Study On The Effect Of Bismuth Molybdate And Graphyne Doping On The Photocatalytic Performance Of Porphyrin MOF

With the help of visible light to catalyze the degradation of pollutants,abundant solar energy can be effectively used to achieve the degradation of organic pollutants in wastewater.The key to this technology lies in the development of efficient,stable and low-cost photocatalysts.At present,the problem of high photo-generated electron-hole recombination rate widely exists in catalysts.In this paper,the metal-porphyrin framework material PCN-222 sery materials are selected as the main body of the photocatalyst,and their composites with bismuth molybdate and graphdiyne have been studied respectively.A binary/ternary composite photocatalyst is prepared,which realizes the efficient catalytic degradation of Rhodamine B（Rh B）under visible light.The research explored the influence of the doped content of bismuth molybdate（Bi₂Mo O₆,BM）and graphdiyne on the catalyst performance,and compared the performance of binary/three-way catalysts.The specific research contents include:In chapter 2,bismuth molybdate was prepared by hydrothermal method,and tetracarboxyphenylporphyrin related molecules were synthesized;PCN-222-BM and PCN-222（Fe）-BM composite materials were prepared by the in-situ hydrothermal synthesis.The obtained samples were characterized,and the performance of the series of composite materials for catalytic degradation of Rh B under visible light were compared and studied.The degradation process was simulated by kinetics.The doping amount of BM was adjusted during the process,and the optimal BM doping amount in the composite material was studied.At the same time,combined with the results,the influence of the porphyrin central metal on the catalytic performance was analyzed.According to the results,it can be seen that after Fe is introduced into the porphyrin center,the catalytic performance is further enhanced.For the PCN-222（Fe）-BM composite material,when the BM doping amount is 7 mg,the material reaches the best catalytic performance,and its reaction kinetic constant is 1.39 times that of PCN-222（Fe）.In chapter 3,the graphdiyne（GD）film was prepared by the liquid-liquid interface method;the PCN-222（Fe）-BM7mg-GD composite material and the PCN-222（Fe）-GD composite material were prepared separately.The two series of materials include different doping amount of GD.The samples were characterized,and the performance of the two series of composite materials in the catalytic degradation of Rh B were compared.At the same time,combined with the first part of the work,the effects of the introduction of BM and GD were studied respectively,and the corresponding coefficients of action were determined.The GD composite amount was further explored on the catalyst performance.The main active intermediates in the photocatalytic process and the possible photocatalytic mechanism were determined through capture experiments.For the PCN-222（Fe）-BM7mg-GD composite material,when the doping amount of GD is 0.6mg,the photocatalytic performance of the material is the best,and its reaction kinetic constant is 2.49 times that of PCN-222（Fe）,and the material has good cycle stability.The above research shows that the introduction of other semiconductor materials into the structure of the PCN-222 series of MOF materials to prepare a heterojunction structure can effectively inhibit the recombination of photogenerated electrons and holes.At the same time,the introduction of GD is conducive to the transmission of photogenerated carriers and thus effectively improves its catalysis.In terms of performance,the synergy between the two is the key to improving catalyst activity.