J.A. Harrison

The oxidation of hydrazine on platinum in acid solution

Summary The oxidation of hydrazine on platinum in acid solution is controlled by the first electron transfer. The rate determining step involves an adsorbed species and is inverse first order in [H + ]. There is a small effect on the kinetics at low potentials by adsorbed H . and at high potentials by oxide.

Some observations on the inner layer at the mercury—Electrolyte interface

Abstract A simple model is developed to account for the inner layer entropy of formation of the Hg—electrolyte interface. It is shown that this two-state model, based on the orientational behaviour of the water molecules within the inner layer, cannot be used to describe simultaneously both the inner layer entropy and the differential capacity. The relationship of this model to those developed by previous investigators for the differential capacity is discussed.

The anodic dissolution of Pb in H2SO4

Summary The anodic dissolution of Pb in H2SO4 has been investigated. The Pb dissolves as Pb2+ and PbSO4 ions at low anodic potentials. At higher potentials solid PbSO4 is formed by a solid state reaction. PbSO4 can also be formed by a solution-precipitation mechanism.

The deposition of copper

Summary The kinetics of Cu deposition on a real Cu surface have been investigated by potentiostatic pulse, rotating disc and a.c. impedance techniques. The known mechanism for the electron transfer step in observed. Surface area changes similar to those investigated by the authors in other systems are a complicating feature of the reaction.

The formation of metal layers

Summary The deposition phenomena observed in the electrodeposition of deposits of Pb, Tl and Cd on to inert substrates of silver and lead are described for potentiostatic conditions. Under sweep conditions, Pb/Ag and Tl/Ag give rise to two peaks, whereas Cd/Pb gives only one. The first peaks are ascribed to the formation of monolayers of metal following the substrate profile; the second peak to multilayer formation with the deposit profile. Systems with large crystallographic dimensional differences are predicted to have only one peak. Phenomena observed in the first peak region are explained in terms of the growth of partial monolayers. Crystal growth processes are observed in the second peak-region, and the peak region for Cd/Pb, with extreme potential-dependence. This dependence is interpreted in terms of a fixed diffusion layer effect with the Nernst equation controlling the concentration at the interface. A model of defect generation explains the time-dependence of the transients.

Catalytic hydrogen evolution on ruthenium and platinum nuclei

Summary It is shown that thin layers of platinum and ruthenium on mercury behave differently from nuclei of the same metals grown on a carbon substrate. The mechanism of hydrogen evolution is controlled by the direct discharge of H + in the case of platinum and ruthenium on mercury, the relative current densities into edge and top of the two dimensional layers being about 100:1. In contrast, the hydrogen evolution reaction on platinum is controlled under all conditions by diffusion of molecular hydrogen. The reaction on ruthenium, at which the coverage by H is lower than platinum, appears to be controlled by H · + H + + e → H 2

Anodic dissolution of silver and formation of Ag2O in hydroxide solutions using single crystal electrodes a faradaic impedance study

Abstract Silver single crystal electrodes polarised anodically in strong NaOH solutions have been examined by the faradaic impedance method. In spite of some surface roughness it has been shown that dissolution of the electrode occurs as Ag(OH) − 2 at a rate too fast to measure. Dissolution precedes phase formation on the electrode which occurs firstly as a monolayer of Ag 2 O which, after a narrow potential range of stability, slowly thickens to form a dense multilayer. Dissolution continues to a reduced extent through the Ag 2 O film. There is no effect on the rate of a redox process during film formation even into the multilayer region and it must be that the film is an excellent electronic conductor. There are considerable surface roughness and area changes during dissolution and resulting from reduction of Ag 2 O layers.

The reduction of gold cyanide complexes

Summary Solutions of gold cyanide have been reduced at a rotating gold disc. A reaction mechanism is postulated in which the species undergoing reduction is AuCN which is in equilibrium with the bulk species Au(CN)2−.

The electrochemical growth of three dimensional nuclei during a potentiostatic pulse—A simulation

Summary A model for the three dimensional nucleation and growth of a solid phase under diffusion conditions is proposed. The model is used to predict the response to a potentiostatic pulse. A method for comparing experiment and theory is discussed.

The anodic oxidation of anisyl alcohol

Summary With a view to optimising the synthesis of anisaldehyde, the anodic oxidation of anisyl alcohol has been examined by preparative and kinetic techniques. A mechanism is proposed in which the fate of the radical cation determines the overall reaction product.