聚苯胺修饰Pt/C催化剂对质子交换膜燃料电池动态响应的促进作用

将超级电容器材料聚苯胺引入电极催化剂中以缓冲燃料电池负载的变化.以硫酸为掺杂剂,将化学法合成的聚苯胺(PANI)与Pt/C超声分散混合,制成PANI-Pt/C催化剂.PANI-Pt/C的循环伏安测试和作为质子交换膜燃料电池阴极电催化剂的电池性能测试表明,PANI含量为10%时能够提高Pt/C催化剂对氧的还原动力学速度和燃料电池放电性能.电池在不同电流负载下的电压动态响应和对电池脉冲电流的动态响应以及PANI-Pt/C催化剂多电位电势阶跃计时电流测试显示,聚苯胺在催化剂中具有在瞬间电流负载时缓冲电池电压和电池大电流放电时平稳电压的作用.     

燃料电池碳基氧还原催化剂的设计与应用

燃料电池以高比能、低污染等独特优势,备受研究者的广泛关注。然而,燃料电池的商业化应用受到电极催化剂的性能、隔膜性能与成本等方面的限制。其中,氧还原反应作为燃料电池阴极的关键电极反应,其催化剂的电催化活性显著影响燃料电池性能和生产成本。因此,氧还原催化剂一直是燃料电池研究重要方向之一。碳基催化剂表现出了类似贵金属的电催化活性,通过优化碳基催化剂的结构及表面电子性质,能够降低氧还原反应过电势,促进氧还原四电子的反应过程,从而实现更高的能量转化效率。针对碳基催化剂在燃料电池中的基础应用,本文综述了近年来杂原子掺杂以及非贵金属与杂原子协同掺杂碳基催化剂的设计思路、电催化性能和潜在的催化机理等最新研究进展,并对未来发展方向进行了总结与展望。     

静电纺丝制备质子交换膜燃料电池催化剂层综述

质子交换膜燃料电池催化剂层在成本、耐久性以及性能上的局限是制约燃料电池汽车商业化的瓶颈. 已有文献证明静电纺丝技术制备的纳米纤维催化剂层能提高催化剂利用率、增加三相界面和三相通道以及提高耐久性. 作者结合所在课题组的工作综述了静电纺丝技术制备质子交换膜燃料电池催化剂层的研究进展. 首先,介绍了质子交换膜燃料电池催化剂层的发展历程,并从制备方式和结构两个方面对其进行分类和总结;接下来,从静电纺丝纳米纤维催化剂层的制备、物理特性表征、电化学性能分析及耐久性表征等方面进行了总结;最后,从三相界面、三相通道以及量产适用性的视点比较了三种结构的催化剂层,介绍了质子交换膜燃料电池催化剂层的发展趋势,并梳理了静电纺丝法制备质子交换膜燃料电池催化剂层领域待研的问题.     

低温燃料电池贵金属催化剂的老化

催化剂的老化是导致燃料电池性能衰减的重要因素之一.对于低温燃料电池,贵金属催化剂的老化主要体现在粒径的增长、金属氧化态的改变、组分的迁移和流失以及碳载体的腐蚀四个方面.本文综述了低温燃料电池贵金属催化剂老化方面的最新研究进展,探讨了导致催化剂老化的主要原因.     

直接硼氢化物燃料电池

直接硼氢化物燃料电池是一种新型的燃料电池,具有理论比能量高,产物清洁无污染,燃料易于储存和运输等特点,可广泛应用于小型便携式电子产品和移动电源,近年来受到越来越多研究者的关注。本文在介绍了直接硼氢化物燃料电池工作原理的基础上讨论了阳极催化剂、阴极催化剂的研究进展,并探讨了电解液和温度等条件对电池性能的影响,简要分析了发展直接硼氢化物燃料电池面临的主要问题。     

