Kinetics of electrochromic process in thin films of cathodically deposited nickel hydroxide

Ni(OH)₂ films have been obtained by cathodic deposition from 1 M Ni(NO₃)₂ on a glass with a current-conducting SnO₂ layer. The films have a porous structure and consist of chaotically joined formations of 100–150 nm in size. They contain a considerable amount of adsorbed water, because of which their refraction index was n?=?~1.5, whereas for crystalline nickel hydroxide, it was n?=?2.37. It has been shown that in the course of discoloration of films through a shift of their potential towards more negative values, an electric field is formed in the bulk of film, which accelerates the entry of cations into it (protons as [H₃O]⁺) from the electrolyte and electrons from ohmic contact. In this case, the initial dependence i(t), where i?~?t ^?1/4, is bound up with gradual increase in proton surface concentration. It is proposed to determine separately the dependence of the effective codiffusion coefficient of charge carriers (protons and electrons) on decoloration potential by the analysis of plots of current, injected charge, and luminous transmittance of films against time. This procedure involves a series of periodic stops of potential during the recording of current–potential curves for an electrochromic electrode and allows one to monitor the ratio of the film forms NiOOH and Ni(OH)₂ in the course of film reduction.     

Recovery of tungsten and cobalt from secondary raw materials by a combined electrochemical and chemical procedure

A combined electrochemical and chemical process was developed for the recovery of tungsten and cobalt from hard alloys of VK grades with the preparation of tungstic acid and cobalt oxalate as intermediates. The subsequent reduction of these intermediates in hydrogen yields metal powders of increased purity.     

Photoelectrochemical properties of the composites based on TiO2 nanotubes,CdSe and graphene oxide

Research on Chemical Intermediates - The photoelectrochemical properties of electrodes based on a nanocomposite consisting of TiO2 nanotubes and CdSe films modified with graphene oxide have been...     

Electrochemical deposition of electrochromic niobium oxide films from an acidic solution of niobium peroxo complexes

Deposition of electrochromic niobium(V) oxide films from an acidic solution of niobium peroxo complexes on a transparent conducting cathode in the form of an SnO₂ film on glass was studied. With an increase in the negative potential of the deposition of niobium(V) oxide films from a solution of niobium peroxo complexes at pH 2.5, the structure and composition of the films changed. A study of the electrochromic properties of Nb₂O₅ films revealed broadening of the bands in the electrochromic coloration spectrum with an increase in the negative potential of the deposition.     

Electrodeposition,optical and photoelectrochemical properties of BiVO4 and BiVO4/WO3 films

Research on Chemical Intermediates - BiVO4 films and BiVO4/WO3 heterostructure have been obtained by electrosynthesis method with the use of interferometric control of the thickness of films during...