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.     

聚合物膜燃料电池的发展状况

介绍燃料电池的工作原理、催化剂有效应用、聚合物膜电解质及燃料储存和开发     

质子交换膜燃料电池中Pt/C及Pt合金/C催化剂的衰退机制研究综述

成本和耐久性依然是制约质子交换膜燃料电池商业化发展的两大瓶颈。首先综述了质子交换膜燃料电池阴极Pt/C催化剂在实际工作条件下的降解情况,并给出了可能的降解机制。结果表明,Pt/C催化剂在实际工作条件下,尤其是在汽车应用中是不稳定的,通常无法用作燃料电池阴极催化剂。而Pt合金催化剂因具有优异的氧还原催化性能和相对较好的耐久性,被认为有望解决成本和耐久性这两大难题,因此在质子交换膜燃料电池中日益得到重视和应用。但如何改善合金催化剂的耐久性依然是一个棘手的问题,文章最后详细综述了PtxCoy合金催化剂可能的衰退机理,以及可在一定程度上提高Pt合金催化剂耐久性的Pt单层结构和Pt核壳结构,这对催化剂的合成和设计具有一定的指导意义。     

Graphene-based bipolar plates for polymer electrolyte membrane fuel cells

Bipolar plates (BPs) are a major component of polymer electrolyte membrane fuel cells (PEMFCs). BPs play a multifunctional character within a PEMFC stack. It is one of the most costly and critical part of the fuel cell, and hence the development of efficient and cost-effective BPs is of much interest for the fabrication of next-generation PEMFCs in future. Owing to high electrical conductivity and chemical inertness, graphene is an ideal candidate to be utilized in BPs. This paper reviews recent advances in the area of graphene-based BPs for PEMFC applications. Various aspects including the momentous functions of BPs in the PEMFC, favorable features of graphene-based BPs, performance evaluation of various reported BPs with their advantages and disadvantages, challenges at commercial level products and future prospects of frontier research in this direction are extensively documented.     

利用生物质材料合成高性能氢氧燃料电池氧还原催化剂（英文）

制备廉价、高活性氧还原催化剂对于发展氢氧燃料电池清洁能源极为重要.在本论文中,我们利用黑木耳作为生物质材料,通过一种便捷的方法合成了高活性氧还原催化剂.黑木耳经水热和热解两个步骤,碳化形成BF-N-950催化剂.该催化剂在酸性和碱性溶液中的半波电势分别为0.77和0.91 V.采用BF-N-950催化剂作为膜电极得到的氢氧燃料单电池,峰值功率可达255 mW cm^-2.本文提出了使用生物质材料合成高性能氧还原催化剂的方法,为氢氧燃料电池的应用提供了有益探索.     

Dihydrogenimidazole modified silica-sulfonated poly(ether ether ketone) hybrid materials as electrolyte membranes for direct ethanol fuel cells

The present study reports on dihydrogenimidazole modified inorganic-organic mixed matrix membranes for possible application as a proton exchange membrane in direct ethanol fuel cells. The polymeric phase consisted mainly of sulfonated poly(ether ether ketone) (sPEEK) with a sulfonation degree of 55%. The inorganic phase was built up from hydrophilic fumed silica particles interconnected with partially hydrolyzed and condensed tetraethoxysilane with a total inorganic loading of 27.3%. This inorganic phase was further modified with N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (DHIM), which consists of an hydrolyzable inorganic part and a functional organic group. The influence of the modifier on the mixed matrix system was studied by means of various modifier concentrations in various aqueous-ethanolic systems (water, 2 M and 4 M ethanol). Modifier concentration and ethanol concentration of the ethanol-water mixture exhibited significant but opposite effects on the liquid uptake of the mixed matrix membranes. The proton conductivity as well as the proton diffusion coefficient as a function of modifier content showed a linear decrease. The proton conductivity as a function of temperature showed Arrhenius behavior and the activation energy of the mixed matrix membranes was 43.9 ± 2.6 kJ mol⁻¹. High selectivity of proton diffusion coefficient to ethanol permeability coefficient was obtained with high modifier concentrations. At low modifier concentrations, this selectivity was dominated by ethanol permeation and at high modifier concentrations by proton diffusion. The main electrolyte properties can be optimized by setting the DHIM content in mixed matrix membrane. With this approach, tailor-made membranes can be prepared for possible application in direct ethanol fuel cells.     

