| Layered perovskites have aroused extensive research interest owing to their particular structure and outstanding electrical properties and photocatalysis. Using topochemical manipulations, a lot of layered perovskites can be processed into novel materials, including intercalation compounds, pillered compounds, organic-inorganic hybrids, two dimensional exfoliated nanosheets and nanoscrolled materials, and their assembled namomaterials. The objective of the dissertation is to modify the interlayer surface of layered perovskites with organic species, carbon and noble metals by topochemical reaction strategies, which lead to formation of some new materials. The main parts of the research are as follows:1. Under solvothermal (2-butanone) conditions, n-decoxyl derivative of HLaNb2O7, a two-layer Dion-Jacobson type layered perovskite, has been successfully reacted with a-D-glucopyronose by alcohol-exchange-type reaction. As a consequent result, a novel organic-inorganic hybrid material, that is a-D-glucopyronose intercalation compound (Glucose-HLaNb2O7), has been produced. Many experiments were carried out for an optimized preparation condition, whose results revealed that if the reaction temperature is too high, glucose will be carbonized, and if too low, the reaction cannot proceed.2. Glucose-HLaNb2O7has been pyrolyzed to form the other new carbon intercalated compound (Carbon-HLaNb2O7) at300℃under flow Ar atmosphere. If the temperature is too high, the glucose molecules in the interlayer will decompose into some little organic molecules and CO2, which results in no carbon depositing in the interlayer space. Carbon-HLaNb2O7can absorb all visible light, and its band gap energy is only about0.65eV, which is smaller than those of all reported Dion-Jacobson type layered perovskites. As a conclusion, the study provided a novel method for intercalating carbon into the interlayer space to synthesize new carbon intercalated compounds, that is, carbon was used as guest species and a layered compound as host unit.3. Using Glucose-HLaNb2O7as a precursor,[Ag(NH3)2]+ion solution oxidized the free glucose molecules within the interlayer space due to the hydrolysis of Glucose-HLaNb2O7, which resulted in the layer-by-layer assembly of HLaNb2O7nanosheets and Ag nanoparticles/clusters to form a novel3D metal/semiconductor hybrid material, Ag/HLaNb2O7. It is a very simple and convenient method for layer-by-layer assembly. Ag nanoparticles were seated in the interspaces between HLaNb2O7nanosheets and Ag nanoclusters were mainly located in the interlayer space of HLaNb2O7. Ag/HLaNb2O7is a mecoporous material, which is not derived from the interlayer space of HLaNb2O7but the interspaces between HLaNb2O7nanosheets. Based on catalytic results, Ag/HLaNb2O7is an excellent catalyst, even better than pure noble metal Ag. So it is a very promising new catalyst.4. Using Glucose-HLaNb2O7as a precursor, H2PtCl6aqueous solution oxidized the free glucose molecules within the interlayer space due to the hydrolysis of Glucose-HLaNb2O7. As a result, bivalent Pt nanoparticles were deposited in the interlayer space of HLaNb2O7to form the other novel3D semiconductor hybrid material, Pt/HLaNb2O7. The intercalation of bivalent Pt nanoparticles will expose more active sites and the absorption band extends to visible light, which makes them to be a promising material in energy field.5. Under solvothermal conditions, the intercalation of n-butylamine and the grafting reaction of n-propanol in the interlayer space of HLaNb2O7have been investigated. HLaNb2O7is a two-layer Dion-Jacobson type layered perovskite. The results show that n-butylamine can be inserted into the interlayer space to form pure intercalation compound (n-butylamine/HLaTa2O7) at80℃for three days. Using n-butylamine/HLaTa2O7as a precursor, the grafting reaction of n-propanol both failed whether existing water or not. In other word, n-propanol cannot be grafted into the interlayer space of HLaTa2O7under these conditions.6. Under solvothermal conditions, the grafting reactions of various alcohols in the interlayer space of HCa2Nb3O10have been studied. HCa2Nb3O10is a three-layer Dion-Jacobson type layered perovskite. According to the results, various alcohols can all be grafted into the interlayer space at80℃for three days and form corresponding alkoxy derivatives. Using the n-decoxyl derivative of HCa2Nb3O10as a precursor, the grafting reaction of glucose has been researched. The results reveal that the optimized reaction temperature is80℃. At low temperature, the reaction cannot proceed. However at high temperature, the hydrolysis and carbonization will take place, which is going against grafting reaction. The grafting reaction of glucose is partially carried out, so the experiment system needs deeply research for preparing pure glucose grafted compound of HCa2Nb3O10and its carbon intercalated compound. |
PDF Full Text Request