Transforming liquid flow fuel cells to controllable reactors for highlyefficient oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid at low temperature

Highly-efficient oxidation of 5-hydroxymethylfurtural(HMF) to 2,5-furandicarboxylic acid(FDCA) at low temperature with air as the oxidant is still challenging.Herein,inspired by the respirato ry electron transport chain(ETC) of living cells mediated by electron carriers,we constructed artificial ETCs and transformed liquid flow fuel cells(LFFCs) to flexible reactors for efficient oxidation of HMF to produce FDCA under mild conditions.This LFFC reactor employed an electrodeposition modified nickel foam as an anode to promote HMF oxidation and(VO_(2))_(2)SO_(4) as a cathode electron carrier to facilitate the electron transfer to air.The reaction rate could be easily controlled by selecting the anode catalyst,adjusting the external loading and changing the cathodic electron carrier or oxidants.A maximal power density of 44.9 mW cm^(-2) at room temperature was achieved,while for FDCA production,short-circuit condition was preferred to achieve quick transfer of electrons.For a single batch operation with 0.1 M initial HMF,FDCA yield reached 97.1%.By fed-batch operation,FDCA concentration reached 144.5 g L^(-1) with a total yield of 96%.Ni^(2+)/Ni^(3+) redox couple was the active species mediating the electron transfer,while both experimental and DFT calculation results indicated that HMFCA pathway was the preferred reaction mechanism.

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative analysis.Herein,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC anodes.The lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was performed.Two samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging process.Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell.The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged cell.The microstructural and activity de-gradations are attributed to Ni migration and coarsening.

Correlation between hydration properties and electrochemical performances on Ln cation size effect in layered perovskite for protonic ceramic fuel cells

PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.

Promoting and controlling electron transfer of furfural oxidation efficiently harvest electricity,furoic acid,hydrogen gas and hydrogen peroxide

Conventional chemical oxidation of aldehydes such as furfural to corresponding acids by molecular oxygen usually needs high pressure to increase the solubility of oxygen in aqueous phase,while electrochemical oxidation needs input of external electric energy.Herein,we developed a liquid flow fuel cell(LFFC)system to achieve oxidation of furfural in anode for furoic acid production with co-production of hydrogen gas.By controlling the electron transfer in cathode for reduction of oxygen,efficient generation of electricity or production of H_(2)O_(2)were achieved.Metal oxides especially Ag_(2)O have been screened as the efficient catalyst to promote the oxidation of aldehydes,while liquid redox couples were used for promoting the kinetics of oxygen reduction.A novel alkaline-acidic asymmetric design was also used for anolyte and catholyte,respectively,to promote the efficiency of electron transfer.Such an LFFC system achieves efficient conversion of chemical energy of aldehyde oxidation to electric energy and makes full use the transferred electrons for high-value added products without input of external energy.With(VO_(2))_(2)SO_(4)as the electron carrier in catholyte for four-electron reduction of oxygen,the peak output power density(Pmax)at room temperature reached 261 mW/cm^(2)with furoic acid and H_(2)yields of 90%and 0.10 mol/mol furfural,respectively.With anthraquinone-2-sulfonate(AQS)as the cathodic electron carrier,Pmaxof 60 mW/cm^(2)and furoic acid,H_(2)and H_(2)O_(2)yields of 0.88,0.15 and 0.41 mol/mol furfural were achieved,respectively.A new reaction mechanism on furfural oxidation on Ag_(2)O anode was proposed,referring to one-electron and two-electron reaction pathways depending on the fate of adsorbed hydrogen atom transferred from furfural aldehyde group.

Cashew Nut Shell Liquid(CNSL)Based Bio-Derived Resin And Composites for Advanced Structural,Automotive,Electronic Packaging and Medical applications-A Review

