直接乙醇燃料电池阳极催化剂载体的研究进展

主要介绍燃料电池的重要作用,指出直接乙醇燃料电池的优势以及目前面临的问题,论述直接醇类燃料电池阳极催化剂载体的研究现状,介绍具体的催化剂碳系载体、非碳系载体的优点以及不足之处,并且对直接乙醇燃料电池阳极催化剂载体的发展进行了展望。     

直接乙醇燃料电池阳极催化材料的研究进展

评述了直接乙醇燃料电池阳极催化剂研究过程中存在的主要问题，简述了DEFC阳极催化剂的电催化氧化反应机理，概述了目前研究的主要成就，并对今后直接乙醇燃料电池阳极催化材料发展方向进行了展望。     

直接甲醇燃料电池阳极催化剂的研究进展

直接甲醇燃料电池阳极催化剂是影响该类电池性能的关键技术之一，从铂基合金催化剂，铂-金属大环化合物催化刑，导电聚合物为载体的复合催化剂，以及非贵金属催化剂四方面综述了直接甲醇燃料电池阳极催化剂的研究进展。     

直接甲醇燃料电池非贵金属阳极催化剂研究进展

作为燃料电池的核心组成部分,催化剂的性能直接决定了燃料电池整体的性能。直接甲醇燃料电池(DMFCs)具有高能量转换效率、高能量密度、低环境污染等优点成为新能源研究领域的热点研究课题。阳极催化剂的性能直接影响着DMFCs的使用价值。非贵金属材料具备一定的电催化活性,较好的耐蚀性和较低的成本,有望成为继Pt/C催化剂后的下一代催化剂。石墨烯具备优异的导电性,巨大的比表面和良好的化学稳定性,成为催化剂的理想载体。本文介绍了近年来DMFCs非贵金属阳极催化剂的研究情况,归纳总结了目前燃料电池催化剂存在的相关问题,并初步拟定了石墨烯基非贵金属阳极催化剂的实验方案,最后对燃料电池的发展前景进行了展望。     

阴离子交换膜燃料电池阳极催化剂的研究进展

阴离子交换膜燃料电池(AEMFC)可使用非贵金属催化剂,且电极反应速率快。阳极催化剂的选择和制备对提高燃料氧化速率和燃料电池的电流密度及降低成本等有很大影响。本文从阴离子交换膜阳极催化剂的种类、制备方法,催化剂的载体等角度对阳极催化剂的研究现状进行分析。分析表明,在阳极催化剂中掺杂金属、金属氧化物或非金属氧化物,能充分发挥各元素的协同作用,从而提高催化剂的电催化性能;改进制备方法可以提高催化剂的比表面积,改变元素的分布。对催化剂载体进行改性以改善载体自身的孔径分布,提高比表面积和稳定性,或寻求导电性好、比表面积大、耐腐蚀的新载体材料(如SiC、Ti等),均可以提高催化剂的载量和催化剂在载体上的分散度等,从而提高阴离子交换膜燃料电池的性能。     

TiO_2纳米材料在直接甲醇燃料电池阳极催化剂中应用的研究进展

阳极催化剂是影响直接甲醇燃料电池(DMFC)性能及成本的主要因素,本文综述了TiO_2纳米粉体、TiO_2纳米管和TiO_2纳米纤维及其复合材料在DMFC阳极催化剂中应用的研究进展,并对其作用、对催化剂活性的影响机理等进行简要分析,展望了其应用前景。     

钯催化剂在燃料电池阳极中的研究进展

钯(Pd)作为燃料电池阳极催化剂,具有重要的市场应用前景。从纯Pd催化剂,负载型Pd催化剂,Pd基合金催化剂3个方面综述了近年来Pd催化剂在燃料电池阳极中的研究进展,介绍了其结构形态、载体、掺杂元素等对Pd催化剂的催化性能的影响。     

Co-Mo系耐硫阳极催化剂的制备与表征

采用溶胶一凝胶法制备了Co-Mo二元硫化物阳极催化剂.通过TG、SEM对催化荆进行表征,测定催化剂在1000℃以下时的电导率;通过比较催化剂在反应前后的红外光谱图,评价催化剂的耐硫性能.结果表明:Co-Mo阳极催化剂具较好的热稳定性,较大的孔隙率和电导率,以及优越的耐硫性能,满足固体氧化物燃料电池阳极催化剂的要求,是一种新型的耐硫阳极材料.     

直接乙醇燃料电池研究进展

介绍了直接乙醇燃料电池(DEFC)电催化氧化机理,分析了碳载铂催化剂等物质担载催化剂在DEFC中的性能,论述了电解质膜及DEFC性能的研究现状,指出了从阳极催化剂、电解质膜等方面提高DEFC性能的途径.     

