Nanometer electrodes

NADH, 121, 122, 180 Nafion coating, 118, 123, 124, 126 Nanometer electrodes, 116, 128 Nernst equation, 3, 15, 80 Nernstian behavior, 143 Nernst Planck equation, 5 Neuronal sensors, 188 Neurotransmitters, 40, 116, 124 Neutral carrier electrodes, 154 Nickel, 123... 

Highly efficient hydrogen generation via water electrolysis using nanometal electrodes, September 2006, Energy Research Laboratory, QuantumSphere Inc., Santa Ana, CA. 

A value of Rqb for an SEI lOnm thick can be estimated from its values for CPE and CSE by assuming that these solid electrolytes consist of nanometer-sized particles. Thus the expected value for / GB at 30 °C for a lOnm SEI is in the range 10-lOOQcm2, i.e., it cannot be neglected. In some cases it may be larger than the ionic (bulk) resistance of the SEI. This calculation leads us to the conclusion that 7 GB and CGB must be included in the equivalent circuits of the SEI, for both metallic lithium and for LixC6 electrodes. The equivalent circuit for a mosaic-type... 

Electrochemistry is the basis of many important and modem applications and scientific developments such as nanoscale machining (fabrication of miniature devices with three dimensional control in the nanometer scale), electrochemistry at the atomic scale, scanning tunneling microscopy, transformation of energy in biological cells, selective electrodes for the determination of ions, and new kinds of electrochemical cells, batteries and fuel cells. 

Differences in behavior between polycrystalline and single-crystal CdSe electrodes in polysulfide PEC involving the short- and long-term changes in photovoltage and photocurrents have been discussed by Cahen et al. [88], on the basis of XPS studies, which verified the occurrence of S/Se substitution in these electrodes when immersed in polysulfide solution, especially under illumination. The presence of a thin (several nanometers) layer of CdS on top of the CdSe was shown to influence... 

Another convenient way to disperse platinum-based electrocatalysts is to use electron-conducting polymers, such as polyaniline (PAni) or polypyrrole (PPy), which play the role of a three-dimensional electrode.In such a way very dispersed electrocatalysts are obtained, with particle sizes on the order of a few nanometers, leading to a very high activity for the oxidation of methanol (Fig. 10). 

Campbell, S. D. and Hdber, A. C. (1999) Nanometer-scale probing of potential-dependent electrostatic forces, adhesion, and interfacial friction at the electrode/ electrolyte interface. Langmuir, 15, 891-899. 

Alivisatos and coworkers reported on the realization of an electrode structure scaled down to the level of a single Au nanocluster [24]. They combined optical lithography and angle evaporation techniques (see previous discussion of SET-device fabrication) to define a narrow gap of a few nanometers between two Au leads on a Si substrate. The Au leads were functionalized with hexane-1,6-dithiol, which binds linearly to the Au surface. 5.8 nm Au nanoclusters were immobilized from solution between the leads via the free dithiol end, which faces the solution. Slight current steps in the I U) characteristic at 77K were reflected by the resulting device (see Figure 8). By curve fitting to classical Coulomb blockade models, the resistances are 32 MQ and 2 G 2, respectively, and the junction... 

As described in the previous sections, a stable Pt skin of a few nanometers is formed on the Pt-Fe, Pt-Co, and Pt-Ni alloy surfaces after electrochemical stabilization. Figure 10.12 shows Arrhenius plots of kapp on the alloy electrodes at —0.525 V vs. E° in comparison with that of a pure Pt electrode. In the low temperature region (20-50 °C for Pt54Fe45, 20-60 °C for Pt6gCo32 and Ptg3Ni37), linear relationships between log kapp and 1 / Tare observed at all the electrodes, corresponding to the following Arrhenius equation ... 

Another type of model electrode uses multilayer electrolytic deposits, which attracted the interest of electrochemists long before physical methods for their structural characterization were introduced. These electrodes were usually characterized by their roughness factors rather than particle size, the former being of the order of 10 -10 (for original references, see the review [Petrii and Tsirhna, 2001]). Multilayer electrolytic deposits have very complex stmctures [Plyasova et al., 2006] consisting of nanometer-sized crystallites joined together via grain boundaries, and hence have very pecuhar electrocatalytic properties [Cherstiouk et al., 2008] they will not be considered further in this chapter. 

When a liquid-liquid interface is to be investigated using an electrode in the more dense phase, or for studies at the water-air interface, a submarine electrode can be deployed [18,19,34], depicted schematically in Fig. 3(b). In this case, the electrode is inverted in the cell, such that the tip points upwards, and an insulated connection is made through the solution. Metal electrodes down to the nanometer scale can also be fabricated by sealing an etched Pt or Pt-Ir wire in a suitable insulating material, leaving just the etched end exposed [35-37]. 

The development of hydrodynamic techniques which allow the direct measurement of interfacial fluxes and interfacial concentrations is likely to be a key trend of future work in this area. Suitable detectors for local interfacial or near-interfacial measurements include spectroscopic probes, such as total internal reflection fluorometry [88-90], surface second-harmonic generation [91], probe beam deflection [92], and spatially resolved UV-visible absorption spectroscopy [93]. Additionally, building on the ideas in MEMED, submicrometer or nanometer scale electrodes may prove to be relatively noninvasive probes of interfacial concentrations in other hydrodynamic systems. The construction and application of electrodes of this size is now becoming more widespread and general [94-96]. 

The best parameters of the I /I2 cell were achieved by using a non-aqueous electrolyte and the anatase electrode of nanometer-sized particles, sensitized with RuL ju - (NC)Ru(CN)(bpy)2)2. In 1991, B. O Regan and M. Gratzel described a cell attaining parameters competitive to commercial, solid-state photovoltaic devices. 

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