碳负载镍金属催化剂的制备及乙醇氧化性能研究

发布时间：2018-03-08 18:37

本文选题：镍纳米颗粒　切入点：镍纳米棒　出处：《天津工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：直接乙醇燃料电池(DEFC)由于其燃料使用安全、来源丰富、价格低廉、易携带和储存等独特的优越性,越来越引起研究者的关注,高效低成本催化剂的开发是直接乙醇燃料电池商业化必须要解决的问题之一。本论文主要采用非贵金属制备了氮掺杂碳负载镍金属催化剂,系统研究了不同碳源、镍源、原料配比、氮掺杂的情况下对催化剂性能的影响,设计了具有形貌和尺寸可控的碳载镍纳米材料,并考察了所制备材料对乙醇的电催化性能。1.通过一步合成法制备了氮掺杂碳包覆纳米镍(NiNC)颗粒催化剂(葡萄糖为碳源,乙酸镍为镍源,尿素为氮源)。镍纳米粒子的大小可以通过调节原材料的质量比来调控。葡萄糖热处理后变为多孔活性炭。添加尿素产生了丰富的氮官能团。在制备的所有的催化剂中,NiNC-4催化剂镍颗粒平均尺寸最小(2.02 nm),BET比表面积最大(400.7m2g-1)以及含氮总量(7.21 at%)最多。多孔碳结构,小的镍纳米尺寸和丰富的官能团使NiNC-4催化剂具有良好的电催化性能。在0.1 mol L-1 NaOH+1 mol L-1 C2H5OH溶液中,NiNC-4催化剂的峰电流密度高达327mAcm-2,并且表现出良好的长期循环稳定性,循环500圈以后,峰电流密度仍然能保持89%。然后移入新的电解液重复测试,峰电流密度还能达到初始电流密度的96.8%。NiNC-4催化剂优良的电催化性能,来源于多孔碳包覆,丰富的含氮基团和小尺寸镍纳米粒子的协同作用。2.通过一步合成法制备了尺寸可控的镍纳米棒(蔗糖为碳源,氯化镍为镍源,尿素为氮源)。讨论了不同镍前驱体和不同碳源对纳米镍的微观形貌影响,表明蔗糖和氯离子是形成镍纳米棒的关键因素。镍纳米棒的大小可以通过反应物的比例来控制,并且氮掺杂可以提高乙醇电催化氧化性能。在制备的催化剂中,NiNC'-3催化剂性能最好。相比于NiNC'-l催化剂,NiNC'-3催化剂的电流密度(47.5 mA cm-2)和应速率常数分别是它的5倍和16倍。此外,循环1500圈以后,NiNC'-3催化剂的电流密度仍能保持80.7%,表明NiNC'-3催化剂有良好的循环稳定性。NiNC'-3催化剂对乙醇高的电催化性能可以归因于均匀的镍纳米棒以及优异的导电性和稳定的碳载体。
[Abstract]:Direct ethanol fuel cell (DEFC) has attracted more and more attention due to its unique advantages such as safe use of fuel, abundant sources, low price, easy to carry and store. The development of high efficiency and low cost catalyst is one of the problems that must be solved in the commercialization of direct ethanol fuel cell. In this thesis, the nitrogen-doped carbon-supported nickel metal catalyst was prepared and the different carbon and nickel sources were systematically studied. The effects of the ratio of raw materials and nitrogen doping on the performance of the catalyst were investigated. The carbon supported nickel nanomaterials with controllable morphology and size were designed. The electrocatalytic properties of the prepared materials for ethanol were investigated. 1. The nitrogen-doped carbon coated nano-Ni Ni NNCC catalyst (glucose as carbon source, nickel acetate as nickel source) was prepared by one step synthesis method. Urea is nitrogen source. The size of nickel nanoparticles can be adjusted by adjusting the mass ratio of raw materials. After glucose heat treatment, it becomes porous activated carbon. The addition of urea produces rich nitrogen functional groups. The average size of nickel particles in NiNC-4 catalyst was the smallest (2.02 nm) and the maximum specific surface area of BET was 400.7m2g-1) and the total nitrogen content was 7.21 at.1). In 0.1 mol L-1 NaOH 1 mol L -1 C 2H 5OH solution, the peak current density of NiNC-4 catalyst was 327mAcm-2 and showed good long-term cycling stability. After 500 cycles, the peak current density can still be kept 89%. Then the peak current density can reach 96.8% of the initial current density. NiNC-4 catalyst has excellent electrocatalytic performance, and the peak current density can be obtained from the porous carbon coating. The synergistic effect of rich nitrogen-containing groups and small nickel nanoparticles. (2) Nickel nanorods with controlled size (sucrose as carbon source, nickel chloride as nickel source, nickel chloride as nickel source) were prepared by one-step synthesis method. The effects of different nickel precursors and carbon sources on the microstructure of nickel nanocrystalline were discussed. The results show that sucrose and chloride ions are the key factors in the formation of nickel nanorods. The size of nickel nanorods can be controlled by the ratio of reactants. Nitrogen doping can improve the performance of ethanol electrocatalytic oxidation. The catalytic activity of NiNC- 3 is the best in the prepared catalyst. Compared with NiNC'-l catalyst, the current density of NiNC- 3 catalyst is 47.5 Ma cm-2) and the rate constant is 16 times higher than that of NiNC- 3 catalyst. After 1500 cycles, the current density of the catalyst can be maintained at 80.7, which indicates that the NiNC'-3 catalyst has good cyclic stability. The high electrocatalytic performance of the catalyst for ethanol can be attributed to the uniform nickel nanorods, excellent conductivity and stable carbon support.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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