氮掺杂碳纳米管的制备及其应用

氮掺杂可以调控碳纳米管的电子结构及表面性质,以吡啶氮、吡咯氮(N-5)、石墨氮、氧化吡啶、-NO2及-NH2等形式进行掺杂的含氮官能团可提高碳纳米管的氧还原催化活性、赝电容、润湿性能及供电子特性。文章综述氮掺杂碳纳米管的3种制备方法:同步原位掺杂、碳化含氮物质、后处理,及其在氧还原反应、超级电容器和支撑材料方面的应用,并综述了不同种类含氮官能团的作用。     

卤化银彩色照相材料

其中R_1为有置换基的烷基、烯基、芳基及多环基,R_2为氰基或带有置换基的N-苯胺基甲酰基,У为-CO-、-SO_2-氮原子、氧原子及硫原子,双键结合时为没有氢的碳原子,z为含氮的4～6个多元环核所必须的非金属原子群。     

大同煤循环流化床的O_2-CO_2预热特性

利用循环流化床高温预热技术,对大同煤在O_2-CO_2环境下预热前后的颗粒特性、燃料特性和燃料氮的转化特性开展研究。结果表明,循环流化床可将大同煤稳定预热至850℃,预热所需的热量全部由煤粉自身的部分燃烧提供。预热后的半焦颗粒粒径减小,比表面积和孔容积分别增大10和2倍,孔隙结构更加发达;大同煤在循环流化床O_2-CO_2预热中,煤气中CO、H_2、CH_4和CO_2体积分数分别为11.5%,9.7%,2.11%和79.6%,煤气热值为2 848.7 kJ·m~(-3);预热过程,煤中的N-Q和N-X向N-6和N-5发生了转化,N-6质量分数由原煤的17.28%增大到32.11%。     

活性炭纤维改性表面官能团脱硫作用

阐述几种表面官能团及其脱硫作用,概括出了4种主要的含氮官能团,即:类吡啶、类吡咯、类酰胺和铵盐,并评价其脱硫作用。通过文献总结出了活性炭材料的高温分解作用和在一定温度下含氧官能团与含氮官能团的分解作用,提出了改性含氮官能团的"两步走"方法:(1)在900℃高温热处理活性炭材料;(2)负载含氮物质,并在650℃左右进行活化改性,此种改性方法负载的含氮官能团数量相对更多。     

常压介质阻挡放电对聚苯乙烯表面改性研究

鉴于介质阻挡放电(DBD)是工业上非常有前途的处理材料表面的环保技术,于是采用常压DBD产生的空气低温等离子体对聚苯乙烯(PS)薄膜进行了表面改性.通过接触角测量、原子力显微镜(AFM)观察和X射线光电子能谱(XPS)分析,研究了空气等离子体处理前后PS薄膜的表面性能的变化.结果表明,PS膜表面润湿性随处理时间的延长而提高,PS膜表面粗糙度增加,而且在表面10nm范围内引入了含氧和含氮的官能团.等离子体处理后PS薄膜润湿性改善的主要原因是由表面粗糙化和引入含氧、含氮极性官能团的复合作用造成的.     

富氮多孔纳米炭纤维的制备及其用作超级电容器电极材料

以商业聚酰亚胺树脂为前驱体,经过静电纺丝和一步炭化制备出富含氮原子的纳米炭纤维,采用扫描电镜、低温氮吸附和XPS等手段对纳米炭纤维的结构进行表征,考察不同炭化温度下纳米炭纤维的孔结构与表面含氮官能团的演变。结果显示,所得聚酰亚胺纤维经过一步高温处理便可得到微孔发达且富含氮原子的纳米炭纤维。随着炭化温度的升高,纳米炭纤维的比表面积与氮含量均逐渐降低。700℃炭化得到的纳米炭纤维的比表面积达到447 m2/g、纤维平均直径为234 nm、表面氮含量达到4.1%。将所得纳米炭纤维直接用作超级电容器电极,采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行考察。所得富氮纳米炭纤维表现出优异的电容量和表面电化学活性,其比电容达到214 F/g,单位比表面的电容量达到0.57 F/m2。     

高强高模碳纤维表面电化学氮化机制

高温石墨化使高强高模碳纤维(CF)表面光滑,反应活性低,导致其复合材料界面粘接性能差。杂原子改性是改善CF表面反应活性的有效手段之一。采用循环伏安(CV)方法在有机复合电解液中对高强高模CF进行了表面氧化和氮化改性,采用CV优选的复合电解液进行恒流电化学氧化处理,研究了CV扫描次数和电解液中含氮有机物对CF表面化学组成的影响。电化学处理前后CF表面化学元素组成和微观形态变化通过XPS、SEM及拉曼光谱表征。基于实验数据探讨了CF表面含氮官能团的生成及转变机制。研究结果显示,有机溶剂、有机氮源和含硫铵盐的协同作用使CF表面N含量从0.28at%增至4.77at%。适量的水存在,可以使CF表面O含量显著提高。CF表面的含氧官能团可以与CO(NH₂)₂中的-NH₂及电解液中的NH₄⁺反应形成酰胺基团,随着反应时间延长,CF表面的酰胺N会先转变成氧化氮,随后转变成吡啶和吡咯N,并最终转换成石墨N。恒流电化学处理后CF/环氧树脂复合材料的层间剪切强度(ILSS)较未处理的提高了132%,...     

