Ag, metallic

The existence of diamagnetic salts of AgF was first reported in 1957 (26), butHttle was known about their properties. In 1988 (27) it was claimed that AgF3 was prepared by a reaction of Ag metal and O2F2 iu CIF. Silver trifluoride [91899-63-7], AgF, has since been prepared (28) from anhydrous HF solutions of AgF 4 salts by addition of BF, PF, or AsF. ... 

Alkaline Fuel Cell. The electrolyte ia the alkaline fuel cell is concentrated (85 wt %) KOH ia fuel cells that operate at high (- 250° C) temperature, or less concentrated (35—50 wt %) KOH for lower (<120° C) temperature operation. The electrolyte is retained ia a matrix of asbestos (qv) or other metal oxide, and a wide range of electrocatalysts can be used, eg, Ni, Ag, metal oxides, spiaels, and noble metals. Oxygen reduction kinetics are more rapid ia alkaline electrolytes than ia acid electrolytes, and the use of non-noble metal electrocatalysts ia AFCs is feasible. However, a significant disadvantage of AFCs is that alkaline electrolytes, ie, NaOH, KOH, do not reject CO2. Consequentiy, as of this writing, AFCs are restricted to specialized apphcations where C02-free H2 and O2 are utilized. 

Measurement of E° and Activities Electrochemical cells can be constructed to measure E° and thermodynamic properties such as K, AG, AH, AS, A V, and ACP for a reaction. Consider as an example the cell shown schematically in Figure 9.4.x The cathode consists of an Ag metal rod coated with AgCl(s). The anode is a Pt metal rod around which H2(g) is bubbled. The two electrodes are... 

The behaviour [821] of AgN02 is closer to that expected of a nitro compound than a nitrite. Decomposition (308—363 K) yields Ag metal and N02. a—Time curves are sigmoid with a prominent linear region (0.15 < a < 0.45) but the Arrhenius plot was curved at >333 K. This was attributed to inadequate gaseous product removal. In contrast to the behaviour observed for most other solids, pre-irradiation with 7-rays inhibits subsequent thermal decomposition [829]. 

Now consider reduction. To show the addition of electrons to a species we write the corresponding half-reaction for electron gain. For example, to show the reduction of Ag4 ions to Ag metal we write... 

Sonomechanical-assisted metal displacement reduction technique Au, Pt, Ag, metal oxides [17, 18]... 

If 50.0g Zn is treated with 150g AgNO, how many grams of Ag metal can be prepared ... 

The Ag electrodes were subjected to potential sweep ORCs at 10 mV s"1 in either 0.1 M KC1 or 0.1 M KBr from an initial potential of -0.30 V to more positive potentials. After ca. 30 mC cm-2 of anodic charge was passed, the direction of potential sweep was reversed to reduce the Ag halide surface to Ag metal. The roughened electrode was then removed under potential control at -0.30 V and immersed in the Pb2+-containing test solution for SERS studies. 

The previous examples used the three-electrode electrochemical system. An alternative was utilized by Ajayan et al. to prepare Ag NP coated SWCNTs [217]. An electrode was fabricated consisting of SWCNTs attached to a Ti cathode and a silver contact pad as a sacrificial anode (Fig. 5.16(a)). The electrode was submerged in an aqueous solution and a potential was applied resulting in oxidation of Ag metal to Ag2+ ions which then subsequently deposited onto the SWCNT cathode. Although experimentally complicated, silver NPs, wires and patterns were controllably deposited on the SWCNTs (Fig. 5.16(a), (b)) [217],... 

Alkaline Fuel Cell (AFC) The electrolyte in this fuel cell is concentrated (85 wt%) KOH in fuel cells operated at high temperature ( 250°C), or less concentrated (35-50 wt%) KOH for lower temperature (<120°C) operation. The electrolyte is retained in a matrix (usually asbestos), and a wide range of electrocatalysts can be used (e.g., Ni, Ag, metal oxides, spinels, and noble metals). The fuel supply is limited to non-reactive constituents except for hydrogen. CO is a poison, and CO2 will react with the KOH to form K2CO3, thus altering the electrolyte. Even the small amount of CO2 in air must be considered with the alkaline cell. 

The manner in which contact is maintained between the Ag metal and the electrolyte. Since the volumes of the two phases must change... 

Figure 5.5. (a) TEM image of Ag/alumina catalysts (b) and (c) are the EDX spectra from and off the catalyst particle, respectively, indicating the Ag metal and the support (sample on Cu-grid). 

Negatively charged monolayers floating on an aqueous silver nitrate solution Ag Metallic silver particulate films generated electrochemically at monolayer surfaces could be transferred at any stage of their development to solid substrates 566, 567... 

Instant photography (e.g. of the Polaroid type) also relies indirectly on the silver halide process but here the reduced Ag (metallic silver) acts as a reducing agent to modify the solubility properties of a dye. The dye is linked covalently to a molecule such as a quinone (Figure 6.5), which is insoluble in water. When this is reduced to hydroquinone, it becomes soluble in alkaline solutions. The principle of this photographic process is the following ... 

Fig. 3.4 Correlation between the initial rate of photocatalytic Ag metal deposition (/JAg) and Ag+ adsorption ([Ag+]ads) of HyCOM Ti02 calcined at 973 K (open circles) and P-25 (closed circles).

FIGURE 7.45 Schematic showing the procedure used for the microfabrication of a thermocouple. The thermocouple, which consists of intersecting Ni and Ag metal lines, is fabricated by electrodeless metal deposition as masked by the PDMS channels [271]. Reprinted with permission from the American Chemical Society. 

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