Cu electrode

Electroreflectance data for pc-Cu579 confirm that the capacity minimum at E- -0.2 to -0.3 V (SCE) is due to the oxidation of the electrode surface. According to impedance data,564,565 as for pc-Ag and pc-Au,63 67 74 roughness factor for a pc-Cu electrode is approximately 2, which has been explained by the high surface inhomogeneity of the electrode surface. 

Using impedance data of TBN+ adsorption and back-integration,259,588 a more reliable value of <7 0 was found for a pc-Cu electrode574,576 (Table 11). Therefore, differences between the various EffM) values are caused by the different chemical states and surface structures of pc-Cu electrodes prepared by different methods (electrochemical or chemical polishing, mechanical cutting). Naumov etal,585 have observed these differences in the pzc of electroplated Cu films prepared in different ways. 

Cu crystallizes in the fee and its melting point is 1356 K. The experimental data for single-crystal Cu/H20 interfaces are also controversial. 567 570,572 57X The first studies with Cu(l 11), Cu(100), and Cu(l 10) in surface-inactive electrolyte solutions (NaF, Na2S04) show a capacitance minimum at E less negative than the positive limit of ideal polarizability of Cu electrodes (Table 11). depends on the method of surface... 

Gregory WB, Norton ML, Stickney JL (1990) Thin-layer electrochemical studies of the underpotential deposition of cadmium and tellurium on polycrystalline Au, Pt and Cu electrodes. J Electroanal Chem 293 85-101... 

In case (a), the galvanic cell under non-faradaic conditions, one obtains an emf of 0.34 - (-0.76) = 1.10 V across the Cu electrode ( + pole) and the Zn electrode (- pole). In case (b), the galvanic cell with internal electrolysis, the electrical current flows in the same direction as in case (a) and the electrical energy thus delivered results from the chemical conversion represented by the following half-reactions and total reaction, repsectively ... 

Melendres et ai (1991) reported the in-situ study of the electrode/oxide and oxide/electrolyte interfaces for a copper electrode in pH 8.4 borate buffer under potential control. The grazing-angle incidence arrangement employed by the authors is shown in Figure 2.81(a) and a cyclic voltammogram of the Cu electrode in the buffer is shown in Figure 2.81(b). 

Pettinger B., Wenning U., Wetzel H., Surface-plasmon enhanced Raman-scattering frequency and angular resonance of Raman scattered-light from pyridine on Au, Ag and Cu electrodes, Surf. Sci. 1980 101 409-416. 

Ru electrodes were prepared as previously described by plating Ru metal onto spectroscopic carbon rods, except for the electrode used for Auger analysis (before and after carbon dioxide reduction) which was plated on Ti (2.). Cu electrodes were prepared from Cu foil as previously described (Kim, J. J. Summers, D. P. Frese, K. W., Jr. J. Electroanal- Chem. in press.). Each entry in the tables and figures was obtained on different days with the electrode kept in ordinary laboratory air overnight between runs. 

The next step was to alternate the deposition of Cd and Te. As Te is more noble than Cd, various amounts of Te were first deposited and then exposed to a Cd ion solution at underpotential. Figure 8 is a graph of the Cd coverages observed to form on a Cu electrode initially coated with various amounts of Te. The slope of the graph is 0.95 (the Cd/Te ratio), which is consistent with the Cd reacting 1 1 with the Te. Similar results were observed for deposits formed on Pt and Au electrodes. The graph indicates that the Cd reacted at underpotential quantitatively with the Te, even when multiple atomic layers of Te were present. 

Figure 5.11 Desorption of a SAM of dodecanethiolate from a rotating Cu-disk electrode, (a) Current measured at the Cu electrode, (b) Current measured at a Au-ring electrode indicating oxidative adsorption of a thiol. Electrolyte 0.1 NaOH + H2O (5%) in methanol. Reproduced with permission from Ref [165].

Cd ion-selective electrodes The usual version of the Cd " ISE contains a membrane of a sintered or pressed mixture of CdS and Ag2 S [121, 325,408]. Membranes from sintered Ag2S, CuS and CdS mixtures [157] have also been proposed, similarly as forPb ISEs. CdS precipitate in a polyethylene matrix [250] or a CdS-Ag2S precipitate mixture in a silicone rubber matrix [153] can also be used for Cd ISEs. Cd ISEs can be calibrated using a metal diethylenetriamine buffer [66]. Similar substances interfere in the response of the Cd ISE as for the Hg, Ag and Cu electrodes. 

Figure 2. Steady-state cyclic voltammograms of Cu electrodes, both bare and coated with thick films (approximately 15 pm) of BTA, PVI-1, or UDI in 0.1 M HCIO, in air, v = 50 mV/s, w = 15 Hz, 25 "C. ...

Upon removing the coated Cu electrodes from after treatment, it was observed that PVI-1... 

They found that a Cu electrode, pretreated by immersing it in a 0.1M BTA solution for 15 seconds, inhibited the 0 reduction reaction initially and that on subsequent cycles the currents Increased to that of bare Cu in a short time. A similar effect was observed when a Cu electrode was cycled in a ImM solution of BTA. They discovered that a solution of 0.1M BTA produced a lasting effect, indicating that a reservoir of BTA is necessary for continuous protection of the copper against corrosion. We found that bare Cu gives the same voltammogram in the 0 reduction region in both acetate buffer and phosphate buffer therefore, McCrory-Joy et. al. s results can be directly compared to the results reported here. 

Figure 7. Levich plot of bare Cu electrode to obtain through ij values in 0.1 M HCIO in air, v = 5 mV/s, 25 C.

Figure 8. Tafel plots of oxygen reduction on Cu electrodes in 0.1 M HCIO, in air, w - 15 Hz, 25 C. bare Cu, o BTA-coated Cu, APVI-T-coated Cu, UDI-coated Cu. log i was used since no mass transport limited behavior was observed.

Figure 9. Tafel plots of oxygen reduction Cu electrodes in phosphate buffer, pH = 5.6, w = 15 Hz, 25 °C. bare Cu, ...

Let us now consider a galvanic cell with the redox couples of equation 8.164. This cell may be composed of a Cu electrode immersed in a one-molal solution of CUSO4 and a Zn electrode immersed in a one-molal solution of ZnS04 ( Dan-iell cell or Daniell element ). Equation 8.170 shows that the galvanic potential is positive the AG of the reaction is negative and the reaction proceeds toward the right. If we short-circuit the cell to annul the potential, we observe dissolution of the Zn electrode and deposition of metallic Cu at the opposite electrode. The flow of electrons is from left to right thus, the Zn electrode is the anode (metallic Zn is oxidized to Zn cf eq. 8.167), and the Cu electrode is the cathode (Cu ions are reduced to metallic Cu eq. 8.168) ... 

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