氮直流辉光放电活性粒子(N~+,N)的产生率

在氮直流辉光放电等离子体中采用快电子和离子(N+2,N+)混合的蒙特卡罗模型,模拟研究了e+N2→N+ N+N+2e e和N+2+N2→N++N+N2过程中粒子(N+,N)产生率的轴向分布随放电参数(工作气压、放电电压和温度)的变化规律。结果表明:两种离解过程中氮活性粒子(N+,N)的产生率都随气压和电压的增加而增大,随放电气体温度的升高而降低;但N+2-N2离解碰撞主要发生在阴极附近。电压较高时,阴极处的离子N+主要由N+2-N2离解过程产生;电压较低时,N+2-N2离解过程可忽略。中性原子N主要由电子碰撞离解过程产生。     

Reactivity and transformation routes of surface nitrates in the reaction of NOx reduction by C3H8 over cation-exchanged zeolites

FITRS combined with¹⁵N and¹⁸O isotope substitution and TPD have revealed that nitrates are the most abundant ad-NO_x species on over-exchanged Cu- and Co-ZSM-5 zeolites. the transformation rates of such species under the action of a propane—oxygen mixture were found to be comparable and sufficiently high to afford steady-state catalytic activities. A scheme of the reaction mechanism including C, N-containing intermediates detected in work is suggested.     

Transformations of 2,2-dimethyl-2,4-dihydro-3H-pyrrol-3-on-1-oxide derivatives in the Vilsmeier-Haack reaction conditions

Enhydroxylaminones—2,2-dimethyl-2,4-dihydro-3H-pyrrol-3-on-1-oxides were shown to give various chlorinated products in the Vilsmeier-Haack reaction. The general sequence of the reaction steps is determined and the extent of the reaction was shown to be strongly dependent on the substrate structure.     

HL-2M 装置真空烘烤控制系统概述

HL-2M 真空烘烤系统采用两台可编程逻辑控制器(PLC)构成一个自动控制系统,根据工艺要求编制 相应逻辑程序来控制各执行机构,实现对系统加热器电功率、换热器热负荷以及阀门开度的程序调节,达到±2℃ 温升梯度的烘烤目的。PLC 与阀岛建立工业以太网(Profinet)通信协议,通过地址映射的方式控制进出真空室和偏 滤器的开关阀,调整烘烤系统的负载投入。     

氮气流量对磁控溅射InN薄膜特性的影响

采用射频磁控溅射法在蓝宝石衬底上制备了InN薄膜. 研究了N2流量对InN薄膜的晶体结构、表面形貌、光学和电学特性的影响. X射线衍射(XRD)测试结果显示,InN呈六方纤锌矿结构,具有明显(002)择优取向;SEM与AFM图像显示InN薄膜均匀致密,低N2流量下随流量增加,表面逐渐趋于光滑平整,过高的N2流量使薄膜生长方式发生改变;通过检测薄膜吸收特性,利用线性外推法计算禁带宽度为1.81~1.96 eV;电学测试结果表明,制备的薄膜样品均呈现n型导电特性,且迁移率较低,最大为12.2 cm2/v∙s;载流子浓度较高,保持在1021 cm-3数量级;电阻率较小,范围是0.202~0.33 mΩ∙cm.     

Effect of thermal annealing on nitrogen implanted epitaxial Fe films

Nitridated iron is a promising material for potential applications in permanent magnets. Recent work on stabilization of nitridated iron in a foil form through nitrogen ion implantation and annealing motivates to study effect of thermal annealing on the surface of nitrogen-implanted iron. In this work, we show effect of annealing on chemical state and magnetism of nitrogen implanted epitaxial iron films. It is observed that nitrogen in the lattices only stays at the lower temperatures than 450 °C. In addition, significant reduction and lattice modification are taken placed, when the film is annealed at 450 °C. The increases of saturation magnetization and coercivity, where it is annealed at 450 °C, are likely to be triggered by reduction of oxygen contents at the surface and thinning of Fe₂O₃.     

