Field emission from awl-shaped diamond-like carbon by using filtered cathodic arc plasma technique on anodic aluminum oxide template

Awl-shaped diamond-like carbon (DLC) was directly grown on anodic aluminum oxide (AAO) template by using filtered cathodic arc plasma (FCAP) technique at room temperature. The awls of DLC were about 250 nm in the height and the diameters of the awls were ∼100 nm at the top. The awl density was estimated to be ∼10⁸ cm⁻². A broad asymmetric band ranging from 1100 to 1800 cm⁻¹ was detected by Raman spectrum. This asymmetric band was characteristic band of DLC. The sp³/(sp³+sp²) ratio of C-C bond of the awl-shaped DLC was measured by X-ray photoelectron spectrum, and it was about 68.3%. Field-emission properties of the awl-shaped DLC were investigated. A low turn-on field of 2.6 V/μm at 10 μA/cm² with an emission area of 3.14 mm² was achieved, and the emission current stability was very good. The results indicated that the electrons were emitted under both the effect of enhanced field because of the geometry and the work function of the DLC sample. Based on Fowler-Nordheim plot, the values of work function for the awl-shaped DLC were estimated in ranges of 0.23-1.08 from a linearity plot.     

燃料电池反应器在化学品与电能共生中应用

燃料电池作为能源转换装置能够高效地将化学能转化为电能,随着技术的发展人们将其作为反应器来完成高附加值的化学品的合成,同时产生一定的电能. 燃料电池反应器因具有反应条件温和、反应过程可控、产物选择性高、能源利用效率高等特点,而被广泛地应用于医药中间体的制备、气体分离、水处理等多个领域. 本文首先按照反应器中阴阳极区域发生反应的类型进行分类,介绍燃料电池反应器在化学品与电能联产中的研究现状和研究进展. 随后描述了燃料电池反应器中存在的问题,并依照催化剂、反应过程等方向对解决方案进行探讨. 最后,对几种新型燃料电池反应器的研究进行了简要的介绍并对其发展做出了展望.     

Stripping voltammetry for the determination of trace metal speciation and in-situ measurements of trace metal distributions in marine waters

Progress in marine chemistry has been driven by improved sampling and sample handling techniques, and developments in analytical chemistry. Consequently, during the last 20 years our understanding of marine trace metal biogeochemistry has improved a great deal. Stripping voltammetric techniques (anodic stripping voltammetry and adsorptive cathodic stripping voltammetry) have made an important contribution to this understanding. The selectivity and extremely low detection limits have made stripping voltammetry a widely used technique for trace metal speciation and trace metal distribution measurements in seawater. Stripping voltammetry is very suitable for ship-board and in-situ applications because of the portability, low cost and capability for automation of the voltammetric instrumentation. Future developments in stripping voltammetry can be expected in the field of stand-alone submersible voltammetric analysers, capable of continuous trace metal measurements. Future applications of stripping voltammetry can be found in the interactions between trace metal speciation and growth and the functioning of organisms in pristine and metal polluted marine waters.     

阴极溶出半微分伏安法测定尿嘧啶最佳实验条件的选择

本文利用数理统计的最优化方法,对半微分阴极溶出电分析法测定尿嘧啶的最佳实验条件进行了选择。采用正交试验法对底液浓度、pH等七个因素进行了综合考察。所得各项指标均由计算机进行处理,进行直观分析和方差分析,并绘制各因素与试验指标的关系趋势图,取得了令人满意的效果和最优化的实验条件。本方法不仅比常规的实验方法节省大量时间和人力物力,而且起到综合考察各影响因素的目的。     

钴氢氧化物修饰玻碳电极的镀膜/循环伏安法制备及其电化学行为

采用一种新方法镀膜 /循环伏安法成功制备了钴氢氧化物修饰玻碳电极 .考察了影响钴氢氧化物膜电催化活性的因素 ,确定最佳富集时间为 2min ,最佳活性单元浓度为 9 90× 10 -4mol·L-1.讨论了成膜过程及机理 .膜氧化峰电流 (i0pa)与扫描速率 (v <0 60V·s-1)成正比 ,具有表面吸附反应特征 ,表面覆盖量约相当于 0 5个单层的氧化还原活性物质 .制得的钴氢氧化物膜修饰电极具有相当的稳定性 ,并对H2 O2 氧化表现出较高的电催化活性 .线性回归方程为 :Δipa( μA) =-2 10 3 6+2 3 72 0× 10 4CH2 O2 (mol·L-1) (R =0 9990 ,n =18) ,线性范围为 :1 43× 10 -5～ 1 80× 10 -2 mol·L-1,检出限为 :9 5 9× 10 -6mol·L-1( 3S/k) .