超大比表面积ACF和常规ACF表面结构比较

聚丙烯腈基超大比表面积ＡＣＦ（ＨＳＡＣＦ）与常规的小比表面积ＡＣＦ具有不同的表面结构,常规ＡＣＦ具有较为完善的微晶结构,含有比较丰富的杂原子官能结构,主要存在于骨架碳上的含氮官能团含量较大;而对于ＨＳＡＣＦ,超微粒子尺度减小（类石墨微晶基本不存在）,主要存在于骨架碳上的含氮官能团含量较小,杂原子官能结构的浓度和化学状态与常规ＡＣＦ大不相同,这些都使ＨＳＡＣＦ具有与常规ＡＣＦ不同的纳米孔空间表面结构     

氮掺杂活性炭及其载铂催化剂氧还原催化活性

采用化学原位聚合法制备聚吡咯/活性炭(AC)复合物,在惰性气氛进行热处理,制备了氮掺杂活性炭(NAC)。利用化学浸渍还原法制备AC和NAC载铂催化剂,并对比分析他们的氧还原催化性能。氮掺杂处理明显降低了活性炭的比表面积,但因其改善了活性炭水分散性和表面活性,铂在NAC表面沉积和分布较在AC载体表面更均匀。尤其经900℃炭化处理获得的氮掺杂活性炭NAC900,源于其微孔的高比表面积和含氮官能团共同作用,使铂粒子多以尺寸小于5 nm的粒子均匀沉积分布于载体表面,且铂担载量高。循环伏安曲线分析表明,与活性炭载铂催化剂(Pt-AC)相比,氮掺杂活性炭载铂催化剂(Pt-NAC900)的氧还原峰电位更正,氧还原峰电流为前者两倍,且峰电流随循环次数的衰减更低。结果表明,通过对传统炭材料活性炭进行氮掺杂处理,能够增强其载铂催化剂氧还原催化性能。     

氮掺杂水热碳/石墨烯复合膜的制备及其性能研究

以废弃柚子皮瓤和氧化石墨烯(GO)为碳源，氨水为掺杂剂，采用水热与真空抽滤相结合的方法，制备氮掺杂石墨烯(N-G)、氮掺杂水热碳膜(N-HC)和氮掺杂水热碳/石墨烯复合膜[N-HC/G-X,X=1、2、4、5,X代表柚子皮瓤(g)与GO(mg)的质量比],利用扫描电镜、X射线衍射、拉曼光谱和红外光谱表征碳材料的物理化学性质，并进行了吸附Zn(Ⅱ)和截留Cr(Ⅵ)的实验。结果表明：N-G、N-HC和N-HC/G-X均为典型片层结构，N-HC是获得薄膜的必要成分，N-HC/G-1和N-HC/G-2的成膜效果优于N-HC/G-4和N-HC/G-5,N-HC/G-1的膜厚度大约为65μm, C、N和O的质量分数分别为65.63%、15.06%和19.31%。N-G、N-HC和N-HC/G-X都是无定形碳材料，N-HC的d₀₀₂片层间距最大，随着N-HC/G-X中N-G质量的逐渐增多，N-HC/G-X的片层间距逐渐减小，表面缺陷和混乱程度有所增大，且N-HC/G-X表面存在大量的含氧和含氮官能团，可以提供更多活性吸附位点，有利于提升对重金属的吸附效果。N-HC/G-1和N-...     

