in-one nanopore battery array unveils an electrochemical regime in which ion insertion and surface charge mechanisms for energy storage become indistinguishable, and offers a testbed for studying ion transport limits in dense nanostructured electrode arrays.

ABSTRACT:Several active areas of research in novel energy storage technologies, including threedimensional solid state batteries and passivation coatings for reactive battery electrode components, require conformal solid state electrolytes. We describe an atomic layer deposition (ALD) process for a member of the lithium phosphorus oxynitride (LiPON) family, which is employed as a thin film lithium-conducting solid electrolyte. The reaction between lithium tertbutoxide (LiO t Bu) and diethyl phosphoramidate (DEPA) produces conformal, ionically conductive thin films with a stoichiometry close to Li 2 PO 2 N between 250 and 300C. The P/N ratio of the films is always 1, indicative of a particular polymorph of LiPON which closely resembles a polyphosphazene. Films grown at 300C have an ionic conductivity of 6.51 (±0.36) × 10 −7 S/cm at 35C, and are functionally electrochemically stable in the window from 0 to 5.3V vs. Li/Li+. We demonstrate the viability of the ALD-grown electrolyte by integrating it into full solid state batteries, including thin film devices using LiCoO 2 as the cathode and Si as the anode operating at up to 1 mA/cm 2 . The high quality of the ALD growth process allows pinhole-free deposition even on rough crystalline surfaces, and we demonstrate the fabrication and operation of thin film batteries with the thinnest (<100nm) solid state electrolytes yet reported. Finally, we show an additional application of the moderate-temperature ALD process by demonstrating a flexible solid state battery fabricated on a polymer substrate.3

A new atomic layer deposition (ALD) process for V 2 O 5 using ozone (O 3 ) as oxidant has been developed that resulted in crystalline V 2 O 5 thin films which are single-phase and orthorhombic on various substrates (silicon, Au-coated stainless steel, and anodic aluminum oxide (AAO)) without any thermal post-treatment. Within a fairly narrow temperature window (170−185°C), this low temperature process yields a growth rate of ∼0.27 Å/cycle on Si. It presents good uniformity on planar substrates. Excellent conformality enables deposition into high aspect ratio (AR) nanopores (AR > 100), as needed for fabrication of three-dimensional (3D) nanostructures for next generation electrochemical energy storage devices. V 2 O 5 films obtained using O 3 -based ALD showed superior electrochemical performance in lithium cells, with initial specific discharge capacity of 142 mAh/g in the potential range of 2.6−4.0 V, as well as excellent rate capability and cycling stability. These benefits are attributed primarily to the crystallinity of the material and to fast transport through the thin active storage layers used. KEYWORDS: atomic layer deposition, vanadium oxide, ozone, electrochemical energy storage ■ INTRODUCTIONElectrical energy storage is a key challenge for effective use of conventional and renewable energy sources. Applications include electric vehicles, residential energy systems based on renewables, management of distributed and grid level large scale power systems, and portable electronic devices. 1,2 Electrochemical devices for reversible charge storage, both Li ion batteries and supercapacitors, are needed with high power and high energy density. Three-dimensional (3D) nanostructures offer large surface area, enabling active storage material in the nanostructures to be spatially close to electrolyte, reducing diffusion time for Li transport to fully utilize the active material and thus achieving higher power. However, high density nanostructure arrays, aimed at maintaining high gravimetric and volumetric energy density, require materials synthesis methods capable of conformally coating nanostructures in high aspect ratio (AR) 3D geometries. 3−5 Conformal thin film coating methods are required to achieve mechanically stable, binder-free, and high surface area electrodes. 6,7 Atomic layer deposition (ALD) is a unique thin-film deposition technique which exploits self-limited reactions, leading to monolayer thickness control and unprecedented uniformity and conformality in even the most stringent high AR nanostructures. It is therefore a very promising technique for fabrication of nanoscale heterostructured 3D energy storage devices as we have shown in previous work. 7,8 Cathode materials typically limit the energy density of electrochemical storage devices since they have much lower specific capacities compared with anode materials. 2 Among well-known cathode materials, V 2 O 5 offers relatively high specific capacity (147 mAh/g at 2.6−4.0 V; 294 mAh/g at 2.0− 4.0 V), fast lithiation, and better safety, which has...

Light scattering from an array of aligned multiwall carbon nanotubes (MWCNTs) has previously been investigated, [1,2] and shown to be consistent with that from an array of antennae. Two basic antenna effects have been demonstrated: 1) the polarization effect, which suppresses the response of an antenna when the electric field of the incoming radiation is polarized perpendicular to the dipole antenna axis, and 2) the antenna-length effect, which maximizes the antenna response when the antenna length is a multiple of the radiation half wavelength in the medium surrounding the antenna. In these previous experiments a random nanotube array was chosen to eliminate the intertube diffraction effects. In this communication, we provide compelling evidence of the antenna action of an MWCNT, by demonstrating that its directional radiation characteristics are in an excellent and quantitative agreement with conventional radio antenna theory and simulations.According to conventional radio antenna theory, [3][4][5][6] a simple "thin" wire antenna (a metallic rod of diameter d and length l >> d) maximizes its response to a wavelength k when l = mk/2, where m is a positive integer. Thus, an antenna acts as a resonator of the external electromagnetic radiation. An antenna is a complex boundary value problem; it is a resonator for both the external fields, and the currents at the antenna surface. In a long radiating antenna, a periodic pattern of current distribution is excited along the antenna, synchronized with the pattern of fields outside. The current pattern consists of segments, with the current direction alternating from segment to segment. Thus, a long antenna can be viewed as an antenna array consisting of smaller, coherently driven antennae (segments) in series. Therefore, the resulting radiation pattern, as a function of the angle with respect to the antenna axis, consists of lobes of constructive interference, separated by radiation minima due to destructive interference. Consider a simple antenna as shown in Figure 1a. The radiation pattern produced by this antenna is rotationally symmetric about the z axis. For a center-fed antenna, or one excited by an external wave propagating perpendicular to the antenna axis (i.e., with the glancing angle h i = 90°), the pattern is also symmetric with respect to the x-y plane. For an antenna excited by an incoming wave propagating at an angle (h i < 90°), the relative strengths of the radiation lobes are expected to shift towards the specular direction. This follows from a qualitative argument based on the single-photon scattering picture, and conservation laws for scattered photons from an antenna. Since such scattering is elastic, the energy of each scattering photon បx (where ប is the reduced Planck constant and x is the angular frequency) and its total momentum បk = បk i  = បk s  (where k is the wave number, k i is the incident wave vector, and k s is the scattered wave vector) must be conserved. Due to the cylindrical symmetry, បK, the length of the momentum vector compo...