| Over the past few years, the synthesis, characterization and catalytic applications of nanostructured metal and metal oxide based materials have been the subject of extensive research. Numerous methods have been developed to prepare these materials with various sizes, shapes and morphologies, for example, sol-gel method and hydrothermal/solvothermal methods. Since MOF scaffolds contain abundant metal ions, it is an alternative to use MOFs as templates and precursors to get nanostructured metal-based materials under suitable calcination conditions. A rich variety of metal ions that are used in MOFs provides abundant opportunities to prepare different kinds of nanostructured metal-based materials from MOFs. It is found that MOFs could be used as templates and precursors to prepare metals, metal oxides, metal sulfides as well as other nanostructured metal-based materials. The obtained materials have been widely used in the catalysis, energy and environmental areas. Herein, Cu-BTC and Fe3[Co(CN)6]2 were used as precursors to fabricate metal/metal oxide/carbon and metal/carbon materials, which were further used as catalysts for CO oxidation reaction and the reduction of 4-NP, respectively. The concerns of this dissertation include following aspects:1. Metal/metal oxide/carbon:Heterogeneous catalysts facilitate various chemical reactions through changing its surface charge density. However, the easy agglomeration of nano-sized heterogeneous catalysts and either expensive techniques or a multistep method involved in the fabrication of such hybrid structures makes developing low-cost, agglomeration-free heterogeneous catalysts highly desirable. Copper and its oxides have long been studied as catalysts towards CO oxidation while less attention has been paid on the catalytic activity of Cu/Cu2O, Cu/CuO interface because the interface tends to form core-shell structures in oxygen atmospheres, making the interface buried inside oxide layers. Herein, we designed Cu/CU2O nanojunctions wrapped and supported by porous carbon through direct annealing of a Cu-based metal-organic framework (Cu-BTC) in N2, followed by testing its catalytic activity towards CO oxidation. Besides, CO oxidation reactions over Cu, Cu2O, CuO and interface of Cu/CU2O and Cu/CuO are studied via density functional theory (DFT) simulation. The catalyst shows a complete CO conversion temperature (T100) of 155 ℃ under both 1 vol.% and 5 vol.% CO. In addition, it maintains a long-term durability even after 40h under 1 vol.% CO. Our DFT calculation demonstrates that the significant increase in electron density on Cu/CU2O, Cu/CuO interface plays a pivotal role in enhancement of CO oxidation.2. Metal/carbon:As we know, the graphene-encapsulated metal catalyst, on which O2 is readily activated by the electrons transferred from the metal to the surface, has been demonstrated to be a promising strategy to produce robust non-precious-metal electrocatalysts. Herein, FeCo nanocrystals with nitrogen-doped graphene layers were obtained by thermal decomposition of Fe?[Co(CN)6]2 spheres. The synthesized FeCo nanocrystals show a strong magnetic response. When employed as a catalyst for the reduction of 4-NP, the FeCo nanocrystals not only exhibit high catalytic activity and stability due to their structural features, but also can be separated easily with the help of a magnet. Besides, the kapp value is comparable to that of some precious-metal catalysts for the reduction of 4-NP. |
PDF Full Text Request