Structure-dependent response of a chemiluminescence nitrogen detector for organic compounds with adjacent nitrogen atoms connected by a single bond

High-throughput screening (HTS) of chemical libraries is indispensable for drug discovery research. However, the HTS data quality for lead discovery, lead optimization, and quantitative structure activity relationship studies has been severely compromised due to the uncertain compound concentrations in screening plates. In order to address this issue, we compared various high-throughput technologies for quantification of compounds in microtiter plate format without the need for authentic compounds as standards and identified the chemiluminescence nitrogen detector (CLND) as the method of choice at the present time. However, the structure dependence of this detector has not been well studied. A proposed rule suggested that the only exception to equimolar response is for compounds that contain adjacent nitrogen atoms. The response should be zero when the adjacent nitrogen atoms are connected by a double bond and 0.5 when they are connected by a single bond. In this investigation, we studied a broad range of compounds with isolated and adjacent nitrogen atoms. We confirmed that compounds with isolated nitrogen atoms produce an equimolar response with a 15-20% variation depending on structures and compounds with adjacent nitrogen atoms connected by a double bond giving nearly zero response. We discovered that the CLND response for compounds containing adjacent nitrogen atoms that are connected with a single bond is highly structure dependent. Substitutions on the nitrogen atoms or nearby in the molecule can increase the CLND response to approach a value higher than the predicted value 0.5 (maximal value 0.82/nitrogen atom). Without substitution, much lower values than predicted (minimal value 0.0-0.08/nitrogen atom) are obtained. Therefore, the prediction of response of 0.5/nitrogen atom for compounds with adjacent nitrogen atoms connected by a single bond should be abandoned. Compounds with similar structures should be used to generate calibration curves for quantification of this class of compounds.     

Enhanced electrochemical performances of heteroatom-enriched carbon with hierarchical pores prepared by trehalose as a pore-forming agent and a simple one-step carbonization/activation process for supercapacitors

It is highly desired to simultaneously introduce active heteroatoms and abundant hierarchical pore structures for enhanced electrochemical performances on carbon materials. Herein, trehalose as a pore-forming agent was added into polyvinylpyrrolidone/melamine formaldedyde resin mixture with high concentrations of nitrogen and oxygen. Then a simple one-step carbonization/activation process was adopted and heteroatom-enriched carbon with hierarchical pores (HPC) was fabricated successfully. HPC/HPC symmetric supercapacitors were assembled using KOH electrolyte. It is clearly demonstrated that due to the pore-forming action of trehalose HPC shows the porous honeycomb, interconnected and worm-like pore structure, which is favorable to enhance the double-layer capacitance. It is confirmed that in our system the three active species of pyridinic nitrogen (N-6), pyrrolic nitrogen (N-5) and quinone type oxygen (O-I) are responsible for the pseudocapacitive behavior. Based on XPS, nitrogen adsorption/desorption isotherms and electrochemical impedance spectroscopy, it is deduced that the ratio-optimized HPC-T30 exhibits high concentration of three active species (8.17 at.%), increased specific area (351.26 m² g^?1) and tuned hierarchical pore structures with substantial micropores (micropore area of 321.68 m² g^?1) and a small amount of mesopores and macropores, which lead to decrease of charge transfer resistance, increase of transfer rate of electrolyte ions in the pores and excellent electrochemical performances. In cyclic voltammetry tests of three-electrode system and galvanostatic charge/discharge tests of two-electrode system, HPC-T30 displays high specific capacitance, 46% and 1.2-time enhancement compared to untreated HPC-T0, respectively. The optimized HPC-T30/HPC-T30 supercapacitor delivers the energy density of 6.69 W h kg^?1 in 6 M KOH electrolyte. Furthermore, the supercapacitor shows a capacitance retention of 91.16% up to 6000 cycles and the coulombic efficiency reaches nearly 100% for each charged/discharge cycle, demonstrating its good cyclic stability.     

Crystal structure and optical properties of oxynitride rare-earth tantalates RTa-(O, N) (R = Nd, Gd, Y)

X-ray absorption and photoluminescence were used to investigate the structure of rare-earth tantalum oxynitrides RTa-(O, N) (R = Nd, Gd, Y). Owing to the size of the rare-earth element, the crystal structure tends towards the pyrochlore or defect fluorite-type structure. EXAFS suggested neodymium and yttrium atoms are coordinated either by 6 + 2 or 6 oxygen/nitrogen atoms in the Nd or Y respective oxynitrides although the coordination number of tantalum is six in both compounds. Photoluminescence for 5 at.% doped europium showed the spectra compatible with the point symmetry C_3v lower than O_h in fluorite and D_3d in pyrochlore structure type for both the Gd and Y tantalum oxynitrides. These measurements supported that their structure types were basically pyrochlore for Nd and Gd tantalum oxynitrides and defect fluorite for Y tantalum oxynitride but they are highly defective.     

