Controllable Preparation And Oxygen Electrode Electrocatalytic Performance Of Carbon Fiber Supported Layered Double Hydroxides Material

With the rapid development of economy, there are various kinds of problems of environmental pollution and energy crisis caused by the fossil fuels consumption. The hydrogen energy has the advantages of high combustion value, low density and product water, which has a great potential for development of renewable energy. Therefore, the sustainable energy conversion and storage of hydrogen energy is the focus of current research. Along with the rapid development of electronic information technology, computers, mobile phones and microwave ovens not only richen people's lives but also bring intangible electromagnetic pollution.Besides, it is of great importance to explore novel stealth technologies to improve the survival of war equipment on the battlefield in the modern war.Carbon fiber has excellent application prospects in the field of new energy and information because of its excellent conductivity and high dielectric constant, as one kind of the promising electrocatalyst supporters and absorbing materials. At present, layered double hydroxides ?LDHs?,which are mainly composed of Co, Ni and Fe as the main transition metals, exhibit good electrocatalytic activity and stability of the oxygen electrode, and are used as the precursor to produce spinel type ferrite magnetic materials.In this work, we prepared a series of LDHs films with different interlayer distance in the interlayer and different chemical composition in the host sheet on carbon fiber by urea-assisted hydrothermal method,carefully investigated the corresponding electrocatalytic performance towards oxygen evolution reaction ?OER? and oxygen reduction reaction?ORR?, and revealed the potential relationship between the structure and the property. Besides, we further prepared spinel type ferrite by calcination of LDHs precursor under optimized conditions. The main contents were as follows:1. A series of LDHs film with the different thickness in the range of 0.85-1.8 ?m were prepared by adjusting the amount of the structure directing agent and the precipitating agent in the synthesis system. Both of the directing agent and the precipitating agent played a key role in the growth of LDHs film on CF. For example, the increase of the precipiting agent caused the higher thickness of LDHs film and larger sheet size was increased, which favored to produce larger pore of LDHs film. Also, the increase of the structure directing agent resulted in the higher thickness and larger pore size of the films.2. A series of Ni₂Fe-LDHs/CFP composites with different interlayer distance from 0.74 nm to 2.49 nm were prepared by adjusting the amout of interlayer guest SDS, where LDHs was used as the electrocatalytic active component and carbon fiber paper was as the conductive substrate.The results showed that the LDHs/CFP with the interlayer spacing of 2.49 nm had an oxygen evolution potential of 289 mV at the current density of 10 mA/cm2 and a Tafel slope of 39 mV/dec, which was superior to the noble metal IrO2 catalyst.3. A series of Ni₂Fe-, Co₂Fe- and NiCoFe-LDHsCFP with different chemical compositions in the host sheet were prepared by urea-assised hydrothermal method, and the relationship between the electrocatalytic performance ?OER and ORR? and LDHs/CFP structure was investigated.Among the investigated chemical compositions, NiCoFe-LDHs/CFP demonstrated the best eletrocatalytic activity.4. A series of carbon fiber supported spinel ferrite materials were prepared under the optimized the growth conditions of the LDHs/CF precursors. The different morphology of the spinel ferrite films on carbon fiber were obtained and the corresponding properties were attempated to investigate.