10 research outputs found
Development and electroanalytical investigation of a novel rectifying semiconductor/polymer interface
No full textInfluence of temperature and of structure of antimony substrate on gallium diffusion into the GaSb semiconductor compound
No full textA Review of Nanostructural Aspects of Metal Electrodeposition
No full textIn this review we address the electrochemical growth of metals and alloys with nanometric structures controlling the functional properties of electrodeposited coatings and freestanding electroforms. Electrodeposition is starting to be regarded as a viable process for nanofabrication and - even though electrocrystallisation has received considerable attention from both the theoretical and experimental viewpoints - it is now worth focussing systematically on the role of processing and electrochemical engineering factors, in the tailoring of nanosized structural features. This information is currently scattered in the literature and a specific review would fill an information gap. This paper offers: (i) an overview of the tools currently avaliable for the description and in-situ and ex-situ assessment of the nanostructure of electrodeposited metals; (ii) a systematic discussion of the relationships among their nanostructure and mechanical and chemical properties; (iii) a rationalisation of the mechanisms of formation of the different types of nanoelectrodeposits; (iv) a critical presentation - ordered by chemical composition - of specific systems. An updated and comprehensive literature coverage is provided, based on over 300 papers
Influence of the structure of the electrodeposited antimony substrate on indium diffusion
No full textHydrogen evolution reaction on ferritic stainless steel
No full textFollowing a preceding research on austenitic and martensitic stainless steels, the hydrogen evolution reaction on ferritic stainless steel has been investigated.Ferritic stainless steel was strongly corroded in sulphuric acid solutions; nevertheless a linear Tafel behaviour was observed, albeit in a limited range at high cathodic potentials. The values obtained for the Tafel slope and the electrochemical reaction order with respect to the hydrogen ions were 140 mV and 0.89 respectively. From these data, and taking into account some general considerations on the coverage of the electrode surface with atomic hydrogen, it was possible to conclude that the reaction proceeds according to the proton discharge-electrochemical desorption mechanism and that the second step is the rate determining one.Ferritic stainless steel was initially covered with an oxide film which is easily reducible cathodically in sodium hydroxide soutions. From the measurements on an oxide free surface the values of 100 mV and 0.39 for the two kinetic parameters considered in acid solutions were obtained. These results support the conclusion that the mechanism is the same as in acid solutions, while the surface coverage is lower than found in acid solutions, i.e. intermediate
Hydrogen evolution reaction on martensitic stainless steel
No full textFollowing a preceding research on austenitic stainless steel, He hydrogen evolution reaction on martensitic stainless steel in sulphuric acid and in sodium hydroxide solutions was investigated.In acid solutions the electrodes were corrodible and a linear Tafel behaviour was observed only at higher cathodic potentials. The values found for the Tafel slope (120 mV) and for the electrochemical reaction order with respect to the hydrogen ions (0.96), together with some considerations on the coverage of the electrode surface with atomic hydrogen, enabled us to conclude that, as for austenitic stainless steel, the process takes place according to the proton discharge-electrochemical desorption mechanism, the latter being the rate determining step.In alkaline solutions the electrodes were initially covered with an easily reducible oxide film and, contrary to the austenitic stainless steel, it was thus possible to carry out the measurements on an oxide free surface. The values found for the same parameters taken into consideration for acid solutions were 85-90 mV and 0.50.Based on these results the mechanism and the rate determining step were assumed to be the same as in acid solutions, whereas the surface coverage of the electrode with atomic hydrogen was assumed lower, i.e. intermediate
