Optimization of two-scale oxide structure configuration for photocatalytic applications

Abstract

Photocatalytic active materials are very popular in the modern trend of increasing the environmental friendliness of production processes and vital activities. Effective photocatalysts are the oxides of certain metals (titanium, tungsten, zinc, etc.), which can be obtained by electrochemical methods. The additional use of photolithography to force irregularities on the surface of the photocatalyst with a given configuration increases the efficiency of purifying aqueous solutions under the influence of ultraviolet and visible radiation. The purpose of this work is to study the effect of substrate structuring on the liquid flow as part of a model experiment. Modeling in the COMSOL Multiphysics® software package was performed using the finite element method in the approximation of an absolutely incompressible fluid and a k-ε turbulence model. The results obtained made it possible to increase the efficiency of photocatalytic water purification in a flow system in the presence of a photocatalyst with a surface containing configuration elements in the form of ribs with gaps. The optimal dimensions of the ribs according to the results of estimating the liquid flow rate and the region of effective mixing were: rib height h = 0.25-1 mm, rib width w = 1 mm, intercostal gap g = 5 mm. The millimeter range of configuration elements' dimensions makes their manufacture simpler in comparison with the elements of micron and submicron dimensions and helps to expand the options for the technologies used to produce photocatalytic active substrates. In addition to photolithography and electrochemical methods, it is also possible to use chemical etching and sol-gel technology to obtain combined photocatalysts with a given surface configuration.

Keywords

• photocatalysis
• structuring
• modeling
• surface
• flow reactor
• water purification