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.     

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.     

气体扩散电极参数对阴离子交换膜燃料电池性能的影响

优化了碱性阴离子交换膜燃料电池（AAEMFC）使用的气体扩散电极（GDE）,发现催化层中PTFE含量与催化剂担载量对电池性能与其电化学动力学特征影响很大.采用i-V曲线,开路电压,电池内阻与在线的电化学阻抗谱与动力学分析,评估了所制GDE的电化学性能.在所研究的AAEMFC电极催化层中,PTFE的最佳含量是20%,Pt载量对膜电极三相界面、催化层导电性与催化剂利用率的影响极大.当制备的GDE催化层中Pt/C的Pt载量为1.0mg/cm²,PTFE含量为20%时,AAEMFC的峰电流密度在50^oC达到了213mW/cm².兼顾Pt催化剂的利用率与成本,在没有明显影响电池性能的情况下,Pt的担载量可降至0.5mg/cm².     

直接甲醇燃料电池催化活性层的优化

本文考察了直接甲醇燃料电池 (DMFC)不同催化剂载量的膜电极性能 .对催化剂层中Nafion含量进行优化 ,研究了Nafion含量对电池的阻抗的影响 .实验发现 :DMFC适宜的阳极Pt_Ru/C载量为Pt 4mg/cm2 、Nafion质量百分含量为 2 1.4 % ;高电流密度下 ,阴极Pt/C载量为Pt4mg/cm2 、Nafion质量百分含量为 2 1.4 %时 ,有较好的放电性能 ,继续增加Nafion含量 ,阴极的欧姆极化和浓差极化增大 ,电池性能下降     

气体电极反应动力学的薄膜旋转圆盘电极方法研究

薄膜旋转圆盘电极方法是一种常用的评价气体物质在纳米电催化剂上的反应活性的方法,但是在数据分析过程中经常忽视了气体反应物在催化剂层中到活性位点的传质可能对估算的反应动力学参数的影响.本文以氧电极反应为例,使用薄膜旋转圆盘电极研究了不同担载量Pt/C电极的氧还原活性.实验结果表明,根据Koutecky-Levich方程求算相同电位下的"表观动力学电流密度"(对Pt活性面积归一化的mA/cm2Pt)或比质量电流(mA/μg Pt)随Pt担载量的减小而增大,说明在估算动力学电流时不能忽略O2在催化剂层中的扩散传质,而气体在催化剂层中的传质与催化剂层的结构、厚度、纳米催化剂的分散度等密切相关.建议在使用薄膜旋转圆盘电极方法来研究纳米催化剂气体电极反应活性时,首先系统考察担载量、分散度与催化剂层厚的影响,然后根据不同担载量催化剂归一化后的动力学电流密度(或比质量电流)-电势曲线是否重合来验证得到的是否是真实的动力学电流,从而得到更为准确的评价结果.     

隔膜和熔融碳酸盐燃料电池 (MCFCS)性能的研究(英文)

用γ LiAO2 粉料和带铸法制备电池隔膜。隔膜有很高的阻窜能力和较低的欧姆极化。在电流密度为 2 0 0和 2 4 6mA/cm2 下放电时 ,用此膜组装的电池组 (三对电池 ,电极面积为 12 2cm2 )输出电压分别为 2 .0 1和 1.78V ,输出功率达 53.4W .于 2 0 0和 30 0mA/cm2 下放电时 ,单电池 (电极面积为 2 8cm2 )输出电压分别高于 0 .85和 0 .75V ,输出功率约 6 .6W .补偿隔膜收缩导致电池性能的提高 .     

碱性聚合物电解质燃料电池电极疏水性对性能的影响

本文报道H₂-O₂型碱性聚合物电解质燃料电池（APEFC）电极疏水性对放电性能的影响. 以季铵化聚砜（QAPS）或自交联型季铵化聚砜（xQAPS）碱性聚电解质（APE）作为隔膜和电极中的电解质（Ionomer）、聚四氟乙烯（PTFE）作为疏水添加剂调控催化层疏水性. 结果表明,阳极催化层疏水性的增强有利于提升电池放电性能,而阴极催化层疏水性适中时电池性能最优. 采用疏水性较强的xQAPS作为电解质并在阳极催化层中添加适量PTFE疏水剂,在60 ^oC和100%相对湿度的条件下,280 mA·cm^-2电流密度时,电池最高功率密度达132 mW·cm^-2.     

