Dynamic technique for two-wave monitoring of photocatalytic activity of titanium oxide films with the ability to determine the degree of mineralization

A dynamic technique for two-wave monitoring of the photocatalytic activity of titanium oxide films, which makes it possible to determine the degree of mineralization, is presented. The relevance of the work is dictated by the need to move from qualitative characteristics of photocatalysis to strict quantitative ones. The creation of a technique that combines the assessment of the rate of decomposition with the direct determination of the released CO 2 or the reduction of total organic carbon, and its testing, makes it possible to obtain objective data on the effectiveness of TiO 2 films. This is important not only for a fundamental understanding of the mechanisms of photocatalysis, but also for the certification of materials for use in water and air purification systems or in the creation of coatings with a self-cleaning effect. Measuring equipment for implementing a dynamic technique for two-wave monitoring of the photocatalytic activity of titanium oxide films is described. It is shown that the film synthesized by reactive magnetron sputtering exhibits a twice as high photo destruction rate constant as compared to the commercial analogue, which indicates faster bleaching of the solution due to dye decomposition. At the same time, the degree of mineralization for the experimental sample reaches about 60% versus 25 % for the standard. This means that the experimental film not only degrades the dye molecules faster, but also degrades them more completely into non-toxic end products, whereas the sample with certified photocatalytic activity is largely limited to the formation of intermediates detected at a wavelength of approximately 440 nm. Thus, application of the technique makes it possible to draw a reasonable conclusion that the film formed by reactive magnetron sputtering is superior to an analogue with known photocatalytic activity both in the rate of primary decomposition of the dye and in environmental efficiency, which characterizes the completeness of organic pollutants mineralization.