As India is a world class producer of sugarcane,sugar beet,other tubers like potato and vegetables with starch,cashew and badam,castor oil and soybean,the quantum of bio resins and bio plastics that can be produced from these conventional,organic and genetically modified plants is immense.As on date,advanced and state of the art plastics and composites are being used in many applications as there is no incentive for farmers to produce plants and vegetables for the plastics and resins market exclusively.The use of advanced composites in varied applications escalates costs and shifts the material consumption that would deplete the natural resources,through excessive usage at one end and lack of demand for natural resources at the other end as bio derived composites become under-utilized.This review paper attempts to project the actual possibilities of the bio resin and bio plastic market in this country and provides the knowhow for the production of bio-phenolic cashew nut shell resin which are more than a substitute for the synthetically produced epoxies.Their true potentialities in composites product applications involving structural,thermal,electronic,pharmaceutical and petroleum engineering markets is discussed in this paper.A novel working model with an economically feasible option is also provided for those concerned about their safe disposal,recycling,reuse and conversion into useable fuel with virtually no impact to the environment.Cashew Nut Shell Liquid(CNSL)is an abundant natural source for synthesizing phenolic compounds.The excellent monomer,Cardanol is isolated from CNSL for polymer production.These are polymerized with aldehydes and acids at a particular mole fraction in the presence of catalysts like alkalis to convert into rigid resins.Differential Scanning Calorimetric(DSC)and Thermo Gravimetric Analysis(TGA)were studied for the thermal characterization of the synthesized CNSL Resins.Characterization of the synthesized resins was also carried out with respect to the evaluated mechanical properties such as hardness,strength,elastic modulus and fracture toughness.The synthesized CNSL resins yielded many interesting compositions with varied properties increasing the possibilities of various resin formulations which could be used for composites applications in vibrational damping.The electronic packaging applications of nano-composites with high dielectric strength produced with the CNSL matrix are also highlighted.

欧洲汽车动力系统多元化的发展趋势和展望

当前,全球能源结构处在变革时期,低碳和零碳化是包括汽车行业在内的所有经济运行和规划活动中的重中之重。汽车动力系统的能源呈现多元化的发展趋势,始于轻型车的电动化已成为不可逆转的总体方向,而氢时代在到来之前面临各种技术和非技术类等诸多问题的挑战。电动化带来的一个更为广泛应用的新技术是人工智能(AI),从而使得汽车动力系统逐步突破传统设计方法的局限得以适应更加复杂的环境条件并获得高效率。该文介绍欧洲汽车动力系统电动化和多元化的发展趋势,针对欧盟正在考虑中的电力合成燃料等问题并结合动力系统智能化等发展趋势,对欧洲汽车技术领域在2035年前的研发动向作出相关思考以及展望。

基于金字塔池化网络的质子交换膜燃料电池气体扩散层组分推理方法

针对质子交换膜燃料电池气体扩散层(gas diffusion layer composition,GDL)形貌划分与制备工艺改进问题,提出了一种基于金字塔池化网络(pyramid scene parsing network,PSPNet)与多层感知器(multi-layer perception,MLP)的气体扩散层组分识别与比例推理方法:首先将带标签的气体扩散层扫描电镜(scanning electron microscope,SEM)图片输入神经网络,得到特征图;得到的图像特征层进入金字塔池化模块后,获取SEM图像的深层和浅层特征;随后将深层和浅层特征图层融合输入全卷积网络(fully convolutional network,FCN)模块,得到预测图像;最后统计各个组分上的像素点比例,通过MLP完成组分比例推理。结果表明:所提方法组分识别像素准确率达81.24%;在5%偏差范围内,比例推理准确率为88.89%。该方法解决了气体扩散层多组分无法区分、比例无法获知的问题,可有效应用于气体扩散层的质检、数值重构以及制备工艺改进。

氮掺杂多孔碳材料阳极制备及其在微生物燃料电池上的应用

微生物燃料电池(MFCs)作为一种可以替代传统能源的生物电化学系统引起研究者的极大兴趣,其阳极材料的构造是目前的研究热点.本文从改善阳极材料表面物理化学性质的角度出发,用吐司作为多孔碳前驱体,三聚氰胺为氮源,直接烧制氮掺杂三维碳材料,并与不添加氮源的阳极材料和未改性的商用碳布进行比较.制备的掺氮NB1000阳极具有较大的比表面积(216.664 m^(2)·g^(-1))和优良的电导率.利用Geobacter和Shewanella混合菌落在微生物燃料电池(MFCs)中进行培养和性能评价,NB1000阳极的微生物燃料电池最大面功率密度为3049.714 mW·m^(-2),电流密度为7.4464 A·m^(-2),分别是普通碳布阳极的6.54倍和1.54倍.结果表明,NB1000作阳极的MFCs具有较高的功率密度,主要归因于阳极中引入氮掺杂,促进了产电微生物胞外电子传递过程所需的外膜c型细胞色素OmcA和MtrC的分泌.

