Lignin-based porous junction for silver-silver chloride reference electrodes

Carbonized lignin powder was used as a salt bridge for a silver-silver chloride reference electrode. This easy-to-prepare reference electrode exhibited excellent stability in saturated potassium chloride solution. In addition, the electrochemical impedance spectra showed that the prepared reference electrode is stable in acidic, neutral, and basic aqueous solutions (pH 1 - 12) and has similar impedances to its glass frit equivalent

Anodic HfO2 crossbar arrays for hydroxide-based memristive sensing in liquids

The development of miniaturized and portable sensing devices is crucial to meeting the high processing capacity demands of contemporary computing systems. Hence, the conceptualization of memristive sensors for hydroxide-containing liquids is proposed in this study. Metal-insulator-metal (MIM) structures were formed on electrochemically anodized Hf thin films with Pt patterned as top electrodes. These MIM memristive structures were integrated into a crossbar array, allowing the investigation of a high number of potential memristor sensors. The MIM structures have demonstrated sensing possibilities in the detection of the hydroxyl ion in D-glucose, used as a standard solution. The sensing method was based on the resistive state ratio extracted from I-U sweeps measurements. Analytical characterization of the memristor sensor was done based on the resistive state ratio in relation to different concentrations of a standard solution drop cast directly on the surface of the device. Linearity was found for D-glucose concentrations ranging from 10 mM to 80 mM with a reasonable corresponding correlation factor (R2=0.96809). Additionally, D-glucose incorporation in anodic oxide was studied by XPS to investigate its effect on conductive filaments formation. A carbon bonded by a single covalent bond to oxygen (O-C-O) was detected, confirming the proposed sensing mechanism defined by the glucose penetrating the oxide/electrode interface

Nanomechanics of Single Crystalline Tungsten Nanowires

Single crystalline tungsten nanowires were prepared from directionally solidified NiAl-W alloys by a chemical release from the resulting binary phase material. Electron back scatter diffraction (EBSD) proves that they are single crystals having identical crystallographic orientation. Mechanical investigations such as bending tests, lateral force measurements, and mechanical resonance measurements were performed on 100–300 nm diameter wires. The wires could be either directly employed using micro tweezers, as a singly clamped nanowire or in a doubly clamped nanobridge. The mechanical tests exhibit a surprisingly high flexibility for such a brittle material resulting from the small dimensions. Force displacement measurements on singly clamped W nanowires by an AFM measurement allowed the determination of a Young's modulus of 332 GPa very close to the bulk value of 355 GPa. Doubly clamped W nanowires were employed as resonant oscillating nanowires in a magnetomotively driven resonator running at 117 kHz. The Young's modulus determined from this setup was found to be higher 450 GPa which is likely to be an artefact resulting from the shift of the resonance frequency by an additional mass loading

Trapping of transient processes in aluminium oxide thin films in a voltage pulse experiment

An experimental setup is presented that allows the trapping of transient states in potentiostatic and potentiodynamic experiments. The setup is suitable for electrochemical experiments as well as for dielectric investigations. The system stops an experiment by triggering at a predefined current level after a minimum time of the voltage pulse. The advantage of this device is demonstrated by means of a voltage pulse annealing procedure for a metal–insulator–metal (MIM) contact with an anodically prepared aluminium oxide film as insulator. The setup significantly increases the stability against a breakdown of the anodic oxide film. Keywords: Current transients, Dielectric films, Aluminium, Tunnelling, Electrochemistry, MI

Electrocatalysis on gold nanostructures: Is the {1 1 0} facet more active than the {1 1 1} facet?

The anisotropic electrocatalytic properties of gold nanobelts and nanoplates enclosed by either {1 1 0} or {1 1 1} facets were studied. Different strategies were used to synthesize these materials. It was found that the {1 1 0} surface of gold does not necessarily show a higher electrocatalytic activity than the {1 1 1} surface. The {1 1 0} surface of gold is more active than the {1 1 1} surface for glucose oxidation in both, neutral and alkaline media. However, for methanol oxidation in alkaline solution, the {1 1 0} surface shows a lower activity than the {1 1 1} surface, which is contrary to the general belief that {1 1 0} facet is the most active surface among the three basal planes. The possible mechanisms are discussed. Keywords: Anisotropic, Nanobelts, Nanoplates, Glucose, Methano