Electrosynthesis and characterization of lead dioxide–perfluorobutanesulfonate composite

The effect of potassium perfluorobutanesulfonate on the kinetic features of electrodeposition of lead dioxide from methanesulfonate electrolytes has been investigated. The introduction of C4F9SO3K into the lead dioxide deposition electrolyte leads to insignificant inhibition of the Pb2+ electrooxidation process, while the mechanism of the process does not change. A composite coating is formed upon deposition of coatings from electrolytes containing surfactants. The surface of a composite material consists of a mixture of clearly expressed large crystalline blocks with sharp angles and small crystals. Energy dispersive X-ray analysis revealed the satisfactory distribution of modifying elements in the entire sample bulk, and not only on the coating surface. It was shown that the electrocatalytic activity of lead dioxide–perfluorobuthanesulfonate composite differs from the undoped sample. The oxygen evolution reaction slightly decelerates on a PbO2–C4F9SO3K composite. The Tafel slopes in 1 M HClO4 calculated from these curves plotted in semilogarithmic coordinates are 136 and 145 mV dec–1 for undoped sample and lead dioxide-surfactant composite, respectively. The reaction of electrochemical oxidation of p-chlorophenol is characterized by the pseudo-first order kinetics with respect to the initial compound. The use of doped C4F9SO3K lead dioxide as an anode leads to the inhibition of the process of oxygen evolution and an almost one and a half higher rate of electrochemical conversion of 4-chlorophenol to aliphatic compounds.

Zinc-nickel alloy coatings: electrodeposition kinetics, corrosion, and selective dissolution. A review

A review of the literature is devoted to the patterns of the electrodeposition of zinc-nickel alloys including the kinetics of cathodic reduction of zinc, nickel, and zinc-nickel alloys in ammonium chloride, sulphate, and glycinate deposition electrolytes. We studied the data on the effectiveness of the corrosion resistance of zinc-nickel coatings and summarised the principal patterns of selective dissolution of the Zn-Ni alloys. The role of the addition of glycine to an ammonium chloride deposition electrolyte was determined in the modification of the morphological and anticorrosive properties of the coatings.

Electroless deposition of Ni-P on a silicon surface

The present article concerns the metallization of silicon substrates by deposition of the nickelphosphorus alloy produced by an autocatalytic chemical process. The deposition electrolyte is composed of a metal salt, a reducing agent (sodium hypophosphite), a complexing agent (sodium citrate) and a buffer (ammonium acetate). The deposition could only be carried out after activation of the silicon by fixing catalytic species on its surface. The immersion of the silicon samples in palladium chloride made it possible to produce relatively thick and regular Ni-P coatings. The immersion time was optimized. The activation of Si was characterized by XPS and the Ni-P coating by XPS and SEM. The electrochemical study did not show any real mechanism changes compared to the Ni-P deposition on a conductive surface.