聚苯胺改性氮掺杂碳纳米管制备及其超级电容器性能

利用苯胺原位化学聚合合成聚苯胺包覆碳纳米管(CNTs), 再炭化处理制备氮掺杂碳纳米管(NCNTs).激光拉曼(Raman)光谱和X射线光电子谱(XPS)分析及透射电镜(TEM)观察表明, 苯胺包覆碳纳米管经炭化处理后, 得到以碳纳米管为核、氮掺杂碳层为壳, 具有核-壳结构的氮掺杂碳纳米管, 而碳纳米管本征结构未遭破坏. 研究表明, 随着苯胺用量的增大, 氮掺杂碳纳米管的氮掺杂碳层变厚, 氮含量从7.06%(质量分数)增加到8.64%, 而作为超级电容器电极材料, 随着氮掺杂碳层厚度降低, 氮掺杂碳纳米管在6 mol·L^-1氢氧化钾电解液中的比容量从107 F·g^-1增大到205 F·g^-1, 远高于原始碳纳米管10 F·g^-1的比容量, 且聚苯胺改性氮掺杂碳纳米管表现出较好的充放电循环性, 经1000次充放电循环后仍保持初始容量的92.8%~97.1%, 表明氮掺杂碳纳米管不仅通过表面氮杂原子引入大的法拉第电容和改善亲水性使电容量显著增大, 其具有的核壳结构特征也使循环稳定性增强。     

Conformation of Poly-(L-lysine) Containing Some Azoaromatic Side Chains

The pH dependence of the conformation of poly-(L-lysine) with 4.6 mol% of its side chain amino groups attached to an azo dye, 4′ -dimethyl aminoazobenzene-4-carboxylic acid, has been studied. Circular dichroic spectra showed that in acidic as well as in neutral media the polymer exists in the random coil conformation, like that of poly-(L-lysine). In basic medium the polypeptide acquires a β-structure, unlike poly-(L-lysine) which exists in an α-helical conformation.     

氮掺杂碳纳米管的合成及活化过一硫酸盐的性能与机理

以多壁碳纳米管(MWCNT)为原材料, 三聚氰胺为氮前体, 采用高温煅烧法制得了含氮量约3.33%(摩尔分数)的氮掺杂碳纳米管(N-CNT-700), 该纳米管为一维材料. N-CNT-700活化过一硫酸盐(PMS)体系60 min内对苯酚的降解效率可达100%, 总有机碳(TOC)去除率可达61.6%, 体系的活化能为35.4 kJ/mol. 通过电子顺磁共振(EPR)检测、 掩蔽实验及PMS浓度测定等方式确定了体系降解机制为自由基(·OH, SO₄^·-)与非自由基共同作用, 除去9%的吸附去除外, 91%的氧化降解中自由基作用占比约49%, 单线态氧(¹O₂)作用占比约18%, 活性中间体作用占比约24%. N-CNT-700的反应活性随着重复利用次数的增加而降低, 高温处理可以恢复其高反应活性. 煅烧温度影响材料中的氮含量及种类, N-CNT的反应活性与氮含量成正比, 且与石墨氮含量密切相关.     

氨氛围热处理g-C_3N_4控制N空位浓度提高光催化制氢性能

热处理氧化石墨相氮化碳(g-C_3N_4)材料产生氮缺陷、提升其光催化制氢性能的研究备受关注,但其N空位浓度高且不可控、一定程度破坏g-C_3N_4晶体结构,降低g-C_3N_4的结晶度,导致光生电子-空穴对复合率高,致使其光催化制氢效率较低。基于上述问题,本研究以二氰二胺为前驱体制备了g-C_3N_4,与不同含量的尿素混合,在空气中加热快速热处理,通过X-射线衍射仪(XRD)、扫描电子显微镜(SEM)等测试手段,对其物相组成、微观形貌、光学吸收等进行了表征,在可见光条件下对样品进行了光催化制氢性能测试,研究了尿素的加入对热处理后g-C_3N_4材料的N空位浓度、结晶度及光催化制氢性能的影响。研究表明,尿素的加入降低了N空位的浓度,且提升了其结晶度。在优化的尿素添加量下,g-C_3N_4的可见光光催化制氢速率为6.5μmol·h-1,是没有添加尿素处理的样品的3倍。该研究结果表明,利用尿素原位分解产生的NH_3,可以抑制g-C_3N_4热处理过程中氮原子的氧化程度、实现调控N空位浓度,同时提高了结晶度,最终提升了其光催化制氢性能。