YSZ传导膜H_2S固体氧化物燃料电池

研究了Y2O3稳定的ZrO2(YSZ)氧离子传导膜H2S固体氧化物燃料电池性能。掺杂NiS、电解质、Ag粉和淀粉制备了双金属复合MoS2阳极催化剂,掺杂电解质、Ag粉和淀粉制备了复合NiO阴极催化剂,用扫描电镜对YSZ和膜电极组装(MEA)进行了表征,比较了不同电极催化剂的性能和极化过程,考察了不同温度对电池性能的影响。结果表明,双金属复合MoS2/NiS阳极催化剂在H2S环境下比Pt和单金属MoS2催化剂稳定,复合NiO阴极催化剂比Pt性能好,在电极催化剂中加入Ag可显著提高电极的导电性;与Pt电极相比,复合MoS2阳极和复合NiO阴极催化剂的过电位较小,阳极的极化比阴极侧小;温度升高,电池的电流密度与功率密度增加,电化学性能变好。在750℃、800℃、850℃和900℃及101.13 kPa时,结构为H2S、(复合MoS2阳极催化剂)/YSZ氧离子传导膜/(复合NiO阴极催化剂)、空气的燃料电池最大功率密度分别为30 mW/cm2、70 mW/cm2、155 mW/cm2及295 mW/cm2、最大电流密度分别为120 mA/cm2、240 mA/cm2、560 mA/cm2和890 mA/cm2。     

PEMFC电极中表面扩散现象的初步研究

制作双催化层结构的PEMFC电极.该双催化层由含有Nafion的内催化层、无Nafion的外催化层组成.循环伏安测试表明,未与Nafion直接接触的外催化层Pt/C催化剂也参与发生在"Pt/Nafion"界面氢原子的吸脱附反应和Pt表面含氧粒子的电化学氧化还原.当电势扫描速率较低时,未与Nafion直接接触的外层Pt/C催化剂,其对氢脱附电流的贡献和直接与Nafion接触的内催化层的Pt/C催化剂大致相当.以双催化层电极作PEMFC阴极,单电池(PEMFC)极化曲线测试表明,其阴极外催化层能明显地提高该单电池在活化极化区的输出性能.进一步证明了PEMFC阴极外催化层不与Nafion直接接触的Pt/C催化剂可通过其表面吸附含氧粒子的表面扩散参与发生在"Pt/Nafion"界面氧的电化学还原反应.上述实验为设计PEMFC电极提供了一定的新思路.     

质子交换膜燃料电池电极的一种新的制备方法

提出一种新的电极制备方法 ,在薄层催化层电极制备中加入造孔剂 ,并使用喷涂方法 ,使质子交换膜燃料电池 (PEMFC)电极中铂担量降到 0 .0 2mgPt/cm2 .与文献方法相比 ,新方法过程简单、成本低、易放大 .并通过实验得到电极的最佳组成为 :催化剂 :造孔剂 :Nafion =3:3:1 .采用此方法制备的电极 (0 .0 2mgPt/cm2 )与Nafion 1 1 5膜组装成电池 ,单池工作电压为 0 .7V时 ,每毫克铂可产生 2 0A的电流 ,每千瓦电池组仅需 72mgPt .     

High Pt utilization PEMFC electrode obtained by alternative ion-exchange/electrodeposition

High Pt utilization PEMFC electrodes were prepared by an alternative ion-exchange/electrodeposition (AIEE) technique. The results demonstrated that the MEA employing an AIEE electrode with a Pt loading of 0.014 mg Pt cm(-2) exhibits performance approximately 2.2 times larger than that employing a conventional Nafion-bonded Pt/C electrode with a same Pt loading.     

新型自增湿膜电极的制备及其燃料电池性能

质子交换膜燃料电池 (PEMFC)是以环境友好的方式输出高功率密度的电能 ,有望应用于动力电源、家用电源、通信电源及便携式电源等领域 [1] .在 PEMFC的应用开发中 ,成本正在逐渐降低 ,各种贮氢系统也相继出现 .然而要使 PEMFC实现产业化还必须简化复杂的运行系统 ,提高电池的功率体积比与功率质量比 .为此 ,自增湿 PEMFC被视为最有希望的燃料电池应用技术 .自增湿膜电极是实现自增湿技术的根本途径 .Watanabe等[2 ] 首先提出用 Pt微粒与 Si O2 或 Ti O2 掺杂在电解质膜中制备自增湿 MEA,Pt微粒有效地阻止了氢氧的交叉扩散 ,并在…     

