Study On Enhanced Visible Light Photocatalytic Performance Of G-C₃N₄ Based On Heterojunction And Morphological Modification

In recent years,graphite-phase carbon nitride materials（g-C₃N₄）have attracted much attention from researchers due to their good stability,abundant precursor sources,and excellent photocatalytic performance.However,the shortcomings of g-C₃N₄,such as high recombination ratio,small specific surface area,and narrow response range in the visible region,which are greatly limited their photocatalytic efficiency.In view of these problems,the results show that g-C₃N₄based heterojunction constructing,morphology controlling and elements doping can be used to improvethe photocatalytic performance of g-C₃N_4.First,using other semiconductors with band-gap matching to build a heterojunction with g-C₃N₄can promote the generation and separation of photogenerated electron-hole pairs,broaden the visible light response range,and effectively enhance its photocatalytic activity.Secondly,the specific surface area of g-C₃N₄can be increased by morphological control,which provides more active sites for the degradation reaction,thereby improving its photocatalytic performance.In this dissertation,the g-C₃N₄/Cu₂O and MOFs-derived g-C₃N₄/Zn S heterojunction composites are constructed,and their morphological control methods are used to study their enhanced photocatalytic performance.The completed work is as follows:1.We developed a 2D/3D g-C₃N₄/Cu₂O heterojunction in situ construction method using melamine and copper nitrate as the main raw materials,and its physical and optical were studied.The results exhibit that the degradation rate of g-C₃N₄/Cu₂O-1:1composite for methyl orange can reach to 97%within 160 minutes,indicating that it has a higher photocatalytic activity in the visible light region.This can be attributed to the construction of 2D g-C₃N₄and 3D Cu₂O heterojunctions,the recombination of photo-generated electron-hole pairs is suppressed,and the visible light response range is widened.2.We constructed MOFs are used as self-sacrifice templates to prepare g-C₃N₄/Zn S photocatalysts via JRCL-DT mixer.The specific surface area of the composite was improved by introducing Zn S polyhedron with controlled morphology under magnetic stirring.The results indicate that the use of MOFs-derived Zn S and g-C₃N₄to build heterojunctions increases the specific surface area and provides a richer active site for the catalyst to contact with pollutants.Under visible light,the photocatalytic activity of g-C₃N₄/Zn S photocatalyst is 15 times than that of pure g-C₃N₄.This work provides new ideas for designing novel efficient photocatalysts.