Dual‐Doped Molybdenum Trioxide Nanowires: A Bifunctional Anode for Fiber‐Shaped Asymmetric Supercapacitors and Microbial Fuel Cells

A novel in situ N and low‐valence‐state Mo dual doping strategy was employed to significantly improve the conductivity, active‐site accessibility, and electrochemical stability of MoO₃, drastically boosting its electrochemical properties. Consequently, our optimized N‐MoO_3?x nanowires exhibited exceptional performances as a bifunctional anode material for both fiber‐shaped asymmetric supercapacitors (ASCs) and microbial fuel cells (MFCs). The flexible fiber‐shaped ASC and MFC device based on the N‐MoO_3?x anode could deliver an unprecedentedly high energy density of 2.29 mWh cm^?3 and a remarkable power density of 0.76 μW cm^?1, respectively. Such a bifunctional fiber‐shaped N‐MoO_3?x electrode opens the way to integrate the electricity generation and storage for self‐powered sources.     

An Aurivillius Oxide Based Cathode with Excellent CO2 Tolerance for Intermediate‐Temperature Solid Oxide Fuel Cells

The Aurivillius oxide Bi₂Sr₂Nb₂MnO_12?δ (BSNM) was used as a cobalt‐free cathode for intermediate‐temperature solid oxide fuel cells (IT‐SOFCs). To the best of our knowledge, the BSNM oxide is the only alkaline‐earth‐containing cathode material with complete CO₂ tolerance that has been reported thus far. BSNM not only shows favorable activity in the oxygen reduction reaction (ORR) at intermediate temperatures but also exhibits a low thermal expansion coefficient, excellent structural stability, and good chemical compatibility with the electrolyte. These features highlight the potential of the new BSNM material as a highly promising cathode material for IT‐SOFCs.     

Influence of Metal Oxides on Platinum Activity towards Methanol Oxidation in H2SO4 solution

Pt–CeO₂/C, Pt–TiO₂/C, and Pt–ZrO₂/C electrocatalysts were prepared by using a modified microwave‐assisted polyol process. Physical characterization was performed by using XRD, TEM, and EDX analyses. The incorporation of different metal oxides increased the dispersion degree of Pt nanoparticles and reduced their diameter to 2.50 and 2.33 nm when TiO₂ and ZrO₂ were introduced to Pt/C, respectively. The electrocatalytic activity of various electrocatalysts was examined towards methanol oxidation in H₂SO₄ solution by using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Among the studied composites, Pt–ZrO₂/C was selected to be a candidate electrocatalyst for better electrochemical performance in direct methanol fuel cells.     

Methods for the characterization of Jet Propellent-8: vapor and aerosol

Jet Propellant‐8 (JP‐8) has been responsible for the majority of reported chemical exposures by the US Department of Defense. Concerns related to human exposure to JP‐8 are relatively new; therefore, there is a lack of literature data. Additionally, health effects related to the composition of the exposure have only recently been considered. Two major questions exist: (1) what is the compositional difference between the aerosol and vapor portions of JP‐8 under controlled conditions and (2) what is the most representative method to sample JP‐8 aerosol and vapor? Thirty‐seven standards, representing more than 40% of the mass of JP‐8, were used for characterization of the neat fuel, vapor and aerosol portions. JP‐8 vapor samples at a concentration of 1600 mg/m³ were prepared in Tedlar bags. A portion of the vapor samples was adsorbed on charcoal, Tenax and custom mixed phase sorbents. These samples were then extracted using organic solvent and analyzed using gas chromatography/mass spectrometry. The vapor samples extracted from the sorbent tubes were directly compared with a vapor bag. The samples collected using Tenax sorbent tubes were found to be most representative of the composition of the vapor bags. In another set of experiments, aerosolized JP‐8 was generated using a collision nebulizer. Aerosol samples were collected and the chemical composition was characterized. The entire aerosol distribution was collected on a glass filter, extracted into solvent, and analyzed by GC‐MS. Finally, the composition of the vapor and aerosol was compared. The vapor was found to represent the lower molecular weight components of JP‐8, while the aerosol was composed of higher molecular weight components. Therefore, the vapor and aerosol should be treated as two discrete forms of exposure to JP‐8. Copyright © 2007 John Wiley & Sons, Ltd.     

