Electrodeposition of Zn-V oxide composite from sulfate solutions

Electrodeposition of Zn with V was tried in un-agitated or agitated sulfate solutions containing Zn²⁺ and VO²⁺ at pH 0-3 and 40°C under galvanostatic conditions. XPS spectra of deposits showed that V was involved in deposited Zn in form of V oxide by hydrolysis of V ions. The content of V in deposits increased with increasing pH in solution and current density. These conditions appear to accelerate the hydrolysis of V ions as a result of an increase in hydrogen evolution in cathode layer. SEM and EPMA images of deposits revealed that V in deposits segregated at edge of layered platelet crystals of Zn. The agitation of electrolyte decreased the content of V in deposits, but decreased the segregation of V oxide. Anodic polarization curves for Zn dissolution in 3% NaCl solution were polarized by codeposition of V oxide with Zn in the range of V content less than 5 mass%. The corrosion current densities of deposits obtained from agitated solutions were smaller than those from un-agitated solutions.