基于钴元素化合物的制备及其在全电解水中的催化应用

发布时间：2018-04-20 08:45

本文选题：电催化剂 + 析氧反应　；参考：《西华师范大学》2017年硕士论文

【摘要】：对能源需求的增加以及化石燃料的枯竭加快了低碳、可再生、清洁能源的寻找。氢气,由于其出色的能量密度和高效的转换率被认为是最理想的选择。在工业上氢气通常主要是由煤、石油和天然气制得,但是随之产生的副产品:一氧化碳和二氧化碳,其中二氧化碳将会造成全球变暖。电解水是产生高效、清洁的氢能源的有效化学途径。贵金属化合物显示出最高的催化性能(IrO2/RuO2用于OER,Pt用于HER),但他们材料本身的高成本和稀缺性限制了其广泛的应用。双功能催化剂的使用可以简化制备过程从而降低成本。因此,寻找对OER和HER都有效的双功能纳米催化剂变得非常重要。本论文主要研究了基于钴元素的纳米材料的制备及在全电解水方面的应用。主要包括以下内容:1.通过一步法合成了钛网上自支撑的无定形硒化钴纳米粒子(a-CoSe/Ti)。实验结果表明,所制备的硒化钴纳米粒子均匀分布在钛网上,且厚度达到了10微米。在碱性条件下,该材料表现出较高的析氧和析氢催化活性并展现出很强的稳定性。在电流密度达到10 m A cm-2的时候,对于析氧反应硒化钴纳米粒子电极仅需292mV的过电位,析氢反应仅需121 mV。同时用a-CoSe/Ti在碱性条件下作为双电极体系电解水,电流密度达到10 mA cm-2的时候需要电压1.65 V。这项工作对降低全电解水的应用成本提供了新思路。2.我们第一次报导了在钛片上通过电沉积一步法制备钴掺杂的二硒化镍纳米粒子(Co0.13Ni0.87Se2/Ti)并探究其在碱性电解液中的催化性能。Co0.13Ni0.87Se2/Ti是一个高效、低成本且很稳定的析氧和析氢三维电极。在1.0 M KOH中,Co0.13Ni0.87Se2/Ti在析氢反应中需要64 m V过电势达到电流密度10 mA cm-2,析氧反应中也仅仅只需要320 mV过电势达到电流密度100 mA cm-2。用Co0.13Ni0.87Se2/Ti作为阳极和阴极的两电极碱性水电解,达到电流密度10 mA cm-2仅需要电压1.62 V。3.通过密度泛函理论得知锌元素掺杂磷化钴后其催化性能有很大提升。我们首次报导了通过两步法在钛网基底上合成了锌掺杂的磷化钴纳米片(Zn0.08Co0.92P/TM)。把该材料用作酸性和碱性中的三维产氢催化剂时,Zn0.08Co0.92P/TM在酸性和碱性中表现出高效持久的析氢活性。在碱性两电极体系中,为进一步降低反应所需的过电势,我们向电解液中添加了一定浓度的尿素,实验结果表明在1.0 M KOH与0.5 M尿素的混合液中两电极电解达到10 mA cm-2的电流密度仅需电压1.38 V,比碱性两电极电解水减少了0.26 V。
[Abstract]:Increased demand for energy and depletion of fossil fuels have accelerated the search for low-carbon, renewable, and clean energy. Hydrogen, due to its excellent energy density and high conversion rate, is considered to be the ideal choice. In industry hydrogen is usually made mainly from coal, oil and natural gas, but the byproducts are carbon monoxide and carbon dioxide, which will cause global warming. Electrolytic water is an effective chemical pathway for producing efficient, clean hydrogen energy. The noble metal compounds show the highest catalytic performance. IRO _ 2 / RuO _ 2 is used in the peroxidase, but their high cost and scarcity limit their wide application. The use of bifunctional catalysts can simplify the preparation process and thus reduce the cost. Therefore, it is very important to find two functional nano catalysts that are effective for both OER and HER. In this paper, the preparation and application of cobalt-based nanomaterials in electrolytic water were studied. Mainly include the following content: 1. The amorphous cobalt selenide nanocrystalline a-CoSe-TiN was synthesized by one-step method. The experimental results show that the prepared cobalt selenide nanoparticles are uniformly distributed on the titanium network and the thickness is up to 10 microns. Under alkaline conditions, the material exhibited high catalytic activity of oxygen evolution and hydrogen evolution and showed strong stability. When the current density is up to 10 Ma cm-2, only 292mV overpotential is required for oxygen evolution reaction of cobalt selenide nanoparticles electrode and 121mV for hydrogen evolution reaction. At the same time, when a-CoSe/Ti is used as electrolytic water with two electrodes in alkaline condition, the voltage is 1.65 V when the current density reaches 10 Ma cm-2. This work provides a new way to reduce the application cost of the whole electrolytic water. We report for the first time the preparation of cobalt doped nickel diselenide nanoparticles Co0.13Ni0.87Se2 / Ti on titanium wafer by one step electrodeposition method and investigate its catalytic performance in alkaline electrolyte. Co0.13Ni0.87Se2 / Ti is a highly efficient, low-cost and stable three-dimensional electrode for oxygen evolution and hydrogen evolution. Co0.13Ni0.87Se2 / Ti needs 64 MV overpotential to reach current density 10 Ma cm-2 in 1.0 M KOH, and only 320 MV overpotential to 100mA cm-2 in oxygen evolution reaction. Using Co0.13Ni0.87Se2/Ti as anode and cathode for alkaline water electrolysis of two electrodes, only 1.62 V. 3 voltage is required to achieve current density of 10 Ma cm-2. Through density functional theory, it was found that the catalytic activity of zinc doped cobalt phosphide was greatly improved. We report for the first time that zinc doped cobalt phosphide nanocrystals Zn0.08Co0.92P / TMN have been synthesized on titanium mesh substrates by two-step method. The Zn0.08Co0.92P / TM exhibits high and persistent hydrogen evolution activity in acid and alkalinity when it is used as a three-dimensional catalyst for hydrogen production in acidic and alkaline systems. In the alkaline two-electrode system, in order to further reduce the overpotential required for the reaction, we added a certain concentration of urea to the electrolyte. The experimental results show that the current density of 10 Ma cm-2 in the mixture solution of 1.0 M KOH and 0.5 M urea only requires a voltage of 1.38 V, which is 0.26 V less than that of alkaline two-electrode electrolytic water.
【学位授予单位】：西华师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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