Nitrogen-rich Graphdiyne Film for Efficiently Suppressing the Methanol Crossover in Direct Methanol Fuel Cells

The inhibition of the methanol crossover is one of the intractable challenges in the direct methanol fuel cell.The graphdiyne(GDY)with atomic-level pores shows great potential in realizing the zero-permeation of methanol molecules.In this paper,an ultrathin layer of nitrogen-rich GDY film with a high nitrogen content is largely prepared and readily used for retarding the methanol permeation in the state-of-the-art commercial Nafion membrane.The high N-content in this porous GDY nanofilm remarkably increases the selective suppression in methanol transfer,and single-layer GDY film can efficiently prevent 43％methanol crossover and the value of the double-layer GDY film can be high up to 69％.The power performance and the long-term stability of the cell are obviously improved due to the reduced methanol crossover.     

电催化剂纳米碳基载体的研究进展

质子交换膜燃料电池(PEMFCs)因具有工作温度低、结构紧凑、无腐蚀、启动快和灵活性好等优点,受到人们广泛关注.但其工作时动力学迟缓且易受CO毒化影响,往往需要负载Pt等贵金属催化剂,导致PEMFCs的成本高昂,阻碍了其商业化应用.为提高Pt贵金属的利用率,通常将Pt负载在载体材料上来提高Pt的分散性以减少Pt颗粒集聚,因此,合适的载体材料对于降低PEMFCs成本具有极大意义.纳米碳材料由于具有高稳定性、可控的孔结构、可变的物理形态、可修饰的表面化学以及低成本等特点,是一种理想的催化剂载体材料,已被广泛应用于PEMFCs电催化剂中.本文综述了PEMFCs电催化剂的纳米碳基载体的最新研究进展,重点讨论了纳米碳的纳米结构和表面物理化学性质对电催化剂性能的影响,主要从孔结构、杂原子掺杂以及功能性碳基载体方面对其进行概述.在孔结构方面,纳米碳载体的孔形貌和孔径大小能够显著地影响PEMFCs电催化剂的催化性能.相比于无序孔,有序孔能够减小反应物分子的传质阻力,可使反应物分子更好地与载体孔道内的催化活性位点结合,增加Pt催化剂的可及性,从而提高反应活性.合适的孔径不仅能够使纳米碳载体具有足够的传质通道,还能提供充足的用于电催化反应的高比表面积,从而增加电催化剂的催化性能.在杂原子掺杂方面,向纳米碳载体中掺入氮、硫和磷等杂原子能够稳定碳载体结构,并增加载体表面与金属纳米粒子之间的结合位点,提高金属纳米颗粒的分散性,通过金属-载体之间的相互作用和协同作用提升电催化剂性能.在功能性碳载体方面,通过对纳米碳载体进行有针对性地改性得到具有特定功能的碳化物载体,改性后的功能性碳化物载体能够通过加速CO反应中间体氧化以增加电催化剂的抗CO毒化能力,并能够通过降低燃料电池腐蚀电流的方式提升电催化剂的耐久性.本文讨论了纳米碳载体的最新进展,指出PEMFC电催化剂载体的未来发展方向,为PEMFC催化剂的未来研究和设计提供参考意见,为推动PEMFC的市场化提供帮助.     

