组合式再生燃料电池双效氧电极催化剂制备与表征

介绍了组合式再生燃料电池基本特点,简要回顾了组合式再生燃料电池中双效氧电极催化剂研究现状。利用还原沉积法制备了PtIr／C双效氧电极催化剂,对催化剂进行了XRD表征。以三电极体系对催化剂进行了析氧和溶氧双反应的催化活性评价,结果表明：Pt主要催化燃料电池模式下的溶氧反应,而Ir主要催化水电解模式下的析氧反应。     

喹啉电化学加氢催化剂的制备及性能研究

为了开发对喹啉具有催化作用的材料，通过购买催化剂Pt/C、Ru/C和Pd/C分别与玻碳电极(GCE)制备成工作电极并进行LSV测试，对产生还原峰的电位进行6 h的电解，最后对阴极电解液进行GC-MS测试。通过测试表明，以Pt/C和Ru/C材料为电极，电解后的阴极电解液生成了2-甲基萘，2-甲基萘具有高于喹啉的储氢密度和燃烧热，可用作燃料电池燃料和燃烧用的燃料，实现氢能的储存。     

乙烷质子交换膜燃料电池的研究

研究了以乙烷作为燃料、全氟磺酸高分子膜(Nafion膜)作为质子交换膜、Pt或Pt-Ru作为电极催化剂主要组分、并通过掺杂Nafion膜作为电极内的离子导体构成的燃料电池电化学性能.研究了两种电极催化剂:Pt与Pt-Ru复合催化剂的制备及构成的单电池在不同温度及运行时间下的电化学性能.温度增加,电池性能变好;运行时间增加,电池性能下降,在相同的温度与运行时间下,Pt-Ru复合催化剂构成的电池比Pt催化剂构成的电池极化小.通过分析电极反应产物,探讨了乙烷电极及电池的反应机理.结构为C2H6,( Pt-Ru+膜材料复合阳极)/Nafion膜/(Pt+膜材料复合阴极),O2 的质子交换膜燃料电池,在150℃时,电池的最大输出电流和功率密度分别高达70 mA·cm-2和22 mW·cm-2.     

燃烧法制备Ru_xIr_(1-x)O_2析氧催化剂

固体聚合物电解质水电解技术SPE具有能量效率高、产品纯度高等优点。因此在制氢、航天、军事等领域中具有重要应用前景。通过采用H_2IrCl_6与RuCl_3作为原料,采用糊精作为胶体成型剂,并分别在450℃、500℃和550℃对粉体进行烧结,制备了纳米级的析氧电极催化剂。考察了Ir与Ru之间的摩尔比对于催化剂性能影响。随着增加Ir的含量,电极的析氧活性升高,Ir的摩尔含量为67%,电极性能最好。考察不同烧结温度对Ru_xIr_(1-x)O_2氧电极催化剂影响,发现最佳烧结温度为500℃。通过该方法制备的催化剂在电解水膜电极中使用,在25℃常压下,电流为1 Acm~(-2)时的电解水电压为2.3 V。     

常温下以甲烷为燃料的质子交换膜燃料电池发电可行性研究

尝试了常温下以甲烷为燃料的质子交换膜燃料电池发电的可能性，研究了温度和阳极催化剂对其燃料电池开路电压和放电性能的影响。结果表明，甲烷在常温下能够进行电化学氧化，随着电池工作温度的升高，燃料电池的开路电压和功率密度逐渐增加。阳极催化剂的铂含量和催化剂的组成对甲烷的电化学氧化具有非常大的影响。90℃下使用Pt（40wt．％）-Ru（20wt．％）／C为阳极催化剂（催化剂担载量：（2mg Pt＋1 mg Ru）·cm^-2），在以甲烷为燃料时，质子交换膜燃料电池功率密度达到了5．4mW·cm^-2。     

