Formation of a photocatalytic WO(3) surface layer on electrodeposited Al–W alloy coatings by selective dissolution and heat treatment

In this study, we explored the feasibility of WO(3) surface layer formation on electrodeposited Al–W alloy coatings by selective dissolution and heat treatment, with the aim of providing corrosion-resistant Al–W alloy coatings with photocatalytic self-cleaning properties under visible light illumination. The selective dissolution of Al and oxidation of residual W was carried out by immersing Al–W alloy films in an aqueous solution of nitric acid. A nanostructured H(2)WO(4)·H(2)O surface layer was formed on the alloy film by this process. The H(2)WO(4)·H(2)O layer was dehydrated to WO(3) by heat treatment, yielding a multilayered WO(3)/Al–W alloy film with an approximately 300 nm thick WO(3) layer. The WO(3)/Al–W alloy film exhibited photocatalytic self-cleaning, as demonstrated by the photodegradation of stearic acid and methylene blue. We also confirmed that selective dissolution and heat treatment did not significantly diminish the corrosion resistance of the Al–W alloy films.