可用作便携式电源的高性能直接碳固体氧化物燃料电池组

A direct carbon solid oxide fuel cell (DC-SOFC) stack was prepared with 3 tubular cells electrically connected in series. To increase carbon storage in the stack, the anode was fabricated outside the tubular cells so that carbon fuel can be loaded at the exterior of the stack, which is more spacious than the interior. The 3-cell-stack is operated directly with carbon as the fuel and oxygen in ambient air as the oxidant. With a total effective area of 10.2 cm² and a 5% (w) Fe-loaded activated carbon fuel of 17 g, the stack reveals a peak power of 4.1 W at 800℃. The stack discharged at a constant current of 1.0 A for 19 h, giving a charge capacity of 19 A·h and an energy capacity of 31.6 W·h, which are much higher than those of a similar stack with anode on the inside and carbon loaded at the interior. The high capacity of our DC-SOFC opens up potential applications in portable devices.     

双中心MOFs衍生的Co-ZnO@CN纳米材料作为电化学催化剂用于氧还原反应的研究

采用水热法合成了一系列的Co-Zn-MOF材料,随后将其在高温下热解,采用自模板的方式得到双中心MOFs衍生的Co-ZnO@CN纳米催化剂.通过调节前驱体的比例和热解温度,优化了制备Co-ZnO@CN纳米催化剂的条件.利用粉末X射线衍射(XRD)和X射线光电子能谱(XPS)对Co-ZnO@CN纳米催化剂的结构及表面化学性质进行表征,采用扫描电子显微镜(SEM)和能量色散谱仪(EDS)考察了Co-ZnO@CN纳米催化剂的形貌和表面化学元素的种类和组成.通过氧还原反应(ORR)测试了催化剂的催化性能.实验结果表明当热解温度为800℃,Co与Zn摩尔质量之比为1∶2时,所得到的Co-ZnO(1∶2)@CN-800纳米催化剂的催化活性最高,其起始电势和半波电势分别为0.90和0.78 V,此外,通过计算表明该纳米催化剂在氧还原反应中氧分子还原过程遵循4e-反应路径.     

Using 3D Composite Electrode Materials for Electricity Generation from Swine Wastewater in a Dual‐Chamber Microbial Fuel Cells

Swine wastewater has a high concentration of organic matter, suspended solids, and higher ammonia nitrogen, odor, complex polluting ingredients, and large emissions. A two‐chambered cubic microbial fuel cell (MFC) was used to evaluate the effect of a novel three‐dimensional (3D ) electrode made of 3D iron composites and 3D stainless composites on the electricity generation. Swine wastewater with a total chemical oxygen demand (TCOD ) of 3688 ± 300 mg/L was used as the feedstock in the anode chamber. The MFC reactor was incubated with an initial pH of 7.0 in an air shaker with a temperature of ~35°C and 100 rpm in the fed‐batch mode. A fixed external resistance (R ) of 100 Ω was connected between the electrodes, and the closed‐circuit potentials of the MFCs were recorded every 5 min. The results showed that using an iron–carbon fiber composite 3D electrode resulted in a peak electricity generation of 321 mV on the first 2 days and maintained a stable voltage of 163 mV during the second to sixth days. The COD removal efficiency could reach 75%. Using a stainless–carbon fiber 3D electrode could generate a peak voltage of only 29.5 mV and a stable voltage of 15.2 mV with a COD removal efficiency of 54%.     

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

Sustainably produced biofuels, especially when they are derived from lignocellulosic biomass, are being discussed intensively for future ground transportation. Traditionally, research activities focus on the synthesis process, while leaving their combustion properties to be evaluated by a different community. This Review adopts an integrative view of engine combustion and fuel synthesis, focusing on chemical aspects as the common denominator. It will be demonstrated that a fundamental understanding of the combustion process can be instrumental to derive design criteria for the molecular structure of fuel candidates, which can then be targets for the analysis of synthetic pathways and the development of catalytic production routes. With such an integrative approach to fuel design, it will be possible to improve systematically the entire system, spanning biomass feedstock, conversion process, fuel, engine, and pollutants with a view to improve the carbon footprint, increase efficiency, and reduce emissions.