国外炭黑文摘

碳载体臭氧处理对直接甲醇燃料电池用Pt—Ru／C催化剂性能的影响；PVdF粘结剂对LiCoO2电极稳定性的影响；ZnFe2O4基气敏元件中添加NiO／TiO2对形成厚胶膜的影响；电压对HDPE／炭黑复合料NTC区导电性的影响；各种催化剂对LiAIH4脱氢性和加氢性的影响……     

鸡蛋黄热解制备高效双功能电催化剂

廉价高效的可催化氧还原反应（ORR）和析氧反应的双功能电催化剂是实现可再生燃料电池和金属-空气电池等化学电源大规模商业化应用的关键因素。以鸡蛋黄和六水合氯化钴为前驱体,采用简单的一步热解法制备了杂原子掺杂碳材料（HDC）负载Co₂P纳米颗粒双功能电催化剂（Co₂P-HDC）。采用SEM、TEM、XRD以及XPS等表征手段对所得催化剂的微观形貌、晶体结构以及表面元素组成进行了分析表征。运用旋转圆盘电极（RDE）技术考察了Co₂P-HDC在碱性介质中催化ORR和OER的性能。结果表明,Co₂P-HDC催化剂表现出与商品Pt/C催化剂相当的ORR催化活性以及优于Pt/C催化剂的OER催化活性和耐久性,有望应用于金属-空气电池、可再生燃料电池等化学电源中,并为鸡蛋黄的高附加值利用提供新的途径。     

氢燃料电池用催化剂的制备和性能研究

氢燃料电池是一种能够将化学能直接转化为电能的能量转化装置,具有转化效率高、清洁环保等优点,被认为是21世纪最有前途的新能源技术。催化剂作为氢燃料电池的关键材料,直接影响电池的使用寿命。通过以炭黑为基体、血晶素为前驱体,通过自组装热解两步法制备复合载体,并负载铂制备Pt/Fe-N-C/EC复合催化剂。考察催化剂的电化学性能,并将其制备成膜电极组装单电池测试电池性能。结果表明,制备的铂炭催化剂具有良好的电化学性能,质量比活性可达183.26 mA·mg^-1,电化学活性面积可达92.79 m²·g^-1,膜电极组装的单池在DOE加速耐久30 000圈实验后,其在0.8 A·cm^-2处电压值衰减18 mV,电化学活性面积衰减37.64%,符合DOE标准。     

选择性氧化脱除甲醇重整氢源中CO的研究

微量CO会使质子交换膜燃料电池(PEMFC)的PtRu/C电极中毒,从而降低燃料电池的性能。本文研究了堇青石蜂窝陶瓷基体涂覆Al_2O_3载体担载Pt、Pd、Ru、Rh等活性组分选择性氧化脱除甲醇重整气中CO的性能,同时研究了Cu、Fe、Sn、Co、La、Ce、Zr等助剂对催化剂性能的影响。结果显示Pt/Al_2O_3整体催化剂能够有效地脱除重整气中的CO,助剂Cu、Fe、Sn、Co的加入使得反应的温度区间向低温移动,其中Co的加入明显提高了CO的转化率和选择性。     

直接甲醇燃料电池阳极催化剂磷化镍的合成及其性能的研究

通过水热反应制备了Ni2P纳米粒子,该Ni2P纳米粒子在碱性溶液中对甲醇的氧化具有良好的催化性能。以Ni2P纳米粒子为阳极催化剂,并以Pt/C为阴极催化剂,搭建了在碱性条件下运行的直接甲醇燃料电池。研究结果显示,以空气为氧化剂,以甲醇为燃料,在常压、室温条件下工作,该碱性燃料电池的输出电流密度为40m A/cm2时,输出比功率为15m W/cm2,从而构建了一种阳极无铂基催化剂的直接甲醇燃料电池。     

IrO2-deposited Pt electrocatalysts for unitized regenerative polymer electrolyte fuel cells

