A Study of the Influence of the Hydrodynamic Conditions of Formation on the Morphology and Photocatalytic Properties of Anodic Tungsten Oxide

Anodization of transition metals is a widely used method for producing nanostructured oxides with high aspect ratios, such as porous alumina or titanium oxide. However, during the synthesis of porous tungsten oxide in the process of electrochemical oxidation, difficulties arise due to diffusion limitations: difficulty in supplying reagents and removing reaction products. Technological modes of anodic oxidation of tungsten, which allow the formation of layers of porous tungsten oxide with a high specific surface area by changing the hydrodynamic conditions of the process, including electrode rotation, are currently poorly studied and are practically not presented in the literature. The paper examines the influence of hydrodynamic conditions of tungsten anodization on the growth kinetics and morphology of porous tungsten oxide WOx in a cell with a rotating disk electrode. The morphology of the obtained oxide layers of anodic tungsten oxide WOx was studied using scanning electron microscopy. It has been shown that, in the range of rotation speeds of the tungsten electrode of 500–750 rpm, the formation of porous WOx structures is possible with a pore diameter of 40–70 nm and a high specific surface area. It has been demonstrated that such oxide structures have a higher photocatalytic activity than samples obtained at other electrode rotation speeds.