燃料电池反应器中过氧化氢的生产——Ⅰ 实验研究

以循环流动的盐酸和硫酸水溶液为电解质,在燃料电池反应器中进行了过氧化氢和电能共生的研究.结果表明,石墨可作为共生的适宜催化剂,生成过氧化氢的电流效率可达42%.氧气分压是影响反应速率的主要因素,pH值对反应速率影响小,但对生成过氧化氢的电流效率影响大,特别是当pH＜1时,随pH值减小,电流效率明显下降.     

Poly(vinyl alcohol)/sulfated β-cyclodextrin for direct methanol fuel cell applications

We report a composite membrane based on poly(vinyl alcohol) and sulfated β-cyclodextrin in this paper. TGA and SEM tests provide direct evidence of the thermal stability and the uniform structure of the composite membranes. The performances of the composite membranes are investigated in terms of swelling behavior, methanol permeability and proton conductivity as function of sulfated β-cyclodextrin content. We find that the introduction of sulfated β-cyclodextrin can reduce water uptake. The temperature dependence of proton conductivity reveals that the proton conducting activation energy of the composite membranes is similar to that of Nafion 115, in other words, both the vehicle and Grotthus mechanisms are assumed to be responsible for the composite membranes’ proton transfer. Methanol permeability decreases as the methanol feed concentration increases from 2 M to 20 M. Both proton conductivity and methanol permeability increases with increasing sulfated β-cyclodextrin. The selectivity of the composite membranes defined as the ratio of proton conductivity to methanol permeability obtains the maximum of 1.710 × 10⁴ S s cm⁻³ at the composition of 17 wt.% sulfated β-cyclodextrin. The MEAs fabricate with these membranes are tested, no distinct change occurred to the composite membranes after the MEAs operating for 288 h. These data indicates the chemical and electrochemical stability of the membranes and their potential application in direct methanol fuel cells.     

High efficiency process for the production of pure oxygen based on solid oxide fuel cell–solid oxide electrolyzer technology

This paper presents a novel system for production of pure oxygen based on the integration of a solid oxide fuel cell (SOFC) and a solid oxide electrolyzer (SOEC). In the proposed arrangement, the SOFC provides electricity, heat and H₂O in vapour phase to the SOEC which carries out the inverse reactions of the SOFC, that is the separation of H₂O into H₂ (used as a fuel for the SOFC) and O₂ (representing the yield of the system). Simulations carried out in different operating conditions show that when the integrated SOFC–SOEC device runs at low current densities (less than 1000 A m⁻²), pure oxygen can be generated with an electric consumption comparable to mid-size cryogenic air separation units, and significantly lower than small scale systems based on the PSA technology.     

Prediction of the effective coefficient of thermal expansion of heterogeneous media using two-point correlation functions

Statistical continuum mechanics is used to predict the coefficient of thermal expansion (CTE) for solid oxide fuel cell glass-ceramic seal materials with different morphology and crystallinity. Two-point correlation functions are utilized to represent the heterogeneous microstructure morphology and phase distribution. The model uses two-point correlation functions in conjunction with local properties to predict the effective CTE. Prediction results are comparable to experimental CTE results. The advantage of using the statistical continuum mechanics model in predicting the effective properties of anisotropic media is shown, using the ability to take the microstructure into consideration.     

A self-pumping and self-breathing micro direct methanol fuel cell with polymer bipolar plates

A passive micro direct methanol fuel cell (DMFC) for reducing volume and parasitic power is designed and fabricated using several integrated technologies. New bipolar plates with tapered channels at the anode and a pillar array at the cathode are first applied to a passive micro-DMFC. The substrate of the bipolar plates made of acrylonitrile butadiene styrene (ABS) is hot embossed with two molds, fabricated by UV-LIGA and micro machining. To make the bipolar plates conductive and hydrophilic, a nickel layer is electroplated on the ABS plates, and three PDDA/PSS bi-layers are self-assembled onto the nickel layer. The bipolar plates are produced using hot embossing, a low cost, highly accurate batch process. A single cell is assembled to verify the self-pumping function, and it can generate a peak power density of 7.4 mW cm⁻² with a 3 M methanol solution. The fuel cell is verified to work in three different orientations. When the fuel cell is placed horizontally, the self-pumping rate is about 0.1-0.15 mL h⁻¹. And the fuel cell can work through self-pumping for 5 h under this condition.     