Antioxidant technology for durability enhancement in polymer electrolyte membranes for fuel cell applications

While polymer electrolyte membrane fuel cells (PEMFCs) have surged in popularity due to their low environmental impact and high efficiency, their susceptibility to degradation by in-situ generated peroxide and oxygen radical species has prevented their widespread adoption. To alleviate chemical attack on components of PEMFCs, particularly on polymer electrolyte membranes (PEMs), antioxidant approaches have been the subject of enormous interest as a key solution because they can directly scavenge and remove detrimental peroxide and oxygen radical species. However, a consequence is that long-term PEMFC device operation can cause undesirable adverse degradation of antioxidant additives provoked by the distinctive chemical/electrochemical environment of low pH, electric potential, water flux, and ion exchange/concentration gradient. Moreover, changes in the physical state such as migration, agglomeration, and dissolution of antioxidants by mechanical or chemical pressures are serious problems that gradually deteriorate antioxidant activity and capacity. This review presents current opportunities for and limitations to antioxidant therapy for durability enhancement in PEMs for electrochemical device applications. We also provide a summary of advanced synthetic design strategies and in-depth analyses of antioxidants regarding optimizing activity-stability factors. This review will bring new insight into the design to realization of ideal antioxidant nanostructures for PEMs and open up new opportunities for enhancing proliferation of durable PEMFCs.     

新型质子交换膜材料及其改性方法研究进展

综述了燃料电池用各种质子交换膜(PEM)材料及其改性方法．PEM材料包括全氟磺酸型离子交换树脂、聚苯并咪唑(PBI)、聚醚醚酮(PEEK)以及各种新型聚合物、嵌段共聚物等，而将这些材料制成PEM所采用的改性方法可分为磺化、酸基络合、杂化、共混、共聚、以及辐射接枝、等离子体等改性处理．还介绍了各种PEM材料的物性特点和PEM材料改性方法及其最新PEM研究报道．     

钨氧化合物的合成与性能研究进展

综述了近年来低维钨氧化物的研究动态,简要介绍了制备低维钨氧化物的方法和特点.评价以这些材料作为燃料电池阳极催化剂载体的铂基催化剂的催化活性及稳定性,并与目前普遍采用的商业碳质载铂(Pt/C)催化剂进行比较.最后,展望了此类载体材料的发展方向.     

质子交换膜燃料电池氮掺杂碳基催化剂研究进展

简要介绍了近年来氮掺杂碳基催化剂在质子交换膜燃料电池阴极氧还原方面的应用发展状况,详细总结了最近几年有关氮掺杂碳基催化剂制备及机理方面的研究结果,包括氮源前驱体种类、金属前驱体种类、金属的含量、碳源前驱体种类、热处理工艺等影响催化剂氧还原活性的主要因素,并指出了目前研究中的难点以及未来的发展方向。     

氧还原反应的量子化学模型及其催化活性指示符研究进展

氧还原反应是质子交换膜燃料电池的重要电化学过程.从分子(原子)水平研究氧还原反应对质子交换膜燃料电池催化剂开发具有重要的指导意义.因此,用于分子(原子)水平研究的量子化学方法被引入氧还原反应研究.简要综述了几种常用的氧还原反应量子化学模型及其催化活性指示符,并分析比较了这几种量子化学模型的适用范围.     

Functionalized graphene oxide and multi-walled carbon nanotubes in hexadecyl trimethyl ammonium bromide and chitosan matrix as metal-free catalyst for enhanced oxygen reduction reaction

The development of new catalysts for high-performance and cost-effective oxygen reduction is crucial in the commercialization of fuel cells. Herein, we demonstrate the use of a novel metal-free catalyst, hexadecyl trimethyl ammonium bromide (CTAB)-functionalized graphene oxide (GO) and multi-walled carbon nanotubes (MWCNT) in CTAB and chitosan matrix (CTAB/GO/MCWNT/CS), which exhibits a significant synergistic catalytic effect on oxygen reduction reaction. Compared with commercially available Pt/C catalysts, enhanced electrocatalytic activity, improved long-term operational stability, and excellent tolerance to methanol in alkaline fuel cells were observed for the novel composite catalyst.