氧还原电化学催化剂研究的最新进展（英文）

发布时间：2018-03-20 05:06

本文选题：氧还原反应　切入点：电催化剂　出处：《催化学报》2017年06期 　论文类型：期刊论文

【摘要】：燃料电池可以在接近室温条件下将氢或烃类中蕴含的巨大化学能通过电化学途径直接转化为清洁、稳定、可持续的电能,因而被视为极有前景的、能够满足日益增长的世界能源需求的终极解决方案之一.在一个典型的氢燃料电池中,氢在正极氧化而氧在负极还原,从动力学角度说,氧还原反应(ORR)比氢氧化反应进行的慢得多.无论是在酸性还是碱性条件下,氧的还原都可以一个四电子过程或是两个双电子过程进行,当然在酸性和碱性环境中反应的机理不同.铂一直是最有效的ORR催化剂,但受到价格昂贵、稳定性差和易中毒等因素的制约,目前非铂催化剂成为越来越引人瞩目的发展方向.本综述试图从分子催化剂、金属纳米材料催化剂、金属氧化物催化剂和新兴的二维材料催化剂等方面,选取近十年来最能代表ORR电化学催化剂方面成就的例子分析其优缺点,并为今后该领域的研究提供一些有益的思路.典型的分子催化剂是卟啉类化合物,当这种四齿的N4配体与过渡金属特别是铁、钴络合时,往往显示出良好的ORR催化性能,多数情况下其中的过渡金属中心、配体和碳支撑体系共同组成催化剂的活性中心.在另一些报道中,邻菲罗啉或是连吡啶型N_2化合物也可以作为配体使用.第四和第五副族的很多金属形成的不同价态的氧化物都具有氧还原活性,比如MnO_x,CoO_x,TiO_x,ZrO_x,IrO_x等.金属氧化物表现出易于修饰,不容易团聚和抗腐蚀等诸多优点,而其良好的ORR性能与表面的缺陷密切相关,因此钙钛矿型氧化物ABO_x也引起人们的广泛关注,人们可以通过调节氧化物的晶型、尺寸和组成来获得更好的催化性能.近年来随着液相合成技术的发展,人们可以制备出理想形状和尺寸的单分散纳米粒子,然后通过旋涂、自组装等手段将其修饰到合适的电极上以获得增强性能的ORR催化剂.通过形状与尺寸调控,或组合成其它复杂的纳米结构,都有可能提高催化活性或是稳定性,因此有关纳米催化剂的研究日趋增多.在此基础上,考虑到石墨烯的可修饰性和良好的电化学性能,纳米材料复合石墨烯所形成的二维或三维结构也可提供很好的氧还原催化性能,而MoS_2代替石墨烯作为支撑物所构成的二维催化剂也是值得注意的研究方向.综上所述,尽管现有的非铂催化剂仍难以完全满足商业化的要求,设计理念和合成方法的快速发展有望在不远的将来解决这一难题.而设计合成可控尺寸、形状、组成和表面形貌的纳米催化剂在很大程度上将加速这一进程.
[Abstract]:Fuel cells can convert the enormous chemical energy contained in hydrogen or hydrocarbons into clean, stable and sustainable electrical energy directly through electrochemical pathways at close to room temperature, and are therefore considered highly promising. One of the ultimate solutions to meet the growing world's energy needs. In a typical hydrogen fuel cell, hydrogen is oxidized at a positive electrode and oxygen is reduced at a negative electrode. The oxygen reduction reaction ORR is much slower than the hydrogen oxidation reaction. Whether in acidic or alkaline conditions, oxygen reduction can take place in one four-electron process or two two-electron processes. Of course, the reaction mechanism is different in acidic and alkaline environment. Platinum has always been the most effective ORR catalyst, but restricted by expensive, poor stability and easy to poisoning, etc. At present, non-platinum catalysts are becoming more and more attractive. In this review, molecular catalysts, metal nanomaterials catalysts, metal oxide catalysts and new two-dimensional materials catalysts are reviewed. The advantages and disadvantages of ORR electrochemical catalysts were analyzed by selecting the most representative examples in recent ten years, and some useful ideas were provided for the future research in this field. The typical molecular catalysts are porphyrin compounds. When the four-toothed N4 ligand complexes with transition metals, especially iron and cobalt, they tend to exhibit good ORR catalytic properties, and in most cases, the transition metal centers, Ligands and carbon support systems together form the active centers of the catalysts. O-phenanthroline or even pyridine-type N _ S _ 2 compounds can also be used as ligands. Oxides in different valence states formed by many metals of the 4th and 5th subgroups have oxygen reductive activities, such as MNO _ XS _ xCoO _ xT _ x _ T _ x _ T _ x _ O _ (x) _ _ _. It is not easy to agglomeration and corrosion resistance and many other advantages, and its good ORR performance and surface defects are closely related, so perovskite oxide ABO_x also attracted widespread attention, people can adjust the crystal form of oxide, In recent years, with the development of liquid-phase synthesis technology, monodisperse nanoparticles of ideal shape and size can be prepared and then spin-coated. The self-assembly method modifies it to the appropriate electrode to obtain the enhanced performance of the ORR catalyst. Through shape and size regulation, or the combination of other complex nanostructures, it is possible to improve the catalytic activity or stability. Therefore, the research on nano-catalysts is increasing. On this basis, considering the modifiability and good electrochemical performance of graphene, The two-dimensional or three-dimensional structure formed by graphene nanocomposites can also provide good catalytic performance for oxygen reduction, and the two-dimensional catalyst composed of MoS_2 instead of graphene as the support is also worthy of attention. Although the existing non-platinum catalysts are still difficult to fully meet the commercial requirements, the rapid development of design concepts and synthesis methods is expected to solve this problem in the near future. Nano-catalysts with composition and surface morphology will accelerate the process to a large extent.
【作者单位】：盐城卫生职业技术学院;莫纳什大学工程学院化工系;墨尔本纳米制造中心;
【基金】：supported by the Australian Research Councile Discovery Projects(DP140100052,DP150103750) Advanced Study and Training Program of Jiangsu Vocational Education(2016TDFX013) High Level Talent Fund of Yancheng Vocational Institute of Health Sciences and Scientific Innovation Team Project of Yancheng Vocational Institute of Health Sciences~~
【分类号】：O643.36;TM911.4

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