| The problem of environmental pollution caused by the rapid development of industrialization is becoming more and more serious.In recent years,photocatalytic technology has attracted much attention from scholars for its low energy consumption,simple operation and thorough degradation,and has been widely used in environmental protection,clean energy preparation and medical treatment.As a common photocatalyst,graphite phase carbon nitride（g-C3N4）is an organic metal-free polymer,which has attracted much attention due to its excellent visible light capture ability（2.7 eV）.Moreover,g-C3N4 has the advantages of non-toxic,low cost,easy synthesis and good thermal/chemical stability.However,the catalytic activity of g-C3N4 is inhibited due to its small specific surface area,narrow light response range and rapid recombination of photogenerated electron hole pairs.In this paper,g-C3N4 based composite photocatalysts with higher specific surface area,higher photo response range and lower recombination ratio of photogenerated electron hole pairs were prepared by modifying g-C3N4.The structure of the photocatalyst was characterized and its photocatalytic activity was tested.1)Ce O2/g-C3N4 composite photocatalysts were prepared by simple impregnation and thermal decomposition methods using Ce（NO3）3 and dicyandiamide as precursors.The structure,morphology,physicochemical properties and optical properties of Ce O2/g-C3N4 were characterized by XRD,XPS,SEM,mapping,TEM and UV-Vis.The results showed that the absorption threshold of Ce O2/g-C3N4 was blue shifted and the band gap was increased.When Ce O2 loading was 7%,the recombination rate of Ce O2/g-C3N4 electron hole pairs is the lowest,which improved the visible light activity of Ce O2;2)Ag/CN-x photocatalysts with different Ag contents were prepared by one-step calcination method with dicyandiamide and silver ammonia solution as precursors.The prepared catalysts were characterized by XRD,SEM,TEM,XPS and UV Vis.The results showed that the surface area of Ag/CN-x composite photocatalyst could be effectively increased by increasing the calcination time;3)The photocatalytic degradation of organic pollutants by Ce O 2/g-C3N4and Ag/CN-8 was tested.The results showed that the photocatalytic degradation of methyl orange（MO）by 7-CCN was 3.3 times higher than that of pure g-C3N4 under visible light（λ>420 nm）.At the same time,superoxide radicals play a leading role in the photocatalytic degradation of methyl orange by Ce O2/g-C3N4.The photocatalytic degradation efficiency of methyl orange by Ag/CN-8 under visible light was 7.2 times higher than that of pure g-C3N4.In the cycle experiment,Ag/CN-8 had strong cycle stability.In the capture experiment of Ag/CN-8 photocatalyst,the main active material is superoxide radical. |
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