双极界面聚合物膜燃料电池Ⅰ:膜电极构型

双极燃料电池是一类新型的具有酸碱双极反应界面的聚合物膜燃料电池,其潜在的优势在于:(1)在碱性催化层中可利用非贵金属催化剂,降低电池成本;(2)双极反应界面上的水生成/解离反应可调节电池的水传输特性,形成电池的自增湿机制.尽管双极燃料电池理论上具有如此显著的优势,但其研究还处于起步阶段,尚缺乏大量有力的理论和实验依据.通过构建四种不同界面结构的双极膜电极,系统地研究了双极界面对电池性能的影响.结果表明,仅含有水生成界面的双极燃料电池构型最有利于电池输出性能的提升,并且成功利用这一构型验证了双极燃料电池自增湿稳定放电的特性.双极燃料电池的发展将有力的推动便携式自增湿燃料电池的进步.     

质子交换膜燃料电池MnO2-Pt/C复合催化剂阴极的富氧作用

质子交换膜燃料电池空气电极阴极催化剂的富氧作用是提高其性能的关键.应用化学氧化法制备MnO2-Pt/C复合催化剂,研究MnO2的富氧作用,应用CV、CP、TEM等方法表征该催化剂,并组装成单电池测试其性能.     

铂合金氧还原催化剂:合成、结构和性能（英文）

质子交换膜燃料电池是一种将燃料中的化学能直接转化为电能的装置,它具有转化效率高、能量密度高、低温启动、易于操作等优点,因而被认为是最具发展前景的新能源利用方式,在电动汽车、便携电源及分散式电站有着广泛应用.但是,目前质子交换膜燃料电池技术的发展面临着巨大挑战,主要问题包括高成本、低功率密度和低寿命.众所周知,质子交换膜燃料电池中的阴极氧还原反应在酸性条件下是一个复杂的四电子过程,动力学速度缓慢,限制了电池的最终性能.目前大量使用的阴极氧还原催化剂是细小的铂或铂合金纳米颗粒负载在碳载体上,其成本占燃料电池总成本的比例最大.制约燃料电池商业化发展的另一个重要问题是电池寿命低,其中氧还原催化剂的稳定性是决定电池寿命的主要因素.在这样的研究背景下,如何降低催化剂中铂的用量、提高催化剂活性和稳定性显得尤为重要,这也是近年来国内外学者研究的热点.在铂基合金催化剂中,通常采用过渡金属元素作为掺杂元素,由于原子半径不匹配(几何效应)以及电子结构不同(电子效应),合金催化剂表现出优于纯铂催化剂的催化性能.近几年,对于铂基合金催化剂的研究已取得重大进展,以合金组成和结构研究为基础,通过精确控制原子结构、调...     

金属铝燃料电池的研究

铝是一种丰富廉价的有色金属，金属铝电池作为一种新型燃料电池，具有低成本、无毒害、高功率、高能量密度等优点。本文简述了金属铝电池的工作原理，并对铝阳极、空气阴极、催化剂、电解液和铝燃料电池的应用等方面的研究概况进行了叙述。     

Fe-N-C 类催化剂在碱性燃料电池中的研究进展

随着阴离子交换膜的出现、发展和应用,碱性燃料电池的优势日趋明显,针对碱性燃料电池的研究也更广泛而深刻. 在碱性燃料电池中,除了其固有的对催化剂的高包容性和动力学优越性,阴离子交换膜让阴离子定向迁移,从而实现了很好的水相管理,降低了电池中“水涝”的几率,也提供了更广阔的燃料选择空间. 氧还原反应是碱性燃料电池中的重要部分,且其反应动力学相较于氢氧化反应缓慢. 因此,选择并研制合适的阴极氧还原反应催化剂,是提高碱性燃料电池性能和促进燃料电池规模化使用的关键. Fe-N-C类催化剂因其在碱性条件下接近甚至优于 Pt 基催化剂的性能,被视为最有潜力替代 Pt 的非贵金属催化剂. 本文从近 5 年来 Fe-N-C 类催化剂的合成方法、催化活性位点和氧还原反应机理以及在燃料电池中的应用三方面进行了综述.      

