Study On Preparation,Characterization And Photocatalytic Property Of Several Organic-Inorganic Composite Materials

With the development of society and the enhancement of people's awareness of environmental protection,people are gradually aware of the current tight energy shortage and environmental pollution problems.Photocatalysis technology is an environment-friendly technology,which can convert abundant natural solar energy into chemical energy for production and life,to promote the photocatalytic water splitting,photodegradation of organic pollutants,photocatalytic synthesis of organic chemicals,etc.Photocatalytic technology plays a pivotal role in effectively solving the current tight energy shortage and serious environmental pollution problems.People are committed to developing efficient and clean photocatalytic materials,and consequently many types of photocatalytic materials come into people's visionIn a wide range of photocatalytic material systems,organic-inorganic composite materials can collect organic components,inorganic components and the interaction between their interfaces.Due to its unique structural components and excellent photocatalytic performance,it is generally considered as a class of photocatalytic materials with potential application value,which has become the focus of attention and the key of research.More and more organic-inorganic composite materials have been developed and researched,which has promoted the development of photocatalytic technology.It is precisely because of the good designability of the organic components that the properties and functions of the materials can be changed by functional group substitution,and then composite with inorganic components,it is easier to obtain the target materials that meet the actual needs of people.Organic-inorganic composite materials can exert the synergistic or complementary effects of a single component,which also have excellent properties that cannot be matched by single organic component and single inorganic component.Therefore,it is very necessary to study the application of organic-inorganic composite materials in the field of photocatalysis.As a special kind of organic-inorganic composite porous material,metal-organic f ramework materials(MOFs)have attracted close attention and enthusiasm for research.MOFs are periodic frame materials that are alternately connected to each other with inorganic metal ions as the connection nodes and organic ligands as the linker.The inorganic and organic components are formed by "self-assembly" coordination.With the continuous exploration of MOFs materials,it is found that MOFs materials generally have properties and functions that cannot be surpassed by single components,such as large specific surface area,ordered channels,and designable structure.Moreover,as photocatalyst,MOFs materials can collect photosensitizer,catalytic center and skeleton structure,and have high efficiency in the field of photocatalysis.At present,there are few researches on MOFs materials constructed by main group metal ions,so it is of great research value to explore new type of MOFs photocatalytic materials.In the field of photocatalysis,organic-inorganic composite materials are highly favored because of their excellent properties and efficient photocatalytic activity.In this paper,we have studied three organic-inorganic composite materials.The main research contents and important conclusions are as follows:In the first chapter,we first briefly summarized the basic principles,current problems,and photocatalytic materials of semiconductor photocatalysis.Subsequently,the composition,interfacial effects,and preparation methods of organic-inorganic composite materials are described.We also analyze the advantages of organic-inorganic composite materials in the field of photocatalysis,and outline the applications of several organic-inorganic composite photocatalytic materials.Then,we briefly introduced a special organic-inorganic composite porous material,namely Metal-organic framework materials(MOFs),including the basic components of MOFs,preparation methods,and several effective MOFs applied in the field of photocatalysis.Finally,the significance and research content of this paper are presented.In the second chapter,we studied the preparation of copper ions-modified graphite phase carbon nitride(C3N4)composites and its photocatalytic properties and mechanism for hydrogen production.Powder samples of CU-C3N4 were prepared by a simple ultrasonic treatment method,and basic characterizations such as XRD and XPS were performed,indicating that the samples have high purity and retains the layered structure of C3N4 materials.The photocatalytic hydrogen production experiments show that Cu-C3N4 has higher photocatalytic hydrogen production activity than C3N4.In order to further clarify the effect of copper ions modification on C3N4 and different metal complexation sites on the hydrogen production activity of the material,the hydroxylated C3N4 material was modified with copper ion to obtain Cu-OH-C3N4 powder.The experiment also proved the conclusion that copper ions modification promoted photocatalytic hydrogen.Then the DRS and PL tests of C3N4,Cu-C3N4,OH-C3N4 and Cu-OH-C3N4 were carried out to study their photophysical properties.Finally,based on the analysis of characterization data,Cu-N coordination in Cu-C3N4 and Cu-O coordination in Cu-OH-C3N4,we proposed a possible mechanism of photocatalytic hydrogen production in Cu-C3N4 and Cu-OH-C3N4.The presence of copper sites can promote the migration and separation of photogenerated carriers,so as to enhance the ability of the materials to perform photocatalytic hydrogen production.In the third chapter,we studied the preparation,the photoelectric performance,the photocatalytic degradation of organic dye RhB and the active oxygen species in the degradation process for Keggin Phosphotungstic acid(HPW)modified Tetracarboxyphenylporphyrin(TCPP)composites.We prepared composites(HPW-TCPP)by simple mechanical stirring at room temperature,and carried out basic characterization such as XRD,FT-IR,and DRS.We believe that HPW and TCPP molecules have a strong electronic coupling interaction.The obtained HPW-TCPP retains both the TCPP structure and the HPW structure.The photoelectric performance test shows that HPW-TCPP has a higher photocurrent response than TCPP,and both materials have good stability.Through photocatalytic degradation of RhB,HPW-TCPP has more efficient degradation ability under the condition of an appropriate amount of 30%H2O2 solutions.Finally,the reactive oxygen species in the photocatalytic degradation process were investigated.And experiments showed that·OH and ·O2-existed in the photocatalytic degradation process,but ·O2-was the major reactive oxygen species.It is of great significance to study porphyrin organic-inorganic composite photocatalysts.In the fourth chapter,we report the preparation,characterization,and CO2 adsorption of a special organic-inorganic composite porous material,a novel bismuth-based MOFs material(Bi-BDC-NH2).Firstly,according to the literature,a kind of MOFs material Bi-PYDC with 3,5-pyridyl dicarboxylic acid(3,5-H2PYDC)as ligand was prepared by hydrothermal method.Then,due to the properties of ion exchange of Bi-PYDC,the MOFs material Bi-BDC-NH2 was prepared by solvothermal method with Bi-PYDC as precursor and 2-aminoterephthalic acid(BDC-NH2)as organic ligands We described the structure of Bi-BDC-NH2 in detail,and measured its specific surface area and thermal stability by BET,TG/DTA,etc.Finally,we performed a CO2 adsorption activity test and found that Bi-BDC-NH2 has a higher CO2 adsorption capacity than Bi-PYDC,and explained a possible reason,that is,the organic bridging ligand of Bi-BDC-NH2 is 2-aminoterephthalic acid anions,which is due to the presence of-NH2,it can be used as basic sites to better adsorb acidic molecules CO2.In the fifth chapter,it is the summary and prospect of this paper.We mainly summarized the work mentioned in this paper and the conclusions,and listed the innovations of this paper.Of course,we also recognized the existing problems in the work,and finally looked forward to further research in the future.In general,the combination of inorganic and organic components is the main research content in this paper.The preparation,characterization,and photocatalytic activity of organic-inorganic composites are studied,which have an important impact on the acceleration of the development of photocatalytic technology.