碳基过渡金属（铁、钴、镍）电催化剂的合成与性能研究

发布时间：2018-03-02 22:37

  本文选题：燃料电池　切入点：金属-空气电池　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：人类进入21世纪以来,世界经济高速发展,能源的消耗日益增大。现今的能源结构中,传统化石燃料依然占据着很大的比重。然而,化石燃料的不可再生性制约着它不能够无限制地被开采下去。而且,化石燃料的过度使用所带来的环境污染问题也日趋严重。因此,发展新能源代替传统化石能源成了当今科学研究的一个热门课题。燃料电池、金属-空气电池、氢能等都是环境友好型能源储存载体,对环境不会造成任何污染。在燃料电池和金属-空气电池的工作中,存在两个关键的反应过程,分别是氧还原和氧析出反应;电解水制氢同样有两个重要的过程,分别是氧析出和氢析出反应。然而,这些过程的发生离不开催化剂的作用,其性能的优劣决定了相应能源器件的性能。因此,寻找合适的电催化剂去驱动这些反应过程具有重要的科学研究意义。本论文研究内容包括设计与制备碳基过渡金属(Fe、Co、Ni)催化剂材料,应用于燃料电池、金属-空气电池的氧还原(ORR)和氧析出(OER)过程研究,以及电解水过程中的析氢(HER)和析氧(OER)反应的研究,系统地揭示了催化剂组成、结构等与ORR/OER/HER电催化性能之间的关系,主要开展了三部分研究工作。研究内容一,利用生物质虾壳为含氮的碳源,与铁(Fe)的前驱体进行混合后,在惰性气氛下,通过高温热解的方式,制备了碳包覆的铁基纳米催化剂粒子复合物。XRD物相分析表明,催化剂粒子主要为金属单质Fe和Fe203。对不同温度下制备的催化剂进行性能评价,结果表明,1000℃下制备催化剂拥有较好的ORR/OER双功能催化活性。在碱性介质中性能测试表明,Fe/Fe2O3@Fe-N-C-1000 ORR反应的起始电位和半波电位分别为-0.04和-0.17 V;在固定转速1600 rpm下,极限电流密度为6.5 mA·cm~(-2),其ORR催化性能可与商业化Pt/C催化剂相媲美;在OER催化过程中,催化剂Fe/Fe2O3@Fe-N-C-1000在10 mA·cm~(-2)时的过电位为460 mV。在酸性介质中,催化剂Fe/Fe203@Fe-N-C-1000具有较好的ORR活性,起始电位和1600 rpm转速下的极限电流密度分别为0.52 V和6.0 mA·cm~(-2),经过20000秒稳定性测试后,其ORR活性依然可以保持在90%以上。进一步,Fe/Fe2O3@Fe-N-C-1000作为空气阴极材料,组装了简易金属锌-空气电池。测试结果表明,电池的开路电压约1.3 V,放电功率能够达到200 mW·cm~(-2)以上,并保持高的电池循环稳定性。研究内容二,以空间三维结构金属有机骨架材料Ni-BTC作为前驱体,在氨气气氛中,进行高温煅烧,得到了 Ni3N/Ni纳米片材料。在碱性介质中,对催化剂进行OER性能测试。结果发现,700℃下制备的催化剂材料(Ni3N/Ni-700)具有优异的OER性能。在电流密度为10 mA·cm--2时,催化剂Ni3N/Ni-700的过电位为290 mV,与商业化的RuO2催化剂基本相当。经过4000次的循环催化测试之后,其催化活性可以保持在90%以上,表明其具有较高的催化稳定性。研究内容三,利用活性炭作为载体,在高温(1000℃)下制备了不同比例的多功能Ni-Co合金催化剂,并进行了自供电电解水产氢性能测试。XRD和STEM表征结果证明了金属Ni和Co是以合金的形式存在,并且被石墨化的碳紧密包裹,有利于增强其催化活性与应用稳定性。在碱性条件下对催化剂材料进行电化学测试,结果表明,所制备的合金催化剂具有ORR/OER/HER三功能催化活性,而且其性能与合金中Ni和Co的比例密切相关。Ni/Co摩尔比为1:3的催化剂(Ni1Co3@C)具有较好的ORR和OER性能,其ORR的起始电位和1600 rpm下的极限电流密度分别为-0.098 V和5.8 mA·cm~(-2),在OER电流密度为10 mA·cm~(-2)时的过电位为470 mV。Ni/Co摩尔比为3:1的催化剂(Ni3Co1@C)具有较好的HER催化活性,电流密度为10 mA·c,-2时的过电位为280 mV。进一步,以NiICo3@C作为空气电极材料,组装了简易金属镁-空气电池。测试发现,电池的开路电压能达到1.7 V,放电功率为30 mW·cm~(-2),并可成功点亮LED灯和带动小功率电风扇。以自制的金属镁-空气电池作为电源,NiICo3@C和Ni3Co1@C分别作为氧电极和氢电极,进行自供电电解水研究。结果表明,3 h反应可收集8 mL氢气,分解水产氢效率为0.044 mL·min-1,而且,产氢和产氧的法拉第效率几乎为100%。
[Abstract]:Since entering the twenty-first Century, the world economy rapid development, energy consumption is increasing. The current energy structure, traditional fossil fuels still occupy a large proportion. However, non renewable fossil fuels can not restrict its unrestricted exploitation. Moreover, the problem of environmental pollution caused by the excessive use of fossil fuels are becoming more and more serious. Therefore, the development of new energy to replace the traditional fossil energy has become a hot research area. Fuel cell, metal air batteries, hydrogen are environment friendly energy storage carrier, will not cause any pollution to the environment. In fuel cells and metal air batteries work, there are two key processes are oxygen reduction and oxygen evolution reaction; water electrolysis also has two important processes, namely oxygen precipitation and hydrogen evolution reaction. However, these The process cannot do without catalyst, its performance determines the performance of the corresponding energy devices. Therefore, to find a suitable catalyst to drive the electric reaction process has important scientific research significance. This thesis studies the design and preparation of carbon based transition metal (Fe, Co, Ni) catalyst materials. The application in fuel cell, metal air battery oxygen reduction (ORR) and oxygen precipitation (OER) process research, and in the process of water electrolysis hydrogen (HER) and oxygen evolution reaction (OER) research systematically reveals the relationship between catalyst composition, structure and Electrocatalytic Performance of ORR/OER/HER. The three part mainly carried out the research work. The research content, the use of biomass of shrimp shell containing nitrogen and carbon source, iron (Fe) precursors were mixed, under an inert atmosphere by high temperature