Novel multilayer Nafion/SPI/Nafion composite membrane for PEMFCs

A novel multilayer membrane for the proton exchange membrane fuel cell (PEMFC) was developed. Nafion was dispersed uniformly onto both sides of the sulfonated polyimide (SPI) membrane. The Nafion/SPI/Nafion composite membrane was prepared by immersing the SPI into the Nafion-containing casting solution. Through immersing both membranes into the Fenton solution at 80 °C for 0.5 h for an accelerated ex situ test, chromatographic analysis of the water evacuated from the cathode and the anode of the cells and a durability test of a single proton exchange membrane fuel cells, it was proved that the stability of the composite membrane has been greatly improved by adding the Nafion layer compared with the SPI membrane. The fuel cell performance with the SPI and Nafion/SPI/Nafion membranes was similar to the performance with the commercial product Nafion^® NRE-212 membrane at 80 °C.     

Synthesis and characterization of sulfonated poly(arylene ether ketone ketone sulfone) membranes for application in proton exchange membrane fuel cells

A series of sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS) copolymers were synthesized by nucleophilic polycondensation. The copolymers exhibit good thermal and oxidative stabilities, all the SPAEKKS copolymers can be cast into tough membranes. Ionic exchange capacities (IEC), water uptake properties, thermal stabilities, methanol diffusion coefficients and proton conductivities were thoroughly studied. Also the microstructures of the membranes were investigated by TEM. The proton conductivity of the SPAEKKS-4 membrane is close to that of Nafion-117 at 80 °C. The methanol diffusion coefficient of the membrane is much lower than that of Nafion-117 under the same testing conditions. The SPAEKKS membranes are promising in proton exchange membranes fuel cell (PEMFC) application.     

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.     

双染料共敏化的纳米晶二氧化钛多孔电极的光伏特性研究

通过化学吸附方法，在二氧化钛多孔电极上修饰甲基卟啉和酞菁锌两种染料，制备出双染料／ＴｉＯ２电极。酞菁和卟啉在可见光区有不同的吸收范围，它们共同修饰可使ＴｉＯ２电极在可见光区的光谱吸收和光电流响应具有较宽的范围，可提高对太阳光的利用率，改善电极的光电转换特性。     

α—CuPc／PVK薄膜中的高斯分布陷阱

对α-CuPc/PVK薄膜的等温衰减电流谱作了进一步的分析,得到了两个交叠的高斯分布型陷阱。其陷阱能级深度分别为0.14和0.17eV,分布宽度σ为0.021和0.0019eV,陷阱的态密度 H_1均在10~(18)cm~(-3)数量级.     

On the correlation between morphology and electronic properties of copper phthalocyanine (CuPc) thin films

The morphology of vacuum deposited copper phthalocyanine (CuPc) thin films surface deposited on Si(111) have been studied using the contact mode Atomic Force Microscope (AFM). The influence of substrate temperature during deposition and of the post-deposition UHV annealing on surface roughness as well as on the average and maximum grain height was determined. The observed changes of surface morphology were in a good correlation with the shift of surface Fermi level position in the band gap after O₂ exposure determined in our recent photoemission studies.     

光存储酞菁薄膜的加速老化研究

采用加速老化试验对光存储酞菁薄膜进行了寿命研究，以反射率的变化作为试验的判断依据。在５５℃，８５％ＲＨ；６５℃，８５％ＲＨ和７５℃，８５％ＲＨ的条件下，测试了反射率随时间的变化关系，用外推法估算出光存储酞菁薄膜的自然寿命。     

萘磺化反应体系中硫酸含量与反应产物的分析

分析了萘磺化反应体系中硫酸含量与萘磺化反应进程的关系，提出以酸碱滴定法测定体系中硫酸含量来精确分析磺化反应进程的方法。     

Comparative study on carbon cathodes with and without cobalt phthalocyanine in Li/(SOCl2 + BrCl) cells

The comparative study of carbon cathodes with and without cobalt phthalocyanine (CoPc) in BCX cells (the Li/SOCl₂ cell containing BrCl in the electrolyte) has been carried out by using electrochemical impedance spectroscopy (EIS), constant current discharge curves, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. It is shown that CoPc can improve both the capacity and the voltage of discharge for the BCX cell, and enhance the stability of the open-circuit voltage of the BCX cell. The addition of CoPc to carbon cathode of BCX cells can also decrease the impedance value of the porous carbon cathode, resulting in the considerable decrease of both film resistance and electron transfer resistance. The microstructure and composition of the discharge products on carbon cathodes have been studied using SEM/EDS and XPS analysis.     

The effect of central metal atom on the electrical properties of phthalocyanine macromolecule

In order to investigate the effect of the central metal atom variation on the electrical properties of phthalocyanine macromolecule, iron, cobalt, nickel and copper as the di-valent metals were incorporated into the macrocycle. The electrical properties of these metallophthalocyanines were then studied to establish a structure-property relation-ship. The experimental data show that electrical parameters are greatly influenced by the choice of metal atom. It remains to be investigated whether results are dominantly interpretable in terms of the size of the metal, intermolecular π-electron delocalization of the macrocycle, or other molecular orbital property.