Preparation And Properties Of Delafossite CuGaO₂ Photocatalytic Materials

Recent years have witnessed serious restriction of energy crisis and environmental pollution on the survival and development of human beings.Photocatalytic technology as been widely concerned by researchers at home and abroad since the use of solar energy can not only decompose aquatic hydrogen to alleviate the energy crisis but also degrade pollutants to purify the environment.The delafossite CuGaO₂ semiconductor photocatalytic materials,for their quasi-two-dimensional layered structure and the potential to respond to visible light,have attracted extensive attention.Although the delafossite CuGaO₂ material boasts many advantages(relatively high hole mobility,excellent chemical stability,etc.) as well as a wide range of applications(transparent conductive oxides,various types of solar cells,etc.),researchers have found in the study of materials in delafossite CuGaO₂,the band gap and performance are quite different.The main reason is that the current research on the basic physico-chemical properties of the delafossite CuGaO₂ has not drawn a clear and accurate conclusion.Therefore,in order to better explore the photocatalytic potential of delafossite CuGaO₂ under visible light,this paper conducts research through the following three aspects:(1)Experiments and theoretical calculations were conducted to systematically study the basic physico-chemical properties of pure-phase delafossite CuGaO₂ crystallites.The results show that the single-phase 3R delafossite CuGaO₂ crystallite with high crystallinity can be prepared by hydrothermal method.Experimental optical property characterization and density functional theory were combined to prove that the minimum indirect band gap and the minimum direct band gap of the material were 1.378 and 2.467 eV respectively,and the light absorption in the visible region mainly came from the indirect transition of electron from the valence band to the conduction band.The carrier concentration and photocurrent density of 3R delafossite CuGaO₂ microcrystals were 1.54×10²¹ cm^-3 and 21?A/cm² by electrochemical photochemistry and photocatalytic activity test,and it was proved that 3R delafossite CuGaO₂ microcrystals were a potential and promising photocatalyst driven by visible light,which laid a solid foundation for further exploration of delafossite CuGaO₂ photocatalytic potential of delafossite CuGaO₂(2)Modification studies were carried out based on the content(1)of preparing pure-phase delafossite CuGaO₂ crystallites.with the proposition of a method of adding ethanol to a solvent and changing the volume ratio of ethanol to water to prepare CuGaO₂ photocatalytic materials with different aspect ratios.The experimental results show that ethanol not only plays the role of solvent but also acts as a surfactant in regulating the growth of delafossite CuGaO₂ crystals.With the increase of the ratio of ethanol to water,the prepared delafossite CuGaO₂ samples exhibited characteristics of nanosheets with adjustable aspect ratio in morphology.Due to the thin layered design of CuGaO₂ nanosheets and the adjustable aspect ratio caused by preferential growth,the results of electrochemical,photoelectrochemical and photocatalytic activity tests found that compared with CuGaO₂ crystallites,the carrier concentration,photocurrent density and photocatalytic degradation activity of CuGaO₂ nanosheets with the largest aspect ratio(60 for aspect ratio) were increased by 3.8 times,2.1 times and 2.6 times respectively.(3)The delafossite CuGaO₂ nanosheets with the best photocatalytic performance were selected from the content(2)to form a CuGaO₂/TiO₂ hetero-structure with the anatase TiO₂ to further enhance the photocatalytic performance of the delafossite CuGaO₂.To this end,by virtue of the microstructure characterization,this thesis proves that a pure-phase CuGaO₂/TiO₂ hetero-structure photocatalyst with high crystallinity was prepared experimentally,and the photoelectrochemical and photocatalytic performance test characterization reached the finding that the construction of CuGaO₂/TiO₂ hetero-structure resulted in a strong interaction at the interface,producing a built-in electric field and further improving carrier separation efficiency.This has increased the photocurrent density of the CuGaO₂/TiO₂ hetero-structure by 1.24 times and the photocatalytic degradation activity by 1.3 times.The above research results would provide new research ideas and research cases for the further development of highly efficient photocatalytic materials of layered structure.