Preparation Of Composite Photocatalytic Films By PEO Technique Combined With Post Treatment And Their Performance

Plasma electrolytic oxidation（PEO）is a simple and environmentally friendly technology for preparing oxide film with improved surface performances in terms of strong adherence and good corrosion resistance.Furthermore,a tailored PEO film can be obtained by adjusting reaction parameters.In recent years,PEO technique is attracting increasing interest for its use in catalysis and is thought to be a promising approach for obtaining catalyst.In order to better apply PEO technology to practice,many researches focused on the subsequent modification of PEO films.The composition and microstructure of the films are changed by post-treatments,and some new composite catalytic films with specific structure and higher catalytic activity are prepared,which further realize the functional application of PEO films.In this paper,composite photocatalytic films were prepared by using PEO combined with post treatment.The effects of temperature on the microstructure,crystal phase composition,optical properties and catalytic properties of the films were studied.The main research contents are summarized as follow:（1）Fe₂O₃/TiO₂ nanosheets films were prepared by PEO combined with hydrothermal treatment.The results showed that high density of nanosheet structures with orderly arrangement and uniform size were formed on the surface of Fe₂O₃/TiO₂film after hydrothermal treatment.The size of nanosheets become bigger and bigger with the increase of hydrothermal temperature.When the hydrothermal temperature reaches 180℃,the surface of the porous film is covered with biggest nanosheets.Fe₂O₃/TiO₂nanosheets films are mainly composed of anatase TiO₂.With the increase of hydrothermal temperature,the intensities of anatase TiO₂diffraction peaks increase as well,and the mechanism of film formation was proposed based on the characteristics of PEO reaction.The photocatalytic results showed that Fe₂O₃/TiO₂nanosheets films have higher photocatalytic activity,and the sample prepared under hydrothermal treatment temperature of 160℃showed the highest photocatalytic activity.Furthermore,the cyclic degradation experiment proves the sample has good stability.（2）CuO/WO₃/TiO₂ composite film were prepared by PEO combined with impregnation-heat treatment.The results showed that CuO/WO₃/TiO₂film exhibit porous structure and many nanoparticles are distributed on its surface and pores.As the heat treatment temperature increases,the nanoparticles began to aggregate.The phase composition of CuO/WO₃/TiO₂films is the mixed phase of anatase,rutile and CuO,the mechanism of film formation reaction was proposed.The elemental analysis showed that the content of active components such as W and Cuincreased with the temperature.CuO/WO₃/TiO₂films showed a high absorbance in the visible region.With the increase of heat treatment temperature,the absorbance in the visible region increased first and then decreased,and the sample prepared at 750℃ had the highest peak absorbance.The results of photocatalytic test showed that CuO/WO₃/TiO₂films have good catalytic activity,and the sample prepared under heat treatment temperature of 750℃ showed the highest photocatalytic activity.