Electrochemical Behaviour Of Nickel Research Articles

Etude des transformations de quelques proteines au contact du nickel

The purpose of this paper is to study the alteration of some proteins which are in contact with nickel for some time. On the one hand the UV spectroscopy gives us some indications on the modification of biological molecules. On the other hand, the electrochemical behaviour of nickel in protein solutions shows that these molecules may participate to the charge transfert, and also, in some case, to the mass transfert. An important feature of the results is that the biological molecules may be adsorbed on the metal surface, in a large potential range, and so, participate directly to the nickel electrochemical dissolution.

The kinetics and mechanism of the nickel electrode—III. The potentiodynamic response of nickel electrodes in alkaline solutions in the potential region of Ni(OH) 2 formation

The electrochemical behaviour of nickel in alkaline aqueous solutions within the anodic potential range yielding Ni(OH) 2 and under different potentiodynamic perturbations profiles has been investigated. The formation of Ni(OH) 2 is characterized by an irreversible anodic current peak which is quantitatively interpreted in terms of a complex reaction pathway involving different hydroxoadsorbed species.

The effect of chloride ions on the electrochemical behaviour of nickel at mercury electrodes,

The behaviour of Ni(II) and Ni(0) has been studied in aqueous solutions of mixtures of LiCl and LiNO3 at chloride concentrations up to 14 M, by using combined techniques (d.c. and pulse polarography, double potential step chronocoulometry and chronopotentiometry). The kinetics of the reduction process is controlled by the chloride and free water contents. At constant water activity, reaction orders, with respect to chloride bulk concentration, are +1. At high chloride concentrations, Tafel plots yield two straight lines with respective slopes of 43 and 170 mV. The data are explained by assuming that the chemical reaction [Ni(H2O)6]+ + Cl−⇌[Ni(H2O)5Cl]+ + H2O precedes the bielectronic reduction with the apparent values of the transfer coefficients α→1=0.35 and α←2=0.4. Reoxidation of cathodically generated Ni(0) gives Tafel slopes, which are characterized by an apparent α of about 0.4, a very small water effect and a chloride reaction order of +1. These facts are explained by assuming that the rate determining step consists in the chloride-assisted electron abstraction Ni+Cl−-e→NiCl. A reaction mechanism is proposed, with the chloride ion acting as a catalyst and Ni +Cl− − e⇌NiCl as the slow step of the charge transfer process.

The effect of chloride ions on the electrochemical behaviour of nickel at mercury electrodes

Summary The behaviour of Ni(II) and Ni(0) has been studied in aqueous solutions of mixtures of LiCl and LiNO 3 at chloride concentrations up to 14 M , by using combined techniques (d.c. and pulse polarography, double potential step chronocoulometry and chronopotentiometry). The kinetics of the reduction process is controlled by the chloride and free water contents. At constant water activity, reaction orders, with respect to chloride bulk concentration, are +1. At high chloride concentrations, Tafel plots yield two straight lines with respective slopes of 43 and 170 mV. The data are explained by assuming that the chemical reaction [Ni(H 2 O) 6 ] + + Cl − ⇌[Ni(H 2 O) 5 Cl] + + H 2 O precedes the bielectronic reduction with the apparent values of the transfer coefficients α → 1 = 0.35 and α ← 2 = 0.4 . Reoxidation of cathodically generated Ni(0) gives Tafel slopes, which are characterized by an apparent α of about 0.4, a very small water effect and a chloride reaction order of +1. These facts are explained by assuming that the rate determining step consists in the chloride-assisted electron abstraction Ni+Cl − - e →NiCl. A reaction mechanism is proposed, with the chloride ion acting as a catalyst and Ni +Cl − − e ⇌NiCl as the slow step of the charge transfer process.