Single-wall carbon nanotube-based proton exchange membrane assembly for hydrogen fuel cells

A membrane electrode assembly (MEA) for hydrogen fuel cells has been fabricated using single-walled carbon nanotubes (SWCNTs) support and platinum catalyst. Films of SWCNTs and commercial platinum (Pt) black were sequentially cast on a carbon fiber electrode (CFE) using a simple electrophoretic deposition procedure. Scanning electron microscopy and Raman spectroscopy showed that the nanotubes and the platinum retained their nanostructure morphology on the carbon fiber surface. Electrochemical impedance spectroscopy (EIS) revealed that the carbon nanotube-based electrodes exhibited an order of magnitude lower charge-transfer reaction resistance (R(ct)) for the hydrogen evolution reaction (HER) than did the commercial carbon black (CB)-based electrodes. The proton exchange membrane (PEM) assembly fabricated using the CFE/SWCNT/Pt electrodes was evaluated using a fuel cell testing unit operating with H(2) and O(2) as input fuels at 25 and 60 degrees C. The maximum power density obtained using CFE/SWCNT/Pt electrodes as both the anode and the cathode was approximately 20% better than that using the CFE/CB/Pt electrodes.     

Triarylphosphine-stabilized platinum nanoparticles in three-dimensional nanostructured films as active electrocatalysts

Ligand-stabilized platinum nanoparticles (Pt NPs) can be used to build well-defined three-dimensional (3-D) nanostructured electrodes for better control of the catalyst architecture in proton exchange membrane fuel cells (PEMFCs). Platinum NPs of 1.7 +/- 0.5 nm diameter stabilized by the water-soluble phosphine ligand, tris(4-phosphonatophenyl)phosphine (TPPTP, P(4-C6H4PO3H2)3), were prepared by ethylene glycol reduction of chloroplatinic acid and subsequent treatment of the isolated nanoparticles with TPPTP. The isolated TPPTP-stabilized Pt NPs were characterized by multinuclear magnetic resonance spectroscopy (31P and 195Pt NMR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS). The negatively charged TPPTP-Pt NPs were electrostatically deposited onto a glassy carbon electrode (GCE) modified with protonated 4-aminophenyl functional groups (APh). Multilayers were assembled via electrostatic layer-by-layer deposition with cationic poly(allylamine HCl) (PAH). These multilayer films are active for the key hydrogen fuel cell reactions, hydrogen oxidation (anode) and oxygen reduction (cathode). Using a rotating disk electrode configuration, fully mass-transport limited kinetics for hydrogen oxidation was obtained after 3 layers of TPPTP-Pt NPs with a total Pt loading of 4.2 microg/cm2. Complete reduction of oxygen by four electrons was achieved with 4 layers of TPPTP-Pt NPs and a total Pt loading of 5.6 microg/cm2. A maximum current density for oxygen reduction was reached with these films after 5 layers resulting in a mass-specific activity, i(m), of 0.11 A/mg(Pt) at 0.9 V. These films feature a high electrocatalytic activity and can be used to create systematic changes in the catalyst chemistry and architecture to provide insight for building better electrocatalysts.     

Using layer-by-layer assembly of polyaniline fibers in the fast preparation of high performance fuel cell nanostructured membrane electrodes

Membrane electrode assemblies (MEA) for fuel cells require optimization of their nanoscale organization to reach performance parameters, which include enhanced power density, increased catalyst utilization and reduced cost. We applied sprayed layer-by-layer assembly to produce a high activity MEA for H(2)/O(2) fuel cells from polyaniline fibers (PANI-F). This technique produces "fast-prepared" membranes with nanoscale structure, which allows to adequately address specific tuning of their porosity, platinum loading, electronic conductivity, and proton conductivity. Pt nanoparticles were attached to the PANI-F in a reaction of selective heterogeneous nucleation. After functionalization, Pt/PANI-F were assembled with Nafion. Microscopic investigation revealed that functionalized polyaniline fibers formed a highly porous yet tight network of interpenetrating conductors connected to the catalytic Pt particles. The Pt/PANI-F LBL ultrathin MEA demonstrated a power densitiy of 63 mW cm(-2) and yielded a Pt utilization of 437.5 W g(-1) Pt which is comparable to the traditional fuel cell using carbon black as Pt support. Moreover, the amount of Pt used in this work is almost 2 times lower than for usual carbon-supported Pt catalysts.     

