Electrodeposition of Pd–Ag alloy nanowires on highly oriented pyrolytic graphite

This paper reports findings of an investigation of Pd–Ag alloy nanowires on the step edges of highly oriented pyrolytic graphite (HOPG) by electrochemical deposition at room temperature. Scanning electron microscopy (SEM) images reveal that these alloy nanowires (109–430 nm) are uniform in diameter, and have lengths up to 100–500 μm. The electrodeposition process involves the initial formation of nanowires induced at the step edges of the oxidized HOPG substrate at a very negative potential and subsequent growth at a constant low current density to coalesce the discontinuous nanowires. Alloy nanowires with a 20–25% silver content can be obtained when the ratio of Pd and Ag in the solution is carefully controlled. The SEM images demonstrate that the alloy nanowire arrays are continuous, parallel, ordered, well-aligned and have a narrow distribution of diameters. The Pd–Ag alloy nanowire arrays are promising materials for fabricating hydrogen nanosensors.     

定量校准曲线法测定超高纯试剂丙酮中铁含量的研究

目前最常用的分析曲线法(标准曲线法、校准曲线法)、内标法、标准加入法等,对丙酮这类基体成分丰富的样品测定,其定量校准存在显著的系统误差.实验证实,通过保证标准系列中基体组成、浓度及酸度与待测样基本相同,来制作工作曲线进行定量校准(下称定量校准曲线法),能得到较为理想的结果.     

石墨材料的疲劳

对迄今前人在石墨材料上所开展的疲劳研究工作进行了综述，以不同的疲劳设计方法为线索，一方面通过对石墨寿命评价的S-N曲线来分析石墨的疲劳行为；另一方面从疲劳裂纹扩展的角度来分析在外应力作用下有预制裂纹的石墨的疲劳行为。总结了石墨疲劳研究的主要进展，归纳了石墨疲劳研究中的关键问题，在此基础上对石墨材料的疲劳研究前景进行了展望。     

Alkaline peroxide generation using a novel perforated bipole trickle-bed electrochemical reactor

A novel perforated bipole trickle-bed electrochemical reactor is investigated for the electro-synthesis of alkaline peroxide. The process uses a relatively simple cell configuration in which a single electrolyte flows with oxygen gas in a flow-by graphite felt cathode, sandwiched between a micro-porous diaphragm and a perforated bipolar electrode plate. The graphite felt cathodes are 120 mm high by 25 mm wide and have a thickness of 3.2 mm. The reactor is operated at current densities in the range 1–5 kA m⁻², ca. 800 kPa (abs) pressure and temperature (In/Out) 20–45 °C with one and two-cells. The reactor shows good performance (current efficiency ∼78% at 2 kA m⁻² and a specific energy of 5 kWh per kg of peroxide generated) with peroxide concentrations from 0.02 to 0.15 M in 1 M NaOH.     

Gas flow through highly porous graphite matrices

Highly porous graphite matrices with 20-200 kg m⁻³ of bulk densities have been characterized using helium pycnometer, mercury porosimeter, and fluid flow methods, i.e. both gas permeation and diffusion measurements. The gas permeability is ranging from 10⁻¹² to 10⁻¹⁵ m² and decreases as the bulk density of the graphite matrix increases. According to the Carman-Kozeny correlation, the evolution of the gas permeability with respect to the bulk density is very well correlate with, on the one hand, the increase of the tortuosity, and on the other hand, the decrease of the porosity as well as the pore diameter with the bulk density of the graphite matrix.     

钽平台-石墨炉原子吸收法测定高背景废水样品中的Cd、Pb

运用钽平台石墨管测定基体成分复杂的废水样品中的Cd、Pb元素,基本消除了基体残留影响和记忆效应,降低了背景吸收,提高了灵敏度。样品经超声波仪粉碎后直接进样,用校正曲线法测定,简化了操作步骤,减少了测定时间,延长了石墨管使用寿命。其测定值与石墨平台标准加入法测定值结果一致。样品回收率:Cd为96.9%～104%,Pb为98.2%～106%,Cd的相对标准偏差(RSD)为3.04%～4.24%,Pb的RSD为2.93%～6.53%。     

Electrical resistivity and magnetoresistance of carbon/graphite fibers intercalated with nitric acid and arsenic pentafluoride

A series of high performance, experimental carbon/graphite fibers was intercalated and examined with respect to their metallic conductivity behavior by resistivity and magnetoresistance versus temperature measurements. One fiber was a polyacrylonitrile (PAN)-type precursor and three were pitch base precursors. All four types showed substantially similar behavior in the pristine state with respect to room temperature resistivity and the sign and magnitude of the temperature coefficient of resistivity. After intercalation with either nitric acid or nitric acid followed by AsF₅, the PAN-based fibers displayed a resistivity versus temperature behavior qualitatively similar to their pristine counterparts but displaced to lower resistivity. On the other hand, the pitch fibers with the same intercalation treatment exhibited metallic behavior (a positive temperature coefficient of electrical resistivity and a small magnetoresistance). These manifestations of metallic behavior are usually indicative of some three dimensional graphite structure in the carbon fibers.     

商业化的锂离子电池石墨负极材料的研究进展

综述了锂离子电池石墨负极材料的研究进展,对MCMB、天然石墨与人造石墨、炭纤维为代表的石墨负极材料目前的研究和应用现状进行了详细的论述,并对石墨类炭负极的发展作了展望。     

膨胀石墨的研究

阐述了膨胀容积和硫的质量含量是决定膨胀石墨质量的两个重要指标，探讨了石墨与高锰酸钾、三氯化铁的质量与膨胀容积的关系。