不同焊接方法下燃料元件包壳用ODS钢焊接接头界面演化规律

ODS钢具有优异的高温力学性能、抗辐照性能和抗热蠕变性能等,是最有潜力的下一代核反应堆包壳候选材料之一。ODS钢的焊接技术主要包括熔焊、钎焊、压力焊等,根据核燃料元件包壳结构,选择电子束焊接、旋转摩擦焊及脉冲电流辅助扩散焊三种焊接方法进行对比研究,并对ODS钢焊接接头微观形貌演化进行分析,揭示了最优焊接方法及界面形貌演化规律。结果表明,电子束焊接及旋转摩擦焊接工艺下,焊接接头的晶界处均有Y_(2)O_(3)析出,而采用脉冲电流辅助扩散焊无氧化物析出和团聚,对于Fe-Cr系ODS钢有突出优势。因此,脉冲电流辅助扩散焊在抑制ODS钢中纳米氧化物的析出、团聚和减少接头变形等方面具有显著优势,是一种适合ODS钢焊接的高质量焊接方法。

基于实测载荷的牵引车双腔油箱失效研究

针对某牵引车双腔油箱内部实心隔板结构失效且载荷不易获取、量化等问题,提出了一种基于实测载荷的油箱失效研究方法。使用扫描电镜对样件断口进行观测分析,确定失效模式为疲劳失效;基于燃油的力学特性分析,双腔油箱失效主要原因是由单阻尼挡板提供的晃动阻尼不足,导致实心隔板受到冲击力过大;增加多孔阻尼挡板,可降低行车过程中燃油晃动对实心隔板的冲击力,对油箱进行结构优化;油箱优化前、后关键位置安装了传感器,在试验场进行双腔油箱优化前、后两种状态下实心隔板应变载荷采集,对载荷数据进行幅值、雨流及统计分析,对优化前、后油箱实测载荷进行量化分析,优化后载荷最大幅值下降比例超过60%,表明增加阻尼挡板可显著减小实心隔板受到的冲击载荷;优化后试验场路试未出现油箱失效问题,表明优化后实心隔板应变载荷低于油箱的疲劳极限,提高了油箱实心隔板的疲劳寿命;油箱结构优化后满足安全需求,为产品后续优化和下一代新产品开发提供理论指导和数据依据。

电子浓缩富集气相色谱法测定燃料氢中甲醛

氢燃料电池是未来新能源发展的主要方向。甲醛是燃料氢中的杂质组分之一,对燃料电池有毒化作用,因此准确测定燃料氢中甲醛含量是极为重要的工作。本文基于电子预浓缩富集气相色谱脉冲氦离子检测器建立了可用于氢中甲醛的检测方法。用高纯氢气稀释甲醛模拟燃料氢中甲醛检出限测定,分别探究了浓缩体积、本底吹扫时间、解析吹扫时间、解析温度和解析时间对甲醛出峰的影响,得到最优分析条件。采用优化后的条件对甲醛标准物质进行检测,结果表明,甲醛检出限为0.03 ppm, RSD为3%。该方法避免了人为干扰,具有良好的重复性,为燃料氢中甲醛测定提供了可靠的技术手段。

电控正流量挖掘机泵控特性分析

基于电控正流量系统控制原理,建立控制方程,分析其泵控特性。为对比其与负流量、液控正流量系统挖掘机整机性能差异,进行相关试验研究。试验结果表明:电控正流量系统性能最优越,其动臂提升加回转时间为4.07 s,较液控正流量系统缩短5.79%;液压缸行程百分比为73.52%,较液控正流量增大5.04%;铲斗离地高度为2 988 mm,较液控正流量增大9.89%;而负流量系统各工作装置速度均小于液控正流量、电控正流量系统。负流量、液控正流量与电控正流量系统行驶、回转速度与设计值基本一致,控制方式对其影响较小,但电控正流量跑偏量较小并且各模式一致性好,制动时间、制动角度最小,回转制动性能优越。此外,电控正流量系统挖掘效率为302.4 m~3/h,较液控正流量系统提高6.33%,较负流量系统提高14.03%;挖掘油耗为27.8 L/h,较液控正流量降低13.66%,较负流量降低20.80%。结合经济性、可靠性,电控正流量为最优的泵控系统。

Power Conversion System Strategies for Fuel Cell Vehicles

Power electronics is an enabling technology for the development of environmental friendly fuel cell vehicles, and to implement the various vehicle electrical architectures to obtain the best performance. In this paper, power conversion strategies for propulsion and auxiliary power unit applications are described. The power electronics strategies for the successful development of the fuel cell vehicles are presented. The fuel cell systems for propulsion and for auxiliary power unit applications are also discussed.