Tetrabutyl-tetraphenyl-diindenoperylene derivatives as alternative green donor in bulk heterojunction organic solar cells

We present the material 2,3,10,11-tetrabutyl-1,4,9,12-tetraphenyl-diindeno[1,2,3-cd:1′,2′,3′-lm] perylene (Bu4-Ph4-DIP) as alternative green donor for bulk heterojunction small molecule organic solar cells (SMOSC). It is shown that Bu4-Ph4-DIP exhibits suitable absorption characteristics to be a potential material to fill the absorption gap between the commonly used standard absorbers ZnPc and C₆₀.Devices with bulk heterojunctions of Bu4-Ph4-DIP:C₆₀ display very high open circuit voltages of 0.99 V, high fill factors of up to 57%, and experiments yield promising efficiencies of η>2%. Such green-blue absorbing SMOSC are characterized by current voltage and external quantum efficiency measurements, and material properties are studied. It is shown that the devices are responsive to substrate heating, and that different donor-acceptor mixing ratios can increase device performance. Possible influences of mixing ratio and heating on device morphology and electrical properties are discussed.     

The ability of zinc to inhibit the sporulation and viability of Clostridium sporogenes and growth of other bacteria

The objective of this study was to investigate the influence of zinc on the sporulation and viability of Clostridium sporogenes and on the growth of other bacteria. When 0.5% ZnCl₂ was added to a sporulation medium, it completely inhibited C. sporogenes (PA 3679) sporulation for up to 3 weeks. At concentrations of 0.5% and 1.0%, ZnCl₂ not only completely inactivated the vegetative cell viability (>7.0 Log reduction) but also significantly reduced the spore viability (<2.1 Log reduction) of C. sporogenes. Taken together, it was concluded that zinc blocks C. sporogenes sporulation by damaging (or killing) vegetative cells and probably by interfering with the biosynthesis of spore components. In addition to the inhibitory effect on the sporulation and viability of C. sporogenes, ZnCl₂ was found to have a broad antimicrobial spectrum against all Gram‐positive and Gram‐negative spoilage and pathogenic bacteria tested. The minimal inhibitory concentration for inhibiting the bacteria ranged between 3.7 and 7.4 mm . Therefore, we expect that this compound or a combination thereof has a potential as a surface‐cleaning agent or disinfectant.     

A branch and bound enhanced genetic algorithm for scheduling a flowline manufacturing cell with sequence dependent family setup times

This paper addresses the permutation flowline manufacturing cell with sequence dependent family setup times problem with the objective to minimize the makespan criterion. We develop a cooperative approach including a genetic algorithm and a branch and bound procedure. The latter is probabilistically integrated in the genetic algorithm in order to enhance the current solution. Moreover, the application of the branch and bound algorithm is based upon the decomposition of the problem into subproblems. The performance of the proposed method is tested by numerical experiments on a large number of representative problems.     

The effect of rear surface polishing to the performance of thin crystalline silicon solar cells

As the thickness of crystalline silicon solar cells decreases, light loss cannot be avoided due to the absorption limit in long wavelength light. Internal rear side reflection can be enhanced by polishing the rear surface. The rear polishing processes are performed before the texturing and before and after doping the emitter layer to optimize the solar cell fabrication process sequences. All cells made by rear surface polishing showed improved light trapping in long wavelength region (900-1100 nm) compared to that in the conventional cells. However, silicon solar cells fabricated by rear polishing before and after doping have similar (35.5 mA/cm²) or lower (35.26 mA/cm²) short circuit current density compared to the cells produced by the conventional process (35.59 mA/cm²) due to pore damage to the anti-reflection layer and the surface of the emitter layer during rear polishing. This surface damage was effectively prevented adapting the rear surface polishing before the front surface texturing, which led to increasing the current density from 35.59 to 36.29 mA/cm².     

Microstructure and mechanical properties of aluminum back contact layers

The overall demand to reduce solar energy costs gives a continuous drive to reduce the thickness of silicon wafers. Handling and bowing problems associated with thinner wafers become more and more important, as these can lead to cells cracking and thus to high yield losses. In this paper the microstructure and mechanical properties of the aluminum on the rear side of a solar cell are discussed. It is shown that the aluminum back contact has a complex composite-like microstructure, consisting of five main components: (1) the back surface field layer; (2) a eutectic layer; (3) spherical (3-5 μm) hypereutectic Al-Si particles surrounded by a thin aluminum oxide layer (200 nm); (4) a bismuth-silicate glass matrix; and (5) pores (14 vol%). The Young’s modulus of the Al-Si particles is estimated by nanoindentation and the overall Young’s modulus is estimated on the basis of bowing measurements. These results are used as input parameters for the improved thermomechanical multiscale model of a solar cell.