An IrO₂/Pt electrocatalyst for the polymer electrolyte-type unitized regenerative fuel cell (URFC) was prepared by deposition of iridium oxide (IrO₂) particles on Pt black via a colloidal iridium hydroxide hydrate precursor, and URFC performance was examined. After the iridium hydroxide hydrate deposited Pt was calcined at 400 °C in air for 1 h, rutile-structure IrO₂ particles (20–50 nm dia.) were formed on Pt particle clusters. TEM and pore volume distribution analysis revealed that the microstructure of the deposited IrO₂/Pt catalyst was different from the mixed IrO₂/Pt catalyst. The cell using the deposited IrO₂/Pt (20 at % Ir) catalyst showed similar fuel cell performance with the mixed IrO₂/Pt electrode of higher Pt content (10 at % Ir) while maintaining water electrolysis performance. Consequently, 51% round-trip energy conversion efficiency at a current density of 300 mA cm^–2 was attained.     

一体式再生燃料电池性能

报道了反应条件对一体式再生燃料电池单体电池性能的影响,并对单体电池的极化特性和循环稳定性进行测试。结果表明：URFC单体电池表现出优异的电性能和良好的循环稳定性。双模式工作条件下,反应温度控制在60～70 ℃比较合适。在燃料电池模式下,提高氧气压力可以更显著的提高电池性能;在氢气相对湿度为100%条件下,氧气相对湿度对电池性能影响不大,当电流密度大于500 mA/cm²时,采用干态氧气和相对湿度为100%氧气时,电池性能趋于一致。     

Electrochemical performance of Ni/TiO2 hollow sphere in proton exchange membrane water electrolyzers system

This work presents the electrocatalytic evaluation of Ni/TiO₂ hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm^?2 peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO₂ electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm^?2. In the anodic polarization curves, the performance of 15 wt% Ni/TiO₂ hollow sphere electrocatalyst was evaluated up to 140 mA cm^?2 at comparatively lower over-potential value. 20 wt% Ni/TiO₂ hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer.     

Bifunctional electrodes for unitised regenerative fuel cells

The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of unitised regenerative fuel cells (URFC) are reported. Bifunctional oxygen electrodes are important for URFC development because favourable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of catalyst mixtures, multilayer arrangements and segmented configurations with single catalyst areas. Distinct electrochemical behaviour was observed for both modes and can be explained on the basis of impedance spectroscopy. The mixture of both catalysts performs best for the present stage of electrode development. Also, the multilayer electrodes yielded good results with the potential for optimisation. The influence of ionic and electronic resistances on the relative performance is demonstrated. However, penalties due to cross currents in the heterogeneous electrodes were identified and explained by comparing the performance curves with electrodes composed of a single catalyst. Potential improvements for the different compositions are discussed.     

Design,Fabrication and Preliminary Study of a Mini Power Source with a Planar Six‐cell PEM Unitised Regenerative Fuel Cell Stack

A novel micro planar fuel cell power supplier, in which a six‐cell PEM unitised regenerative fuel cell (URFC) stack is used as the power generator, was designed and fabricated. Six membrane electrode assemblies were prepared and integrated on one piece of membrane by spraying catalyst slurry on both sides of the membrane. Each cell was made by sandwiching a membrane electrode assembly (MEA) between two graphite monopolar plates and six cell units were mechanically fixed in two organic glass endplates. When the stack was operated in an electrolysis mode, hydrogen was generated from the splitting of water and stored using a hydrogen storage alloy; conversely, when the stack was operated in fuel cell mode, hydrogen was supplied by the hydrogen storage alloy and oxygen was supplied from air by self‐breathing of the cathode. At room temperature and standard atmospheric pressure, the open‐circuit voltage (OCV) of the system reached 4.9 V, the system could be discharged at a constant current density of 20 mA cm^–2 for about 40 min, and the work voltage was ∼2.9 V. The system showed good stability for 10 charge–discharge cycles.     