墨水溶剂对低铂含量质子交换膜燃料电池性能的影响

Owing to the scarcity of platinum, it is of high importance to develop electrodes with low platinum metal loading and to thereby improve the utilization of Pt for the commercialization of proton-exchange membrane fuel cells (PEMFCs). In comparison to conventional high-platinum electrodes, the thickness of the catalyst layer (CL) is thinner and the interatomic Pt spacing is larger for the low-Pt loading electrodes. The distribution of electrolyte ionomer and the electrode morphology, which are strongly influenced by the solvents used in the fabrication process, are therefore increasingly important factors for achieving high performance in the membrane electrode assembly (MEA). In this work, different solvents with various dielectric constants and evaporation rates were used to prepare the inks for low-Pt loading cathode (0.1 mg·cm^-2) fabrication. First, the inks were fabricated by dispersing the catalyst and ionomer in different solvents which were then coated onto carbon paper to prepare the gas diffusion electrodes. The anode and cathode electrodes were then hot-pressed together with the Nafion membrane to produce the MEAs. The results showed a mixture of isopropanol-water (4:1) yielded the best-performing MEA during the single-cell tests compared to the other solvents tested. In order to elucidate the relationship between the performance of MEAs and the solvents, the structure and the surface morphology of the CL and the distribution of Nafion ionomer in the CL was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A comparison of the SEM and TEM images of representative samples indicated that the best performing electrode had a much improved homogeneity in the surface morphology as well as the dispersion of catalyst and ionomer. This was because of the moderate evaporation rate and better dispersion, caused by the increased hydrogen bonding and high dielectric constant, respectively. The results from dynamic light scattering (DLS) showed that the size of the catalyst and ionomer aggregates are influenced by the solvents. It is suggested that larger aggregates might help the formation of holes in the CL for gas diffusion and water removal, with the optimum size found to be around 400–800 nm. In conclusion, the MEA fabricated from the isopropanol-water solvent exhibited a significantly increased power density (1.79 W·cm^-2), and the utilization of Pt was increased to approximately 0.047 mg·W^-1, which is among the best-performing fuel cells reported to date.     

Influence of lanthanum on morphology and electrochemical performance of nano-platinum-based catalytic membrane electrode

The current research of platinum (Pt)–based catalysts focuses on reducing Pt loading in the catalysts while enhancing the catalytic activity. As a rare-earth element, lanthanum (La) has demonstrated good synergistic effect with Pt-based catalysts, because of its catalytic promoting capability and high dispersibility. Here, we fabricated La-doped nano-Pt-based catalytic membrane electrode using ion beam sputtering method. The effect of La on the morphology and electrochemical performance of the catalytic membrane electrode was investigated by scanning electron microscope, X-ray photoelectron spectroscopy, and electrochemical measurements. Compared with pure Pt-based sample, the electrochemical activity specific area of the La-doped sample increases by 74.59%, with 63.95% increase in exchange current density. The results also show that La₂O₃ enhances oxygen enrichment of the membrane electrode and reduces interfacial energy among Pt grains while pinning the grain boundaries. In addition, the inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurement shows that the Pt loading in the membrane electrodes is below 0.1 mg/cm². Thus, enhanced catalytic performance is achieved in catalysts with lower Pt loading.     

聚合物电解质膜燃料电池薄电极制备技术的研究

为降低聚合物电解质膜燃料电池 (PEMFC)电极中铂的载量 ,本文建立一种新的薄电极制备技术 (TEFT) ,制备了表面平滑、颗粒分布均匀的低铂载量电极 .结果表明当电极的铂载量为 1mg/cm2 ,用Nafion 117膜作电解质时 ,电池的最大功率密度达 0 30W·cm-2 .系统地考察了阴极中不同PTFE和Nafion含量对PEMFC性能的影响 .     

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.     

织构气体扩散层表面氢氧燃料电池阴极超低Pt载量催化层的磁控溅射法制备

采用磁控溅射技术在具有织构结构的气体扩散层(GDL)表面制备了可应用于氢氧质子交换膜燃料电池的超低Pt载量阴极催化层, 并通过SEM、 轮廓仪和XRD等测试方法表征了GDL及其载Pt后的形貌和物相, 利用XPS分析溅射Pt的化学价态, 使用电池测试台表征其电池性能. 测试结果表明, 磁控溅射法在GDL表面沉积的Pt催化层载量可控且分布均匀; 与商业GDL对比, Pt在织构GDL表面具有更大的可附着面积. 电池性能测试结果显示, 当Pt载量为0.04 mg/cm²时, 以织构GDL作基材的样品质量比功率高达26.25 kW/g Pt, 远大于商业GDL作基材时的17.76 kW/g Pt, 也大于同等Pt载量下商业Pt/C催化剂的24.00 kW/g Pt.     

Ti基纳米TiO_2-CNT-Pt复合电极制备、表征及电化学性能

以电合成前驱体Ti(OEt)4直接水解法和电化学扫描电沉积法制备Ti基纳米TiO2-CNT-Pt(Ti/nanoTiO2-CNT-Pt)复合电极.透射电镜(TEM)和X射线衍射(XRD)测试表明,锐钛矿型纳米TiO2粒子(粒径5～10nm)和碳纳米管(CNT)结合形成网状结构,Pt纳米粒子(平均粒径9nm)均匀地分散在纳米TiO2-CNT复合膜表面.循环伏安及计时电流测试表明,Ti/nanoTiO2-CNT-Pt复合电极具有高活性表面,对甲醇的电化学氧化具有高催化活性和稳定性,Pt载量为0.32mg/cm2时,常温常压下甲醇氧化峰电流达到480mA/cm2.     

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.