Recent Progress in Heavy Fuel Aviation Piston Engine

Heavy fuel aviation piston engines(HF-APEs)refer to the engine using fuels with high flash point,such as kerosene or light diesel.Here technique specifications of some classical foreign HF-APEs(Hirth3503,Zanzottera 498)are introduced.Recent progress and trend of fuel injection,fuel ignition,working cycle,intake charging,thermal management and electronic control of HF-APE are compared and summarized.Emphases are put on the technological difficulties,solutions and development tendency in the design,retrofitting and manufacturing of HF-APE aiming to provide references for the research of related area and the development of prototype HF-APE in China.

Mechanism of Simultaneous Nitrogen Removal and Electricity Generation by Microbial Fuel Cell

The working mechanism of MFC used for simultaneous nitrogen removal and electricity generation was studied.The results show that the electrode biofilms and suspension had different modes of electron transfer.The microorganisms growing on the electrodes and bioflocs could transfer electrons by direct contact and intermediaries respectively.The electrode biofilms and bioflocs were dominant in different functional spaces,and played a synergistic role in the process of contaminant removal,but showed a certain competitive relationship in the process of electricity generation.This study can provide a theoretical basis for the development of a new low-consumption wastewater treatment technology and promote technological innovation in wastewater treatment.

Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells

The variation of the three-dimensional(3D)structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support.The increasing degradation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells(PEM-FCs).This phenomenon can be explained by performing 3D tomographic analysis at the nanoscale.However,conventional tomographic approaches which present limited experimental feasibility,cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far.Therefore,a reliable methodology is required for the 3D geometrical evaluation of the carbon structure.Here,we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution.This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area,pore size distribution,and their 3D networking.These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation.This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the development of stable PEM-FC electrodes.

Coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion with molybdovanadophosphoric heteropolyacids as anode electron transfer carriers

Owing to their acidity,oxidizing ability and redox reversibility,molybdovanadophosphoric heteropolyacids(H_(n+3)PMo_(12-n)VnO40,abbreviated as PMo_(12-n)Vn) were employed as electron transfer carriers for coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion.In this novel coupled process,PMo_(12-n)Vn pretreatment that causes deconstruction of cell wall structure with PMo_(12-n)Vn being simultaneously reduced can be considered as the "charging" process.The reduced PMo_(12-n)Vn are further re-oxidized with release of electrons in a liquid flow fuel cell(LFFC) to generate electricity is the "discharging" process.Several Keggin-type PMo_(12-n)Vn with different degree of vanadium substitution(DSV, namely n) were prepared.Compared to Keggin-type phosphomolybdic acid(PMo_(12)),PMo_(12-n)Vn(n=1-6) showed higher oxidizing ability but poorer redox reversibility.The cellulose enzymatic digestibility of PMo_(12-n)Vn pretreated wheat straw generally decreased with increase in DSV, but xylan enzymatic digestibility generally increased with DSV.PMo_(12) pretreatment of wheat straw at 120℃ obtained the highest enzymatic glucan conversion(EGC) reaching 95%,followed by PMo11V1 pretreatment(85%).Discharging of the reduced heteropolyacids in LFFC showed that vanadium substitution could improve the maximum output power density(Pmax).The highest Pmax was obtained by PMo9 V3(44.7 mW/cm^(2)) when FeCl_(3) was used as a cathode electron carrier,while PMo_(12) achieved the lowest Pmax(27.4 mW/cm^(2)).All the heteropolyacids showed good electrode Faraday efficiency(>95%) and cell discharging efficiency(>93%).The energy efficiency of the coupled process based on the heat values of the products and generated electric energy was in the range of 18%-25% depending on DSV.PMo_(12) and PMo11V1 seem to be the most suitable heteropolyacids to mediate the coupled process.

Carbon material-based anodes in the microbial fuel cells

For the performance improvement of microbial fuel cells(MFCs),the anode becomes a breakthrough point due to its influence on bacterial attachment and extracellular electron transfer(EET).On other level,carbon materials possess the following features:low cost,rich natural abundance,good thermal and chemical stability,as well as tunable surface properties and spatial structure.Therefore,the development of carbon materials and carbon-based composites has flourished in the anode of MFCs during the past years.In this review,the major carbon materials used to decorate MFC anodes have been systematically summarized,based on the differences in composition and structure.Moreover,we have also outlined the carbon material-based hybrid biofilms and carbon material-modified exoelectrogens in MFCs,along with the discussion of known strategies and mechanisms to enhance the bacteria-hosting capabilities of carbon material-based anodes,EET efficiencies,and MFC performances.Finally,the main challenges coupled with some exploratory proposals are also expounded for providing some guidance on the future development of carbon material-based anodes in MFCs.