The Preparation And Characterization Of Advanced Functional 2D Materials And Their Applications On Energy Conversion

In the past two or three decades, the global demand of fossil fuels increased quikly due to the rapid development of modern industry, leading to the energy and environmental problems more and more seriously. Therefore, seeking alternatives to fossil fuels becomes a major problem in the world.Due to the excellent physical and chemical properties, two-dimensional materials become hot materials in research areas such as energy storage, chemical catalysis, and optoelectronic devices.By simulating photosynthesis, sustainable energy could achieve reusable by photoelectric conversion technology, which transmits solar energy into electrical energy. Currently, among all the photoelectric conversion materials, the solar energy conversion technology based on inorganic materials has been relatively mature. Because of requiring highly purity materials, high manufacturing costs and causing liquid wastes, this technology has great difficulties on mass production. For these reasons, the development of new, high efficiency, low cost, environmental functionalization organic photovoltaic material is considered to be one of the most promising solutions from the view point of basic research.Another research focusing on the renewable energy is carbon resource. CO2 is a very important part of the earth’s carbon cycle. CO2 mainly comes from organic matter decay, animals and plants because of burning and breathing in nature. Photosynthesis of plants will take CO2 into the carbon cycle again, which provides energy for the survival of the whole biologic chain. Because of the human activities, especially large combustion of fossil fuels, the balance of carbon in nature damaged seriously. So how to design and develop new catalytic materials to decrease CO2 emissions and reuse CO2 to generate liquid fuels becomes the forefront of basic research.The main content of this thesis is using advanced functional materials to achieve renewable energy in nature into energy that can be used directly in human life, achieving environmental friendly. Main works are as follows:1. Designed and synthesized small molecular advanced functional two-dimensional conjugated organic photoelectric materials based on cheap dye indigo, achieving organic photovoltaic based on small molecular cheap indigo. Small molecules are more soluble and controllable. The two-dimensional molecular control strategy implemented in organic small molecules could achieve absorption from 300 nm to 750 nm in the full spectrum of visible light range, which is very difficult to achieve in small molecules. This design strategy for the organic photoelectric materials provides a new thought on methodology.2. Synthesized an advanced functional two-dimensional π electronic system of electroactive materials-directional covalent organic framework thin film. Taking COF-LZU1 as an example, different factors on the control of thin film growth process were studied, including film crystallinity in different growth times, monomer concentrations, comparison of different bases, using wide angle X-ray scattering grazing incidence (GIWAXS) to look into the structure inside the COFs. This is the first time revealing the growth process of COFs thin film. The electrical conductivity of the material can be improved by chemical doping. This offers a foundation of material application in organic photoelectric conversion.3. Electrocatalysis reduction of CO2 into liquid fuels using advanced functional materials-nitrogen doped two-dimensional graphene (N-graphene). This strategy will reduce the emission of CO2 in the atmosphere, and catalytic CO2 to available energy at the same time. The first example of metal-free nitrogen-doped graphene-based materials for electrochemical reduction of CO2 to formate was reported. The synthesized catalysts are highly active and stable in electrocatalytic reduction of CO2 to formate in aqueous electrolyte. The novel catalyst outperforms the prevalent noble metal electrodes, nanostructured metals and state-of-the-art metal-free electrocatalysts by achieving comparable selectivity of formate but with a much lower overpotential.