| One of the challenges in chemistry is the development of renewable and green energy based processes.Heterogeneous photocatalysis can provide a new and green synthetic method since it requires milder conditions,allows shorter reaction sequences minimizing side processes and avoids the rigorous conditions with high temperature or high pressure and complicated steps in the traditional organic progess.These measures should go far towards solving a series of energy waste and environmental pollution problems that caused by traditional organic production progess.The key of the application of photocatalytic technology for oxidation reduction is to develop new and efficient visible light responded photoccatlysts.The vigorous development of Metal-Organic Framework?MOFs?has brought new hope for the development and application of new photocatalysts.In view of that,the present work focuses on the design and synthesis the conjugated polymers/MOFs nanocomposites photocatalysts to the application for the selective oxidation of aomatic alcohol to the corresponding aldehydes or ketone and the reduction of aromatic nitro compounds to the aromatic amine compounds.We have further studied the internal relationship between the structure of the photocatalysts and the catalytic performance.The main contents and results of present study are as follows:1.A series of MIL-53?Fe?-graphene nanocomposite photocatalysts were synthesized by a facile one-pot solvothermal reaction.The structure,morphology and optical properties of MIL-53?Fe?-graphene nanocomposite photocatalysts have been thoroughly characterized by FT-IR,SEM,TEM,XRD,UV-vis DRS and PL analysis.It was demonstrated that the effective interface between the GR and MIL-53?Fe?could be formed.The introducing of graphene on the surface of MIL-53?Fe?would minimize the recombination of photogenerated electron-hole pairs and lead to the enhancement of photocatalytic activity.MIL-53?Fe?-graphene nanocomposite was an efficient catalyst towards the photocatalytic selectively oxidation of alcohols to the corresponding aldehydes or ketones under visible light and ambient conditions.From the photocatalytic mechanism,it was demonstrated that a direct photogenerated hole-oxidation process to realize the selective oxidation of oxidation of alcohols.It would be used as a potential and promising strategy for the selective oxidation of alcohols.Therefore,this study provides new physical insights for design and choice novel visible light active MOFs based photocatalyst.2.In view of thermodynamic,the band structure of UiO-66 meets the basic conditions for the reduction of nitrobenzene to aniline.In order to further improve the photocatalytic performance of UiO-66,firstly,Ce has been doped into the UiO-66skeleton.Following the first part of research,corresponding graphene hybridized GR/Ce-UiO-66 nanocomposites were further facilely synthesized by means of one step solvothermal reaction.The structure,morphology and optical properties of GR/Ce-UiO-66 nanocomposites have been thoroughly characterized by FT-IR,SEM,TEM,XRD,UV-vis DRS and PL analysis.Moreover,thus produced nanocomposite could be used as highly efficient and chemical stable photocatalyst for the reduction of nitroaromatic compounds under visible irradiation and ambient conditions.Through the study of mechanism,it is demonstrated that compared with the bare UiO-66,Ce-doped UiO-66/graphene nanocomposites distinctly enhanced photocatalytic activity.Ce as“mediator”introduced into the MOFs materials can greatly improve the electron transfer across the interface between grephene and the UiO-66 and further improve the visible light driven photoactivity.3.Extended the second part of this work,we have introduced the Fe3+into the skeleton of UiO-66.New hybrid MOFs,iron doped zirconium based metal-organic frameworks?FeUiO-66?were successfully synthesized by hydrothermal method.Then the PANI/FeUiO-66 nanohybrids were fabricated through annealing the mixture of FeUiO-66 and PANI.The structure,morphology and optical properties of PANI/FeUiO-66 nanohybridS have been thoroughly characterized by FT-IR,SEM,TEM,XRD,BET,UV-vis DRS and PL analysis.PANI/FeUiO-66 composites have high photoactivity for oxidation of alcohols under visible-light irradiation.From the analysis of the mechanism,it is known that by virtue of unique advantage of the position of the conduction band and valence band for the FeUiO-66,alcohols could be selectively oxidized by the·O2-and h+.Last but not least,this study is a good example showing that MOFs-conductive conjugated polymers can be a class of efficient photocatalyst for oxidation of alcohols with high selectivity and environment friendly conditions,and it should open up the opportunities to the development of various MOFs based visible light photocatalysts for organic transformations in the future.4.A heterostructured MIL-125/Ag/g-C3N4 nanocomposite was implemented as an efficient bifunctional visible-light response catalyst for the photoreduction of nitrocompounds and the oxidation of alcohols.The structure,morphology and optical properties of heterostructured MIL-125/Ag/g-C3N4 nanocomposite have been thoroughly characterized by FT-IR,SEM,TEM,XRD,BET,UV-vis DRS and PL analysis.Moreover,when using the MIL-125/Ag/g-C3N4 as photocatalyst,it could obtaine superior conversions for the photoreduction of nitrocompounds and oxidation of the alcohols.It is demonstrated that Ag nanoparticles?NPs?were photodeposited on the surface of g-C3N4 and MIL-125 to increase visible-light absorption via the surface plasmon resonance.As an electron-conduction bridge in the interface between MIL-125 and g-C3N4,Ag NPs could facilitate the direct migration of photoinduced electrons from g-C3N4 to MIL-125 and retard the recombination of electron-holes.Therefore,the MIL-125/Ag/g-C3N4 shows highest photocatalytic activity among MIL-125,g-C3N4,MIL-125/Ag and MIL-125/g-C3N4.It is concluded that MIL-125/Ag/g-C3N4 would be a promising visible light photocatalyst in the field of selective organic transformations. |
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