Copper electrodes, surface chemistry

Fleischmann, M., Hendra, P.J., McQuillan, A.J. and Paul, R.L. (1975) Raman spectroscopy at the copper electrode surface. Journal of Electroanalytical Chemistry, 66 248. 

Scheme 3 accounts for the various products formed, and it is consistent with known transformations in organometallic chemistry. In the first step, CO2 is reduced in a proton-coupled two-electron process to form adsorbed CO. That CO is an intermediate in the reduction of CO2 to hydrocarbons is supported by the following observations. (1) Reduction of CO at copper electrodes under the same conditions gives a similar distribution of hydrocarbon products. Reduction of formate, on the other hand, gave no hydrocarbon products [98, 102]. (2) CO on the electrode surface could be detected by cyclic voltammetry measurements. Fourier transform... 

CO formation on copper electrodes appears to be accompanied by hydride formation as well [103]. In Sch. 3, the surface bound CO is reduced by a hydride transfer reaction to form a formyl species as shown in step 2. There are precedents in organometallic chemistry for late transition metal hydrides reducing bound CO [105-109]. Protonation of the adsorbed formyl in step 3 results in the formation of a hydroxy carbene species [110, 111]. This hydroxycarbene species could be considered to be an adsorbed and rearranged form of formaldehyde, and the reduction of formaldehyde at a copper electrode has been reported to form hydrocarbons [102]. However, reduction of... 

The electrochemical behavior of the powdered active carbon electrode depends on the surface chemistry, and cyclic voltammetry can be used as a simple method of characterizing active carbon materials. A new heterogeneous copper catalyst was developed using highly porous active carbon as the catalyst support [282]. The advantages of a porous-medium supported catalyst are that the active phase could be kept in a dispersed but stable state, and that, as an example, the oxidized organic pollutant is adsorbed onto carbon, thereby enhancing its surface concen-... 

More recently, Brennsteiner et al. [ 175] noted that the electrochemical removal efficiency for nickel is dependent on the pH of the contaminant solution. Maximum efficiency was achieved at pH = 7.0, but only when the carbon electrode was preplated with a layer of copper the role of surface chemistry was not investigated. Seco et al. [172] did characterize the surface chemistry of a commercial activated carbon (pHp r = 6.1) and studied its uptake of heavy metals (Ni, Cu, Cd, Zn), as well as of some binary systems. They interpreted the monotonic uptake increase with pH to be consistent with the surface complexation model a decrease in competition between proton and metal species for the surface sites and a decrease in positive surface charge, which results in a lower cou-lombic repulsion of the sorbing metal. In the binary uptake studies, they concluded that Ni (as well as Cd and Zn) is not as strongly attracted to the. sorbent as Cu. 

Welinder, A.C., Zhang, J., Hansen, A.G., Moth-Poulsen, K., Christensen, H.E.M., Kuznetsov, A.M., Bjornholm, T., and Ulstrup, J. (2007) Voltammetry and electrocatalysis of achromobacter xylosoxidans copper nitrite reductase on functionalized Au(lll) electrode surfaces. Zeitschriji jur Physikalische Chemie-International Journal of Research in Physical Chemistry ej Chemical Physics, 221,1343-1378. 

Mixed SAMs on gold electrodes from azido alkane thiols and various a>-functionalized alkanethiols were prepared. In the presence of copper(l) catalysts, these azide-modified surfaces are shown to react rapidly and quantitatively with terminal acetylenes forming 1,2,3-triazoles via click chemistry (Figure 6). In this way, thiol SAMs have been modified with complex functional molecules such as single-stranded DNA, porphyrin redox catalysts, and receptors for gold nanoparticles and other materials. 

Clad transition metal systems provide an interface between two incompatible metals. They not only reduce galvanic corrosion where dissimilar metals are joined, but they also allow welding techniques to be used when direct joining is not possible. Qad metals provide an ideal solution to the materials problem of dual environments. For example, in the application of small battery cans and caps, copper-clad, stainless steel-clad nickel (Cu/SS/Ni) is used where the external nickel layer provides atmospheric corrosion resistance and low contact resistance. The copper layer on the inside provides the electrode contact surface as well as compatible cell chemistry. The stainless steel layer provides strength and resistance to perforation corrosion. 

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