Interactions of different nonylphenolepolyethyleneglycoles (NPG) with iron electrodes

Abstract

The difference in electroluminescence intensity for the peak obtained with the reduction of Fe(CN)i-and the hypohalites at n-GaAs cannot, however, be explained on the basis of Fig. 9. Although a change is observed in the mechanism of the second charge transfer step (from hole injection (3a) at low light intensity to electron capture (3b) at high light intensity) such a change is only expected after the masstransport limited current has been reached. That only very weak electroluminescence is observed in the onset of the hypohalite reduction at n-GaAs must therefore mean that the value of the rate constant for hole injection in the second step (kp2) is lower than for p-type GaAs. This might be due to an effect of the electric field on the hole injection rate. Adsorption f Corrosion Inhibitors / Corrosion / Electrochemistry / Inhibition / SurfactantsNonylphenolepolyethyleneglycoles (NPG) are characterized by means of electrochemical methods. We made electrochemical impedance spectroscopy and current density-potential measurements at superpure iron electrodes in K N 0 3 solution with and without addition of NPG. In order to acquire some knowledge about the electrical potential-distance profile at the electrode surface of iron, we made Zeta potential measurements at dispersed a-Fe203 particles. Adsorption phenomena of NPG at electrode surfaces free of any oxide layer were studied by a.c. polarography (tensammetry) at the dropping mercury electrode. It is shown that NPG can inhibit the corrosion reaction of superpure iron in neutral solutions as combined anodic/cathodic inhibitors, but increase the cathodic process in weak acid solutions.