直接硼氢化物燃料电池(DBFC)阳极催化剂的研究进展

直接硼氢化物燃料电池(DBFC)具有理论电池电压高和能量密度大等特点, 而其阳极催化剂是决定电池性能的关键因素之一。因此, 研究者们在提高阳极催化剂催化活性和降低催化剂成本方面开展了大量的研究工作。本文在简要介绍DBFC工作原理和阳极反应机理的基础上, 从催化剂种类和性能角度综述了近年来DBFC中贵金属、过渡金属以及储氢合金阳极催化剂的主要研究进展, 指出了阳极催化剂研究所面临的问题, 同时提出了今后的发展方向。     

Shape‐Dependent Activity of Ceria for Hydrogen Electro‐Oxidation in Reduced‐Temperature Solid Oxide Fuel Cells

Single crystalline ceria nanooctahedra, nanocubes, and nanorods are hydrothermally synthesized, colloidally impregnated into the porous La_0.9Sr_0.1Ga_0.8Mg_0.2O_3‐δ (LSGM) scaffolds, and electrochemically evaluated as the anode catalysts for reduced temperature solid oxide fuel cells (SOFCs). Well‐defined surface terminations are confirmed by the high‐resolution transmission electron microscopy — (111) for nanooctahedra, (100) for nanocubes, and both (110) and (100) for nanorods. Temperature‐programmed reduction in H₂ shows the highest reducibility for nanorods, followed sequentially by nanocubes and nanooctahedra. Measurements of the anode polarization resistances and the fuel cell power densities reveal different orders of activity of ceria nanocrystals at high and low temperatures for hydrogen electro‐oxidation, i.e., nanorods > nanocubes > nanooctahedra at T ≤ 450 °C and nanooctahedra > nanorods > nanocubes at T ≥ 500 °C. Such shape‐dependent activities of these ceria nanocrystals have been correlated to their difference in the local structure distortions and thus in the reducibility. These findings will open up a new strategy for design of advanced catalysts for reduced‐temperature SOFCs by elaborately engineering the shape of nanocrystals and thus selectively exposing the crystal facets.     

Selective catalysts for the hydrogen oxidation and oxygen reduction reactions by patterning of platinum with calix[4]arene molecules

The design of new catalysts for polymer electrolyte membrane fuel cells must be guided by two equally important fundamental principles: optimization of their catalytic behaviour as well as the long-term stability of the metal catalysts and supports in hostile electrochemical environments. The methods used to improve catalytic activity are diverse, ranging from the alloying and de-alloying of platinum to the synthesis of platinum core-shell catalysts. However, methods to improve the stability of the carbon supports and catalyst nanoparticles are limited, especially during shutdown (when hydrogen is purged from the anode by air) and startup (when air is purged from the anode by hydrogen) conditions when the cathode potential can be pushed up to 1.5 V (ref. 11). Under the latter conditions, stability of the cathode materials is strongly affected (carbon oxidation reaction) by the undesired oxygen reduction reaction (ORR) on the anode side. This emphasizes the importance of designing selective anode catalysts that can efficiently suppress the ORR while fully preserving the Pt-like activity for the hydrogen oxidation reaction. Here, we demonstrate that chemically modified platinum with a self-assembled monolayer of calix[4]arene molecules meets this challenging requirement.     

High-Performance Ammonia Protonic Ceramic Fuel Cells Using a Pd Inter-Catalyst

This study reports the performance and durability of a protonic ceramic fuel cells (PCFCs) in an ammonia fuel injection environment. The low ammonia decomposition rate in PCFCs with lower operating temperatures is improved relative to that of solid oxide fuel cells by treatment with a catalyst. By treating the anode of the PCFCs with a palladium (Pd) catalyst at 500 °C under ammonia fuel injection, the performance (peak power density of 340 mW cm⁻² at 500 °C) is approximately two-fold higher than that of the bare sample not treated with Pd. Pd catalysts are deposited through an atomic layer deposition post-treatment process on the anode surface, in which nickel oxide (NiO) and BaZr_0.2Ce_0.6Y_0.1Yb_0.1O_3–δ (BZCYYb) are mixed, and Pd can penetrate the anode surface and porous interior. Impedance analysis confirmed that Pd increased the current collection and significantly reduced the polarization resistance, particularly in the low-temperature region (≈500 °C), thereby improving the performance. Furthermore, stability tests showed that superior durability is achieved compared with that of the bare sample. Based on these results, the method presented herein is expected to represent a promising solution for securing high-performance and stable PCFCs based on ammonia injection.     

