Copper gold crystallites

Fig. 5. Gold polycrystaUine surface with copper-gold alloy crystallites grown by performing cycles of copper electrodeposition and dissolution, (a) After first cycle E = 400 mV, Ex = 442 mV, d = 44 nm, Ii= 1.8 nA. (b) After second cycle. In-situ images d = 42 nm, /( = 2.1 nA, Electrolyte 0.001 M CUSO4 and 0.05 M H2SO4 in Millipore water, E = 400 mV, Ex = 442 mV.

As observed by in-situ STM the metal is also dissolved before the maximum current is reached in the voltammogram en the potentials are swept from cathodic to anodic values [11]. Figure 4(b) shows the first stages of copper dissolution (vs. Cu VCu) where copper gradually enters the ionic state finm the top layers. When copper dissolves, a small fraction remains and alloys with the gold polycrystalline surface to from nanometer-scale crystallites (Fig. 5(a, b)). In Figure 5(a) the alloy nuclei form... 

Fig.7. In-situ STM images of copper potentiostatic pulse plating on gold. Electrolyte 0.001 M CUSO4 and 0.05 M H2SO4 in Millipore water, (a) Clean surface, d = 9 mn. (b) Ten pulses of 0/-100 mV, each 500 ms duration (stripes), d— 44 nm. (c)Copper crystallites created by the process, E=0 mV, Et = 42 mV, d = 29 mn. It = 4.2 nA.

Tin dioxide, an n-type semiconductor with a wide bandgap (3.6 eV at 300 K), has been widely studied as a sensor, a (photo)electrode material and in oxidation reactions for depollution. The performance of tin(iv) oxide is closely linked to structural features, such as nanosized crystallites, surface-to-volume ratio and surface electronic properties. The incentive for carbon-dioxide transformation into value-added products led to examination of the electroreduction of carbon dioxide at different cathodes. It has been recognised that the faradic yield and selectivity to carbon monoxide, methane, methanol, and formic acid rely upon the nature of the cathode and pH. ° Tin(iv) oxide, as cathode, was found to be selective in formate formation at pH = 10.2 with a faradic yield of 67%, whereas copper is selective for methane and ethene, and gold and silver for carbon monoxide. Nano-tin(iv) oxide has been shown to be active and selective in the carboigrlation of methanol to dimethyl carbonate at 150 °C and 20 MPa pressure. The catalyst was recyclable and its activity and selectivity compare with that of soluble organotins (see Section 21.5). 

EAM-potentials from Ref. [11] were used for gold potentials from Ref [12] were used for copper and potentials from Ref [13] - for nickel. The chosen EAM-potentials are uniform over the wide range of temperature and density they provide adequate elastic and energy characteristics of gold, copper and nickel, reasonable thermal extension and temperature of melting of model crystallites. 

Dendrimers have been studied by low dose electron microscopy, using samples prepared by deposition of a dilute solution of the PAM family of molecules (based on a cyclic phenyl-acetylene backbone) in toluene onto amorphous carbon coated mica sheets [25]. Once the solvent is dried, the carbon film and crystallite layer were floated off the mica substrate and collected on copper grids gold was evaporated on the samples as a calibration standard for electron microscopy. 

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