Synthesis and properties of polyfunctional coatings on aluminum and titanium alloys

Abstract

This work presents the synthesis of highly active electrode materials for the electrolytic production of
hydrogen from aqueous solutions, which can also serve as photocatalysts. Composite coatings produced by
plasma–electrolytic oxidation on aluminum and titanium alloy substrates, doped with vanadium and tungsten
compounds, were investigated. The electrolysis processes of aqueous solutions using these composites as
electrode materials were analyzed. Linear voltammetry was applied to determine the Tafel equation constants
for the systems WO₃ – V₂O₅ – Al₂O₃/ Al and WO₃ – V₂O₅– TiO₂/ Ti, which are proposed as electrode materials for hydrogen evolution reactions. The study found that the dopant content, the metallic substrate characteristics, and surface morphology strongly influence the coatings’ functional properties. The Tafel coefficients a and b indicate a high level of electrocatalytic activity for the synthesized coatings, confirming their suitability as electrode materials for electrolytic hydrogen production. A comparison of photocatalytic activity in the methyl orange degradation reaction revealed higher activity of the aluminum-based coating than the titanium-based coating, highlighting the relevance of these materials for ecological technologies. The presence of nonstoichiometric oxides, compositional variability, morphological differences, and the developed surface area accounts for their exceptionally high electrocatalytic activity and, therefore, their strong potential for functional applications.