Dependence of performance of solid polymer electrolyte fuel cells with low platinum loading on morphologic characteristics of the electrodes

This paper describes the results of transmission electron microscopic, scanning electron microscopic and/or Rutherford backscattering spectroscopic analyses of platinum electrocatalysts supported on carbon, and of low catalyst loading gas-diffusion electrodes used in proton-exchange-membrane (PEM) fuel cells. We looked for correlations between the performance of PEM fuel cells and the morphology of low-catalyst-loading electrodes, taking into account the thickness of the catalyst layers, the crystallite sizes of the platinum electrocatalyst supported on carbon and the increased Pt catalyst content near the front of the electrodes. We reached the conclusion that the use of electrodes with thin catalyst layers (made by using platinum on carbon electrocatalysts with a high Pt/C weight ratio) and with more platinum localized near the front surface had the effect of diminishing the overpotentials in PEM fuel cells.     

Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis

Using a combination of density functional theory (DFT) calculations and an array of experimental techniques including in situ X-ray absorption spectroscopy, we identified, synthesized, and tested successfully a new class of electrocatalysts for the oxygen reduction reaction (ORR) that were based on monolayers of Pt deposited on different late transition metals (Au, Pd, Ir, Rh, or Ru), of which the Pd-supported Pt monolayer had the highest ORR activity. The amount of Pt used was further decreased by replacing part of the Pt monolayer with a third late transition metal (Au, Pd, Ir, Rh, Ru, Re, or Os). Several of these mixed Pt monolayers deposited on Pd single crystal or on carbon-supported Pd nanoparticles exhibited up to a 20-fold increase in ORR activity on a Pt-mass basis when compared with conventional all-Pt electrocatalysts. DFT calculations showed that their superior activity originated from the interaction between the Pt monolayer and the Pd substrate and from a reduced OH coverage on Pt sites, the result of enhanced destabilization of Pt–OH induced by the oxygenated third metal. This new class of electrocatalysts promises to alleviate the major problems of existing fuel cell technology by simultaneously decreasing materials cost and enhancing performance.     

Importance of catalyst stability vis-à-vis hydrogen peroxide formation rates in PEM fuel cell electrodes

The role of catalyst stability on the adverse effects of hydrogen peroxide (H₂O₂) formation rates in a proton exchange membrane fuel cell (PEMFC) is investigated for Pt, Pt binary (PtX, X = Co, Ru, Rh, V, Ni) and ternary (PtCoX, X = Ir, Rh) catalysts supported on ketjen black (KB) carbon. The selectivity of these catalysts towards H₂O₂ formation in the oxygen reduction reaction (ORR) was measured on a rotating ring disc electrode. These measured values were used in conjunction with local oxygen and proton concentrations to estimate local H₂O₂ formation rates in a PEMFC anode and cathode. The effect of H₂O₂ formation rates on the most active and durable of these catalysts (PtCo and PtIrCo) on Nafion membrane durability was studied using a single-sided membrane electrode assembly (MEA) with a built-in reference electrode. Fluoride ion concentration in the effluent water was used as an indicator of the membrane degradation rate. PtIrCo had the least fluorine emission rate (FER) followed by PtCo/KB and Pt/KB. Though PtCo and PtIrCo show higher selectivity for H₂O₂ formation than unalloyed Pt, they did not contribute to membrane degradation. This result is explained in terms of catalyst stability as measured in potential cycling tests in liquid electrolyte as well as in a functional PEM fuel cell.     

质子交换膜燃料电池催化剂性能增强方法研究进展

发展低成本、高性能的燃料电池催化剂是实现燃料电池商业化的关键。目前,铂基催化剂仍是动力燃料电池不可替代的主催化剂。本文综述了最近几年燃料电池催化剂增强方面的研究进展,探讨了新型催化剂材料的设计与制备以及提高催化剂活性或稳定性的方法,包括表面修饰、包覆、合金化、几何与电子结构以及晶体结构的调变、催化剂/载体相互作用等手段。开发高活性和高稳定性的非铂类催化剂是燃料电池催化剂的发展趋势和努力方向。其中,提高非铂燃料电池催化剂可靠性、稳定性和活性,迫切需要在燃料电催化理论、非铂催化剂理性设计、燃料电池水热管理、有序化膜电极等方面取得创新和突破。