A redox-stable efficient anode for solid-oxide fuel cells

Solid-oxide fuel cells (SOFCs) promise high efficiencies in a range of fuels. Unlike lower temperature variants, carbon monoxide is a fuel rather than a poison, and so hydrocarbon fuels can be used directly, through internal reforming or even direct oxidation. This provides a key entry strategy for fuel-cell technology into the current energy economy. Present development is mainly based on the yttria-stabilized zirconia (YSZ) electrolyte. The most commonly used anode materials are Ni/YSZ cermets, which display excellent catalytic properties for fuel oxidation and good current collection, but do exhibit disadvantages, such as low tolerance to sulphur and carbon deposition when using hydrocarbon fuels, and poor redox cycling causing volume instability. Here, we report a nickel-free SOFC anode, La0.75Sr0.25Cr0.5Mn0.5O3, with comparable electrochemical performance to Ni/YSZ cermets. The electrode polarization resistance approaches 0.2 Omega cm2 at 900 degrees C in 97% H2/3% H2O. Very good performance is achieved for methane oxidation without using excess steam. The anode is stable in both fuel and air conditions, and shows stable electrode performance in methane. Thus both redox stability and operation in low steam hydrocarbons have been demonstrated, overcoming two of the major limitations of the current generation of nickel zirconia cermet SOFC anodes.     

二维碳化钛/碳纳米管负载铂钌粒子的制备及电催化性能研究

直接甲醇燃料电池因操作方便、转化效率高、操作温度低、污染少以及液体燃料易存储易运输等优势具有良好的应用前景, 但现有阳极催化剂存在催化活性低、抗CO中毒性差等缺点, 制约了其商业化应用前景。本研究采用三步法制备得到了一系列不同Pt、Ru配比的PtRu/(Ti₃C₂T_x)_0.5-(MWCNTs)_0.5阳极催化剂材料, HF腐蚀Ti₃AlC₂得到Ti₃C₂T_x, 与酸化处理的多壁碳纳米管(MWCNTs)复合后通过溶剂热法负载Pt、Ru颗粒。通过XRD、SEM、EDS、TEM、XPS等分析铂钌的协同关系。结果表明: Ru原子与Pt原子晶格混合, 形成了粒径约3.6 nm的铂钌双金属合金。电化学分析结果表明: Pt₁Ru_0.5/(Ti₃C₂T_x)_0.5-(MWCNTs)_0.5催化剂具有最佳的电化学性能, 其电化学活性面积(Electrochemical Active Area, ECSA)为139.5 m ²/g, 正向峰电流密度为36.4 mA/cm ²。     

直接甲醇燃料电池阳极电催化剂材料的研究

评述了直接甲醇燃料电池阳极电催化剂研究中的几个热点问题 ,简述了催化剂材料的制备方法和最新的发展情况 ,概述了铂基二元、三元、四元催化剂材料的研究现状、取得的主要成果和存在的主要问题 ;铂基钙钛矿类和非铂基催化剂的成本低 ,但需要进一步解决在酸性介质中的寿命短和活性低的问题。     

Formation, microstructural characteristics and stability of carbon supported platinum catalysts for low temperature fuel cells

Supported platinum electrocatalysts are generally used in low temperature fuel cells to enhance the rates of the hydrogen oxidation and oxygen reduction reactions. In such catalysts, the high surface to volume ratios of the platinum particles maximize the area of the surfaces available for reaction. It is the structure and proper dispersal of these platinum particles that make low-loading catalysts feasible for fuel cell operation, lowering the cost of the system. If the platinum particles cannot maintain their structure over the lifetime of the fuel cell, change in the morphology of the catalyst layer from the initial state will result in a loss of electrochemical activity. This loss of activity in the platinum/carbon catalysts due to the agglomeration of platinum particles is considered to be a major cause of the decrease in cell performance, especially in the case of the cathode. In the light of the latest advances on this field, this paper reviews the preparation methods of these catalysts, their microstructural characteristic and their effect on both thermal and in cell conditions stability.     

Multifunctional Ir–Ru alloy catalysts for reversal-tolerant anodes of polymer electrolyte membrane fuel cells

To address the problem of fuel starvation in fuel-cell electric vehicles,which causes cell voltage reversal and results in cell failure when repeated continuously,we developed a reversal-tolerant anode(RTA) to promote water oxidation in preference to carbon corrosion.Graphitized carbon-supported Ir-Ru alloys with different compositions are employed as RTA catalysts in an acidic polyol solution and are shown to exhibit composition-dependent average crystallite sizes of <5.33 nm.The adopted approach allows the generation of relatively well-dispersed Ir-Ru alloy nanoparticles on the carbon support without severe agglomeration.The activity of IrRu₂/C for the hydrogen oxidation reaction is 1.10 times that of the stateof-the-art Pt/C catalyst.Cell reversal testing by simulation of fuel starvation reveals that the durability of IrRu₂/C(~7 h) significantly exceeds that of the conventional Pt/C catalyst(~10 min) and is the highest value reported so far.Thus,the developed Ir-Ru alloy catalyst can be used to fabricate practical RTAs and replace Pt catalysts in the anodes of polymer electrolyte membrane fuel cells.