Carbon anodes, nanostructurated

The electrocatalytic activity of the nanostructured Au and AuPt catalysts for MOR reaction is also investigated. The CV curve of Au/C catalysts for methanol oxidation (0.5 M) in alkaline electrolyte (0.5 M KOH) showed an increase in the anodic current at 0.30 V which indicating the oxidation of methanol by the Au catalyst. In terms of peak potentials, the catalytic activity is comparable with those observed for Au nanoparticles directly assembled on GC electrode after electrochemical activation.We note however that measurement of the carbon-supported gold nanoparticle catalyst did not reveal any significant electrocatalytic activity for MOR in acidic electrolyte. The... 

In this chapter, two carbon-supported PtSn catalysts with core-shell nanostructure were designed and prepared to explore the effect of the nanostructure of PtSn nanoparticles on the performance of ethanol electro-oxidation. The physical (XRD, TEM, EDX, XPS) characterization was carried out to clarify the microstructure, the composition, and the chemical environment of nanoparticles. The electrochemical characterization, including cyclic voltammetry, chronoamperometry, of the two PtSn/C catalysts was conducted to characterize the electrochemical activities to ethanol oxidation. Finally, the performances of DEFCs with PtSn/C anode catalysts were tested. The microstmc-ture and composition of PtSn catalysts were correlated with their performance for ethanol electrooxidation. 

In addition, materials prepared by anodization permit the growth of the oxide nanostructured film over a conductive substrate (Ti foil), an important aspect for preparation of robust electrodes. As discussed later, electrical contact with the conductive substrate could be further improved using carbon nano tubes. 

Recently, carbon nanotubes, an important class of one-dimensional nanostructures, have been fabricated within the pores of anodic alumina via CVD (Davydov et al, 1999 Li et al, 1999 Iwasaki et al., 1999 Suh et al, 1999). A small amount of metal (e.g., Co) is first electrochemically deposited on the bottom of the pores as a catalyst for the carbon nanotube growth, and the template is heated to 700 to 800°C in a flowing gas mixture of N2 and acetylene or ethylene. The hydrocarbon molecules are then pyrolyzed to... 

Nanostructured aluminum [74—78], iron [74] and aluminum-manganese alloys [74] have been prepared from a Lewis acid A1Q3/[BMIM]Q mixture (65 mol% AICI3, 35 mol% [BMIMJC1) whereas palladium alloys have been deposited from a Lewis basic system (45 mol% Aid , 55 mol% [BMIMJC1). The electrochemical cell and all parts which are in contact with the electrolyte have to be built from inert materials. As cathode material glassy carbon can be used. A constant ion concentration in the electrolyte can be realized by the use of a sacrificial anode consisting of the... 

A relatively high reversible capacity (372mAh/g, i.e., one lithium for six carbon atoms in standard conditions) at a potential close to metallic lithium and a moderate irreversible capacity can be obtained with graphite-based anodes. A higher degree of reversible lithium insertion than in graphite, but also an important irreversible capacity, is observed with various kinds of nanostructured carbons. Therefore, an intensive research effort is focused on the optimization of the anodic carbon materials, with the objectives to enhance the reversible capacity and to reduce as much as possible the irreversible capacity and hysteresis, which are often important drawbacks of these materials. The next section will discuss the correlations between the electrochemical performance of nanostructured carbons and their nanotexture/structure and surface functionality. Taking into account the key parameters that control the electrochemical properties, some optimizations proposed in literature will be presented. 

The fact that ALD is based on a self-terminating gas-solid reaction yielding excellent deposition conformality aliows to coat high aspect ratio nanostructures, including colloidal arrays, anodized alumina and track etched poly(carbonate) membranes [19, 20]. 

Figure 7.2 Representative 2-D nanostructured surfaces for bone-specific drug delivery systems, (a) Selenium nanoparticle-coated titanium surface, scale bar=500nm (reprinted from Ref. [54] with permission) (b) nanotubular anodized titanium surface, scale bar= 100 nm (reprinted from Ref. [26] with permission) (c) carbon nanotubes (CNT) grown out of anodized nanotubular titanium surface, scale bar=200nm (reprinted from Ref. [26] with permission) and (d) nanocrystaUine diamond surface, scale bar=200nm.

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