| At present,the increasingly serious problems of environmental pollution and energy shortage have increasingly hindered people's daily life.The rapid consumption of non renewable energy makes people feel the energy crisis.The development of new energy is conducive to the stable development of society and the stability and order of people's lives.Semiconductor photocatalysis technology can use solar energy to deal with pollutants,produce hydrogen and oxygen,alleviate the pressure of environment and energy.Among all kinds of photocatalysts,the new Bi-based photocatalyst is favored by researchers because of its unique layered structure and appropriate band gap.Bi?IO3?3,as a kind of Bi-based catalyst,contains an IO3 polarized group of lone pair electrons,which is conducive to the separation and transport of electrons and holes.It also has good chemical and optical stability,non-toxic,low cost and corrosion resistance,so it has great potential.However,there are many shortcomings in this material.At present,the catalytic activity of Bi?IO3?3 photocatalyst is not high enough,and the unmodified Bi?IO3?3 photocatalyst can only absorb ultraviolet light,and the composite efficiency of photogenerated electrons and hole pairs is high.Those weak points limit its application.In this paper,Bi?IO3?3 materials have been synthesized by hydrothermal method,and a variety of heterojunction photocatalytic materials have been constructed based on Bi?IO3?3.The details are as follows:?1?Bi?IO3?3 photocatalyst material was prepared by hydrothermal method,and Bi?IO3?3/BiOI composite material was prepared by hydrolysis method.The interface contact between Bi?IO3?3 and BiOI nanomaterials was observed by SEM and TEM,which proved the formation of heterojunction.The experimental result about degradation of methyl orange?MO?showed that Bi?IO3?3/BiOI composite photocatalyst with 1:3 ratio had the best photocatalytic performance and degradation efficiency.All the results show that the formation of heterojunction improves the absorption range of the material.Heterojunction is conducive to the rapid separation and transfer of photogenerated electrons and holes,thus improving the photocatalytic activity of Bi?IO3?3/BiOI composite.?2?Bi?IO3?3 and g-C3N4 were prepared by hydrothermal method and solid phase calcination method respectively.Bi?IO3?3/g-C3N4 composites with different proportions were prepared by ball milling.The phase composition was elucidated by XRD,and the interface contact between Bi?IO3?3 and g-C3N4 was observed by SEM,which demonstrated the formation of heterojunction.The degradation experiment of methyl orange?MO?showed that Bi?IO3?3/g-C3N4 composite sample with the ratio of1:1 had the best photocatalytic performance.All experimental results show that the absorption range of Bi?IO3?3/g-C3N4 composite is larger than the pure sample.the heterogeneity constructed by the composite modification method improves the separation efficiency of photogenerated electrons and hole pairs,which is conducive to the improvement of photocatalytic performance?3?Part of Bi?IO3?3 in 1:1 ratio of Bi?IO3?3/g-C3N4?graphite phase carbon nitride?was reduced to BiOI by thiourea to form Bi?IO3?3/g-C3N4/BiOI ternary complex.By adjusting the amount of thiourea to regulate the amount of I5+reduced,the best ternary compound ratio is 50%Bi?IO3?3/g-C3N4/BiOI,which has the best photocatalytic performance.The experimental results show that the photocatalytic activity of Bi?IO3?3/g-C3N4/BiOI ternary complex is better than that of Bi?IO3?3/g-C3N4 binary complex.The optimal ratio of samples can degrade 75%of MO within 2 hours.The mechanism analysis shows that the electron hole pairs produced in the photocatalytic process of the ternary complex can be effectively separated and the photocatalytic activity can be enhanced. |
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