The Mass Transfer of Proton on Meniscus Nafion/Pt/HOPG Electrode

Proton-exchange membrane fuel cells (PEMFCs) recently have been studied extensively because of their high performance^[1-3]. Since a small contacting area between the platinum catalyst and polymer electrolyte in PEMFCs, the platinum utilization is very important for this kind of cells. In order to improve the platinum utilization, Nafion solution is often impregnated into the gas-diffusion electrodes of PEMFCs. We introduced a partially immersed Nafion-coated electrode, Nafion/Pt/HOPG(highly oriented pyrolytic graphite) as a model electrode in PEMFC, to examine the effects of Nafion coating on the mass transport of hydrogen and proton at the meniscus and supermeniscus formed on the electrodes.     

In situ grown nanoscale platinum on carbon powder as catalyst layer in proton exchange membrane fuel cells (PEMFCs)

An extensive study has been conducted on the proton exchange membrane fuel cells (PEMFCs) with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode (GCE) to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic (IV) acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm (diameter)×10 nm (length) by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry (CV) and scanning electron microscope (SEM) as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants (oxygen or hydrogen).     

Pt纳米粒子修饰的多孔硅电极的制备及其电催化性能

通过循环伏安法电沉积使直径约为7 nm的Pt纳米粒子均匀地分散于多孔硅表面, 拟用作微型质子交换膜燃料电池的催化电极. 与刷涂法相比较, 电沉积Pt纳米粒子的多孔硅电极(Pt/Si)呈现出高的Pt利用率和增强的电催化活性. 当Pt载量为0.38 mg•cm−2时, 其电化学活性比表面积高达148 cm2•mg−1, 是刷涂相近质量的纳米Pt/C催化剂的多孔硅电极Pt-C/Si的2倍多；该修饰电极对甲醇氧化也呈现了增强的催化性能和好的稳定性, 在0.5 V(vs SCE)极化1 h后电流密度为4.52 mA•cm−2, 而刷涂了相近Pt量的Pt-C/Si电极的电流密度只有0.36 mA•cm−2.     

层级多孔碳载铂催化剂的制备及可达性

层级多孔碳作为氧还原铂基催化剂载体的选择之一, 简单的旋转圆盘电极(RDE)验证此类催化剂具有较高的氧还原活性, 但几乎都缺少膜电极(MEA)性能验证, 实用性无法保证. 本文设计制备了基于聚苯胺的层级多孔碳（NHPC）载铂催化剂（Pt/NHPC850）, 研究了其氧还原活性、 MEA质子传输和氧传输特性. RDE测试研究表明, Pt/NHPC850催化剂在低I/C（离聚物与碳载体质量比）时的面积活性低于实心碳载铂催化剂（Pt/XC-72）, 但当I/C增大到与膜电极中一致时, 由于Nafion树脂对Pt催化剂的毒化作用增强, 其面积活性反而优于 Pt/XC-72. Pt/NHPC850催化剂的高Pt分散性及其优异的抗Nafion毒化性能, 使其在I/C为0.8时的质量活性为Pt/XC-72催化剂的1.34倍. MEA质子传输研究表明, 即使在高加湿条件下, Pt/NHPC850质子电阻率仍高达72.6 mΩ·cm², 为Pt/XC-72的3倍. Pt/NHPC850制备的膜电极极化曲线在500 mA/cm²电流密度下性能迅速下降, Pt/NHPC850的氧增益电压达到144.4 mV, 比Pt/XC-72高56.7 mV. 表明Pt/NHPC850膜电极的质子传输和氧传输性能较差. 对比Pt/NHPC850催化剂的RDE和MEA的测试结果, 说明以层级多孔碳为载体的铂碳催化剂虽然耐Nafion毒化能力提高, 但是质子和氧气的氧传输性较差, 此类层级多孔碳还需进一步优化其结构, 才有可能满足低铂质子交换膜燃料电池（PEMFC）的应用需求.     

