Photoelectric Measurements during Corrosion and Inhibition of Copper in Aqueous Solutions

Abstract

Absorptionsspektren, sichtbar und ultraciolett 1 Elektrochetnie 1 Halhleiter 1 OherfluchenerscheinungenCopper electrodes were investigated in pure NaOH and halide solutions as well as in the presence of organic inhibitors using photocurrent, photopotential and modulated reflectivity measurements. The composition and the degree of oxidation of the surface layers were found to be dependent on the electrolyte composition and electrode potential. Optimum inhibiting efficiency was obtained when a p-type semiconducting surface layer, in connection with slow kinetics, was formed. It is presumed that this statement is also valid for other systems.

Investigation of Passive Electrodes Using Modulation Spectroscopy and Photopotential Measurements

“…The spectrum of the potential-modulated reflectivity is given in figure 3. In agreement with this statement different types of spectra are found which depend on the electrode potential [6]. In the potential region were a surface layer of cuprous oxide or a mixture of cuprous and cupric oxide should exist an oscillating structure is found, which is very similar to the electroreflectance spectrum of Cu20 single crystal electrodes [7].…”

“…Another oscillation is found at higher wavelengths with a sign change at about 550 nm, which fairy well corresponds with the band gap energy of cuprous oxide. The essentially good agreement proves in connection with photopotential measurements [6] that the surface is covered by a layer corresponding to the composition of Cu,O. In the potential region where the electrode is mainly covered with Cu(OH), a quite different spectrum is found, which shifts to shorter wavelengths with increasing electrode potential.…”

The Participation of Interfacial Hydrous Oxide Species in Some Anodic Reactions at Copper Electrodes in Base

“…5 in Ref. However, if the inner region of the oxide material is first reduced to Cu20 (or some of the latter is present as an inner layer in the initial deposit which may well be duplex (12) in character), then as Cu20 is a poorly conducting semiconductor (11,20), the outer region of the oxide material becomes electronically insulated from the metal surface. One might expect that since the cathodic sweep commenced at a high anodic potential, where most of the film is in the Cu(II) form, then the peak for reduction of the latter, i.e., C2, should at least be of comparable magnitude to C1.…”

In Situ Spectroelectrochemical Studies on Anodic Oxidation of Copper in Alkaline Solution

“…Although the rotating split ring-disk technique played an important role in identifying oxidation states of the products, nonelectrochemical techniques had to be brought in to identify the actual composition of anodic product films. These techniques include ex situ spectroscopic methods such as x~ray photoelectron spectroscopy (XPS; ESCA) and ion-scattering spectroscopy (ISS) (6)(7)(8)(9), and in situ techniques such as ellipsometry (10,12), electroreflectance (13), photoacoustic spectroscopy (14), and photocurrent spectroscopy (15,16). While ex situ spectroscopies can provide information as to the chemical composition of the corrosion product films at the time of examination, the composition may not necessarily represent the composition of product films in solution.…”