电化学氧泵的研究

发布时间：2018-03-08 10:04

  本文选题：电化学氧泵　切入点：鸡蛋黄　出处：《天津大学》2015年硕士论文　论文类型：学位论文

【摘要】：电化学氧泵(EOP)是一种基于空气电极的电化学制氧装置,可以在电位差的驱动下将O_2从低浓度混合气中分离出来。但目前基于质子交换膜电解池的EOP动力学缓慢且催化剂价格昂贵,而基于碱性电解液体系的EOP存在漏液、溶液碳酸化所导致的的电解质结晶析出以及电解液浪费等诸多问题。本文从基于生物质的双功能氧电极催化剂、高强度水凝胶电解质膜和不同催化剂体系的电化学氧泵性能等方面对电化学氧泵进行了研究。以鸡蛋黄为前驱体,经一步热解法在熔融盐介质中制备了杂原子掺杂碳(HDC)材料电催化剂,其中原位掺杂的N含量最高可达5.89 wt.%,并掺杂有少量的P和S,XPS测试结果表明N原子多以Graphitic-N和Pyridinic-N形式掺杂到碳骨架中。使用循环伏安法、线性扫描伏安法以及计时电流法等测试方法在旋转圆盘电极上对HDC催化剂电催化性能进行了表征,结果表明800℃下热解制备的HDC催化剂的氧还原反应催化活性与商品Pt/C催化剂相当,而析氧反应催化活性和稳定性则优于Pt/C催化剂。向蛋黄前体中加入六水合氯化钴可使制得的HDC由疏松的不规则片层状结构变为含有大量不规则泡孔的海绵状结构,并在孔内沉积Co_2P纳米颗粒。这种独特的催化剂结构有效地提高了其ORR催化活性和OER稳定性。以丙烯酰胺和聚乙烯醇为交联前体,采用预混式两步交联法制备了一种具有较高抗拉强度的聚丙烯酰胺/聚乙烯醇(PAM/PVA)双网络水凝胶。采用该方法可使两级网络前体在交联成型前预混均匀,提高水凝胶的结构均一性。以该方法制得的水凝胶具有极疏松的互通式孔洞结构,弹性模量可达50 kPa以上,拉伸断裂应力可达113.4 kPa。对该水凝胶进行碱掺杂,制得了电导率高达10~(-2) S·cm~(-1)数量级的碱掺杂水凝胶电解质膜,电化学稳定窗口可达2.0 V左右,有望作为固体电解质膜应用于燃料电池和电化学氧泵等电化学装置中。分别以贵金属催化剂(20 wt.%Pt/C为阴极催化剂,铱黑为阳极催化剂)、自制的HDC催化剂和自制的Co_2P-HDC催化剂为电极催化剂,进行了电化学制氧的研究,所用电解质为自制的碱掺杂PAM/PVA双网络水凝胶电解质膜。其中以Co_2P-HDC作为电极催化剂的电解起始电压为0.587 V,在1.0 V电解电压下运行1 h后电流保持率为62%,在50 mA·cm~(-2)的低电流密度下运行时的电压升高速率仅为2.66 mV·h~(-1),表现出比贵金属催化剂氧泵更优的性能。
[Abstract]:Electrochemical oxygen pump (EOPP) is an electrochemical oxygen generator based on air electrode. O _ s _ 2 can be separated from low concentration mixture driven by potential difference, but the kinetics of EOP based on proton exchange membrane electrolysis cell is slow and the cost of catalyst is expensive, while EOP based on alkaline electrolyte system has leakage. In this paper, the bifunctional oxygen electrode catalyst based on biomass is used to solve the problems of electrolyte crystallization and electrolyte waste caused by carbonation of solution. The electrochemical oxygen pump properties of high strength hydrogel electrolyte membrane and different catalyst systems were studied. In this paper, a one-step pyrolysis method was used to prepare hetero-atom doped carbon-doped HDC-based electrocatalysts in molten salt medium. The content of N in situ doping can reach 5.89 wt.In addition, a small amount of P and Schi-XPS results show that N atoms are mostly doped into the carbon skeleton in the form of Graphitic-N and Pyridinic-N, and cyclic voltammetry is used. The electrocatalytic properties of HDC catalysts were characterized by linear scanning voltammetry and chronoamperometric method on rotating disk electrodes. The results show that the catalytic activity of HDC catalyst prepared by pyrolysis at 800 鈩，

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