Piotr Zabinski

Electrodeposition of Functional Ni-Re Alloys for Hydrogen Evolution

Alloys present very complex structures and properties, which crucially depend on their size, composition and chemical ordering, and which can therefore be tailored for specific and industrially relevant applications as in data storage, optical devices and catalysis. Electrodeposition of alloys containing platinum metals is in the forefront of research. The modulated structures are important because of their potential electrocatalytical properties. Deposition of active nickel alloy cathodes for hydrogen evolution in a concentrated sodium hydroxide solution was attempted by electrochemical method. The proper adjustment of the process of electrolysis has crucial role on the composition and structure of the deposited films, which decide about their electrocatalytic properties. The electrocatalytic activity towards the hydrogen evolution reaction is most likely related to the active surface area of the coatings (accounting for the porosity of the coatings and the presence of some nodules at the coatings surface). Magnetic field influence the electrodeposition of metals. The different magnetic force generates an additional convection, which can affect the morphology and composition of the deposit. Magnetic field applied parallel to the electrode generates an additional convection in the electrolyte caused by the Lorentz force, which acts on the ions. A laminar flow of ions in the electrolyte close to the electrode surface takes place. The magneto hydrodynamic effect (MHD) reduces the thickness of the diffusion layer and leads to an increasing concentration gradient, which should have an effect on the morphology and composition of the deposit. Superimposed B can influence the texture and the phase formation of electrodeposits. The whole electrodeposition process is also influenced by the additional convection. In the present investigation, the changes in composition of the electrolyte and current density significantly affect on the composition and structure of the Ni-Re alloy. The strong effect of electrolyte composition and current density of the electrolysis on composition, structure of the films were observed. The electroactivity of the coatings were analyzed in 8 M NaOH solution under galvanostatic conditions. We try to analyze the effect of the platinium group metal addition in enhancing the activity for hydrogen evolution and in changing the morphology of electrodeposits observed by SEM and AFM microscopy. The influence of magnetic field on morphology, structure and electrocatalytical properties of alloys is also discussed.