pyrolysis method, preparation of Fe nano catalyst particles coated with carbon compound Compound.XRD phase analysis showed that the catalyst particles are mainly metal elements Fe and Fe203. on the catalyst synthesized at different temperature are evaluated. The results show that the prepared catalyst has better catalytic activity of ORR/OER double function under 1000 DEG C in alkaline medium. Performance tests show that the initial potential Fe/Fe2O3@Fe-N-C-1000 ORR reaction and half wave the potential was -0.04 and -0.17 V; at a fixed speed of 1600 rpm, the limiting current density of 6.5 mA - cm~ (-2), the catalytic performance of ORR can be comparable with commercial Pt/C catalyst in the catalytic process; OER, Fe /Fe2O3@Fe-N-C-1000 catalyst in 10 mA - cm~ (-2) have potential for 460 mV. in acidic medium, Fe/Fe203@Fe-N-C-1000 catalyst has good activity of ORR, limiting current density and initial potential 1600 RPM speed was 0.52 V and 6 mA cm~ (-2), after 20000 seconds after the stability test, ORR The activity remains more than 90%. Further, Fe/Fe2O3@Fe-N-C-1000 as air cathode materials, assembling a simple metal zinc air battery. The test results show that the open circuit voltage of the battery is about 1.3 V, the discharge power can reach 200 mW - cm~ (-2), and keep the battery cycle high stability. The research content of two, with metal the three-dimensional structure of organic matrix material Ni-BTC as precursor, ammonia in the atmosphere, high temperature calcination, obtained Ni3N/Ni nanosheets. In alkaline medium, OER test the performance of the catalyst. The results showed that catalyst material prepared under 700 DEG C (Ni3N/Ni-700) OER has excellent performance. At a current density of 10 mA cm--2, the overpotential of Ni3N/Ni-700 catalyst was 290 mV, and RuO2 commercial catalyst is quite basic. After cyclic catalytic test 4000 times, the catalytic activity can be maintained at 90% On the show that the catalytic stability is higher. The research content of three, the use of activated carbon as a carrier, at high temperature (1000 DEG C) multifunctional Ni-Co alloy catalysts were prepared with different proportion, and since the hydrogen water electrolysis capability of the power supply test.XRD and STEM characterization results show that Ni and Co exist in metal alloy the form and graphitized carbon tightly wrapped, is conducive to enhancing the stability of catalytic activity and application. The electrochemical measurements were performed on the catalyst material under alkaline conditions. The results show that the alloy catalyst prepared is ORR/OER/HER three catalytic activity, and Ni and Co and its performance is closely related to the proportion of alloy.Ni/Co molar ratio 1:3 catalyst (Ni1Co3@C) has better ORR and OER performance, the limiting current density ORR and the initial potential of 1600 RPM were -0.098 V and 5.8 mA cm~ (-2), OER in current density 10 mA - cm~ (-2) potential is 470 mV.Ni/Co when the molar ratio of 3:1 (Ni3Co1@C) HER catalyst has good catalytic activity, the current density is 10 mA - C, -2 potential is 280 mV. further, with NiICo3@C as the air electrode material, simple assembly of magnesium metal - air battery. The test found that the open circuit voltage of the battery can reach 1.7 V, the discharge power was 30 mW - cm~ (-2), and can be successfully lit LED lights and drives a small power electric fan. The magnesium - made air battery as power supply, NiICo3@C and Ni3Co1@C were used as the oxygen electrode and the hydrogen electrode for water electrolysis power supply research 3. The results showed that the h reaction can collect 8 mL hydrogen, hydrogen production efficiency was 0.044 mL - min-1, and hydrogen and oxygen production of Faraday efficiency is nearly 100%.

【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4
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本文编号：1558444