Anodic growth of nanoporous WO3 films: Morphology, photoelectrochemical response and photocatalytic activity for methylene blue and hexavalent chrome conversion

This study first probes the relationship between the morphology of anodic tungsten(VI) oxide (WO3) layers grown on tungsten foil substrates and their subsequent photoelectrochemical response in 0.5 M Na2SO4 supporting electrolyte. The effects of anodization variables (voltage and time) and anodization medium composition [poly(ethylene glycol), ethylene glycol] on the oxide layer morphology and photoresponse are described. Selected anodic samples were then tested for their photocatalytic activity using methylene blue and hexavalent chromium as probes. Kinetics parameters are presented from data on the dye using variant concentrations and analyzed within the framework of the Langmuir–Hinshelwood model. The anodic nanoporous WO3 showed better photocatalytic activity for the reductive conversion of Cr(VI) when compared with a cathodically electrosynthesized film counterpart.