正交设计法优化PEMFC催化层的最佳配比

利用正交实验设计法优选PEMFC电极催化层制备的最佳条件.实验证实亲水电极(催化层中不含PTFE)性能优于疏水电极.在该工艺条件下,当Nafion的含量为1.4mg·cm-2,Pt含量为0.4mg·cm-2时,以常压的H2和空气分别作为燃料气和氧化剂,电池的最高功率可达到0.37W·cm-2.研究表明,提高Pt/C中的Pt含量将是提高催化剂性能的有效途径.     

Nanostructure Pt Electrode Obtained via Self-assembly of Nanoparticles on Conductive Oxide-coated Glass Substrate

Self-assembly of platinum nanoparticles were applied to fabrication of counter electrode for dye-sensitized solar cells on conductive oxide-coated glass substrate. The present Pt electrode exhibits high exchange current density of 220 mA/cm^2, which is comparable to those prepared by electrodeposition, magnetron sputtering or thermal decomposition of platinum chloride. After analysis by transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), it was found that the catalyst was structurally characterized as nanosized platinum metal clusters and was continuously arranged on electrode surface. The present nanostructure electrode had high electrocatalytic activity for the reduction of iodine in organic solution.     

纳米颗粒结合ZIF-67衍生的PtCo-NC催化剂用于醇类燃料电氧化

Alcohols fuel electro-oxidation is significant to the development of direct alcohols fuel cells, that are considered as a promising power source for portable electronic devices. Currently, the catalyst was restricted by the serious poisoning effect and high cost of noble metals. Developing low-cost Pt alloy with high performance and anti-CO poisoning ability was highly desired. In this work, PtCo-NC catalyst was synthesized by combining Pt nanoparticles with ZIF-67 after annealing in the tube furnace and the in situ generated N-doped carbon from ZIF-67 was functionalized to support the PtCo alloy nanoparticle. The structure and morphology were probed by X-ray diffraction, scanning electron microscope and transmission electron microscope, and the electrochemical performance was evaluated for alcohols of methanol and ethanol oxidation in the acid electrolyte. Compared with the reference sample of Pt/C, several times performance enhancement for alcohols fuel oxidation was found on PtCo-NC catalyst as well as the good catalytic stability. Specifically, the peak current density of PtCo-NC was 79.61 mA∙cm⁻² for methanol oxidation, about 2.2 times higher than that of the Pt/C electrode (36.97 mA∙cm⁻²) and 2.5 times higher than that of the commercial Pt/C electrode (31.23 mA∙cm⁻²); it was 62.69 mA∙cm^–2 for ethanol oxidation, about 1.65 times higher than that of Pt/C catalyst (37.99 mA∙cm⁻²) and commercial Pt/C electrode (37.77 mA∙cm⁻²). These catalytic performances were also much higher than some analogous catalysts developed for alcohols fuel oxidation. A much higher anti-CO poisoning ability was demonstrated by the CO stripping voltammetry experiment, in which the CO_ad oxidation peak potential for PtCo-NC was 0.46 V, ca. 110 mV negative shift compared with Pt/C catalyst at 0.57 V. A strong electronic effect was indicated by the peak position shifting to the lower binding energy direction by 0.3 eV on PtCo-NC compared with Pt/C reference catalyst. According to the d-band center theory, the electron-enriched state of Pt will decrease the interaction strength of poisoning intermediates adsorbed on its surface; Moreover, according to the bifunctional catalytic mechanism, the presence of Co can form the adsorbed oxygen-containing species (―OH) more easily than Pt at low potentials, and this oxygen-species were helpful in the oxidation of CO_ad at neighboring Pt sites. The high catalytic performance for alcohols fuel oxidation could be due to the largely improved anti-CO poisoning ability and the synergistic effect between the in situ formed PtCo nanoparticles and the N-doped carbon support.