Preparation Of B/C/N Doped Composite Photocatalysts And Its Degradation Performance To Organic Compounds

As a clean,efficient and environmentally friendly catalytic redox technology,photocatalytic technology can be applied to photocatalytic degradation of organic pollutants in wastewater or waste gas.Among many photocatalytic materials,TiO₂ has become the focus of research with its advantages of non-toxic,harmless,efficient cleaning,easy preparation and good stability.However,there are two limitations to the application of TiO₂ in photocatalysis:the wide band gap limits the use of the catalyst for larger wavelengths of light;the photogenerated carriers are easily recombined,resulting in lower photon efficiency of the catalyst.In this paper,three elements of B,C and N were doped to modify the catalyst,which widened the range of photocatalytic response of the catalyst.And on this basis,the incorporation of Ag hinders the photo-generated carrier recombination and improves the photocatalytic performance of the catalyst.On the other hand,the catalyst surface adjustment is carried out by adding oleic acid/oleyl amine as a blocking agent.The heterophase interface heterojunction was constructed,which also hinders the recombination of photogenerated carriers and improves the photocatalytic performance of the catalyst.The paper is mainly composed of the following three parts:?1?B-C-N-TiO₂ catalyst was prepared,in which boric acid,glucose and ammonia were used as B source,C source and N source,respectively.The prepared catalysts were subjected to XRD,SEM,TEM,XPS,UV-vis DRS and electrochemical performance test.The catalysts were applied to a photodegradation MB experiment to detect the performance of the catalyst photodegradate organic matter.The experimental results show that the photodegradation rates of TiO₂,C-TiO₂,N-TiO₂,B-TiO₂ and B-C-N-TiO₂ are 0.00228,0.00667,0.00876,0.01089 and 0.01652min^-1,respectively.The photodegradation rates of C-TiO₂,N-TiO₂ and B-TiO₂ were2.93 times,3.84 times and 4.78 times of that of TiO₂,respectively.At the same time,the photodegradation rate of B-C-N-TiO₂ catalyst was 7.25 times of TiO₂,which is further improved than the single element doped TiO₂.And through the cyclic degradation experiment of MB,it is found that B-C-N-TiO₂ catalyst has good stability.?2?Ag/B-C-N-TiO₂ was prepared by using AgNO₃ as the Ag source and photoreduction deposition using an ultraviolet lamp.Characterization of Ag/B-C-N-TiO₂ catalyst shows that Ag can be introduced into the catalyst and exists as a zero-valent Ag.Ag/B-C-N-TiO₂ was applied to photocatalytic degradation experiment of MB to detect the activity of photocatalytic organic compounds.The results show that the incorporation of Ag increases the photocatalytic degradation rate of the catalyst,and the photodegradation rate is related to the amount of Ag.Ag/B-C-N-TiO₂ catalyst was also used for cyclic degradation experiment of MB.The results showed that the catalyst has good stability and has a certain guiding effect on the degradation of actual organic pollutants in the future.?3?Oleic acid/oleyl amine was used as a capping agent to regulate the crystal plane of B-C-N-titanium dioxide,which increased the proportion of{211}crystal plane.Characterization of the ratio of the{211}plane,the morphology,crystal plane and light absorption properties by XRD,SEM,TEM and UV-vis DRS.The results showed that the formation and growth of{211}crystal face are affected by the addition of oleic acid/oleyl amine.The morphology of the catalyst is also greatly affected by oleic acid/oleyl amine.The catalyst was applied to photocatalytic degradation of MB to detect the performance of photocatalytic organic compounds.The results showed that the catalyst for crystal plane control shows higher photocatalytic performance than B-C-N-TiO₂.Electrochemical tests showed that the catalyst of crystal plane control has a smaller impedance,that is,the catalyst of crystal plane control has a reduced photo-generated carrier recombination rate.Combined with HRTEM image analysis,the formation of heterophase surface heterojunction between{211}crystal plane and{101}crystal plane is an important reason for the obstruction of catalyst photo-generated carrier recombination.And the catalyst was used for cyclic degradation of MB experiments,and the results showed that the catalyst had good stability.