Ferroic-order parameters are useful as state variables in non-volatile information storage media because they show a hysteretic dependence on their electric or magnetic field. Coupling ferroics with quantum-mechanical tunnelling allows a simple and fast readout of the stored information through the influence of ferroic orders on the tunnel current. For example, data in magnetic random-access memories are stored in the relative alignment of two ferromagnetic electrodes separated by a non-magnetic tunnel barrier, and data readout is accomplished by a tunnel current measurement. However, such devices based on tunnel magnetoresistance typically exhibit OFF/ON ratios of less than 4, and require high powers for write operations (>1 × 10(6) A cm(-2)). Here, we report non-volatile memories with OFF/ON ratios as high as 100 and write powers as low as ∼1 × 10(4) A cm(-2) at room temperature by storing data in the electric polarization direction of a ferroelectric tunnel barrier. The junctions show large, stable, reproducible and reliable tunnel electroresistance, with resistance switching occurring at the coercive voltage of ferroelectric switching. These ferroelectric devices emerge as an alternative to other resistive memories, and have the advantage of not being based on voltage-induced migration of matter at the nanoscale, but on a purely electronic mechanism.

We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by square-wave anodic stripping voltammetry (SWASV) using a bismuth nanoparticle modified boron doped diamond (Bi-BDD) electrode. Bi deposition was performed in situ with the analytes, from a solution of 0.1 mM Bi(NO3)3 in 0.1 M HClO4 (pH 1.2), and gave detection limits of 1.9 µg L-1 and 2.3 µg L-1 for Pb(II) and Cd(II) respectively. Pb2+ and Cd2+ could not be detected simultaneously at a bare BDD electrode, whilst on a bulk Bi macro electrode (BiBE) the limits of detection for the simultaneous determination of Pb2+ and Cd2+ were ca. ten times higher

We report the fabrication of a Ni nanoparticle modified BDD electrode and its application in the electrocatalysis of primary alcohol electrooxidation. Modification was achieved via electrodeposition from Ni(NO 3 ) 2 dissolved in sodium acetate solution (pH 5). Characterization of the Ni-modified BDD (Ni-BDD) was performed using ex situ atomic force microscopy (AFM) and high resolution scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Large nanoparticles of nickel were observed on the BDD surface ranging 5 to 690 nm in height and 0.18 mm À3 in volume, and an average number density of ca. 13 Â 10 6 nanoparticles cm À2was determined. The large range of sizes suggests progressive rather than instantaneous nucleation and growth. Electrocatalysis of ethanol and glycerol, was conducted in an alkaline medium using an unmodified BDD, Ni-BDD and a bulk Ni macro electrode. The Ni-BDD electrode gave the better electrocatalytic performance, with glycerol showing the greatest sensitivity. Linear calibration plots were obtained for the ethanol and glycerol additions over concentration ranges of 2.8 -28.0 mM and 23 -230 mM respectively. This gave an ethanol limit of detection of 1.7 mM and sensitivity of 0.31 mA/M, and the glycerol a limit of detection of 10.3 mM with a sensitivity of 35 mA/M.

We report a $60% increase in open circuit voltage (V oc ) and power conversion efficiency in a chloroaluminium phthalocyanine (ClAlPc)/fullerene (C 60 ) planar heterojunction photovoltaic device after insertion of a MoO 3 hole-extracting layer at the interface between the indium tin oxide (ITO) electrode and the ClAlPc donor layer, with an associated improvement in device stability. A similar improvement was observed in heterojunction devices based on mixed ClAlPc/C 60 layers. We propose that the improvements in device performance are due to the pinning of the ITO Fermi level to the valance band of the MoO 3 interlayer, where the latter is closely aligned with the highest occupied molecular orbital of ClAlPc.

Owing to the considerable current interest in replacing fossil fuels with solar radiation as a clean, renewable, and secure energy source, light-driven electron transport in natural photosynthetic systems offers a valuable blueprint for conversion of sunlight to useful energy forms. In particular, intracytoplasmic membrane vesicles (chromatophores) from the purple bacterium Rhodospirillum rubrum provide a fully functional and robust photosynthetic apparatus, ideal for biophysical investigations of energy transduction and incorporation into biohybrid photoelectrochemical devices. These vesicular organelles, which arise by invagination of the cytoplasmic membrane, are the sites of the photochemical reaction centers and the light harvesting 1 (LH1) complex. The LH1 protein is responsible for collecting visible and near-IR radiant energy and funneling these excitations to the reaction center for conversion into a transmembrane charge separation. Here, we have investigated the morphology, fluorescence kinetics and photocurrent generation of chromatophores from Rsp. rubrum deposited directly onto gold surfaces in the absence of chemical surface modifications. Atomic force microscopy showed a significant coverage of the gold electrode surface by Rsp. rubrum chromatophores. By in situ fluorescence induction/relaxation measurements, a high retention of the quantum yield of photochemistry was demonstrated in the photoactive films. Chronoamperometric measurements showed that the assembled bioelectrodes were capable of generating sustained photocurrent under white light illumination at 220 mW/cm(2) with a maximum current of 1.5 μA/cm(2), which slowly declines in about 1 week. This study demonstrates the possibility of photoelectrochemical control of robust chromatophore preparations from Rsp. rubrum that paves the way for future incorporation into functional solar cells.