Thermal reactivity of some nitro- and nitroso-compounds derived from 1,3,5,7-tetraazabicyclo[3.3.1]nonane at contamination by ammonium nitrate

Thermal reactivity of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DPT), 3,7-dinitroso-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DNPT), 1,3,5-trinitroso-1,3,5-triazinane (TMTA or R-salt), 1,3,5-trinitro-1,3,5-triazinane (hexogen or RDX), 1,5-diacetyl-3,7-dinitro-1,3,5,7-tetrazocane (DADN), alpha-modification of the 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (octogen or HMX) and of their mixtures with 2wt.% of ammonium nitrate (AN) has been examined by means of non-isothermal differential thermal analysis. The resulting data were analyzed according to the Kissinger method. The reactivity was expressed as the E(a)R(-1) slopes of the Kissinger relationship. A relatively high reactivity has been found with mixtures of DPT and DNPT with AN. Electronic charges q(N) at nitrogen atoms in molecules of the compounds studied were calculated by means of ab initio DFT B3LYP/6-31G** method. The relationships were confirmed between the slopes E(a)R(-1) and the q(N) values for the nitrogen atoms primarily undergoing reaction. On the basis of these relationships it is stated that the destabilizing effect of AN is due to acidolytic attack of nitric acid (resulting from dissociation of ammonium nitrate) at the nitrogen atoms with the most negative q(N) values in the molecules of the compounds studied.     

Synthesis and characterization of titanium and zirconium oxynitride coatings

Thin films of zirconium oxynitride (ZrNO) and titanium oxynitride (TiNO) have been deposited onto Si(100) substrates at room temperature by radiofrequency magnetron sputtering in an argon-oxygen-nitrogen atmosphere. Single oxynitride layers have been stacked to obtain a multilayer structure. The film structure has been determined by X-ray diffraction while compositional analysis has been performed by X-photoelectrons spectroscopy. Structural analysis has shown that TiNO can be represented as a cubic structure where oxygen atoms replace nitrogen ones while ZrNO can be described as a cubic ZrO₂ where nitrogen atoms replace oxygen ones. Besides the main peak, the multilayer films show satellite peaks, proving the formation of the stacked structure. The final films stoichiometry has been explained by a growth model. It establishes that in TiNO films the nitrogen vacancies filling by reactive reactions with oxygen atoms is favourite while for ZrNO films the oxygen vacancies filling by energetic nitrogen atoms is more likely to happen. The different behaviour between TiNO and ZrNO is further confirmed during the multilayer growth.     

Higher visible photocatalytic activities of nitrogen doped In2TiO5 sensitized by carbon nitride

N-doped In(2)TiO(5) modified by carbon nitride (CN) composite (NICN) has been prepared by the pyrogenation of the mixture of urea and In(2)TiO(5) through a polymerizable complex (PC) method. The powder samples were characterized by XRD, FESEM, TEM, UV-vis, and XPS. It is shown by XRD that the precursor sintered at 1000°C is pure and nitrogen dopant does not change the crystal structure of In(2)TiO(5). FESEM and TEM reveal a hole-like morphology of the prepared NICN. With the increase of nitrogen content, the light absorption onset of In(2)TiO(5) shifts from 410 nm to 450 nm, revealing significant narrowing of the band gap. XPS results suggest that only 2.2% of the nitrogen atoms were doped into In(2)TiO(5) through the urea pyrogenation method. Furthermore, the decomposition of Rhodamine B (Rh-B) under visible light reveals that Rh-B can be degraded completely within 20 min and recycling experiments indicate NICN has stable structure and durable photocatalytic activity, suggesting a promising utilization of such photocatalyst under visible light. Finally, an innovative mechanism of N-doped In(2)TiO(5) sensitized by carbon nitride polymer is proposed.     

Beneficial effects of nitrogen on austenite antibacterial stainless steels

Nitrogen is a significant alloying element in austenite stainless steels. The aim of this paper is to evaluate the effects of nitrogen on the microstructure and properties of austenite antibacterial stainless steels. Two austenite antibacterial stainless steels containing copper and different nitrogen concentration (0.02 and 0.08 wt%, respectively) were fabricated. The microstructures and composition analysis were carried out using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Auger electron spectroscopy (AES). The epsilon copper-rich precipitates are spherical and less than 20 nm in size, with a cube-on-cube orientation relationship with the matrix. They are dispersed on the steel surface with a mean space of about 200 nm. Nitrogen cannot only improve the antibacterial property but enhance significantly the corrosion resistance in chloride media. Nitrogen compensates the harmful effect of epsilon copper precipitates on the corrosion resistance. The nitrogen concentration in the surface of N-2 steel is four times as much as in the surface of N-1 steel. Nitrogen enrichment in the steel surface improves the corrosion resistance. The presence of higher nitrogen increases the strength and decreases the ductility of austenite antibacterial stainless steel, which could be related to the variation of stacking-fault energy associated with nitrogen concentration.     

氮分压对ZrN薄膜结构及颜色的影响

采用直流反应磁控溅射法,通过改变反应气体N2分压(5%、10%、20%、30%、40%、50%、60%),在SiO2/Si(111)基片上制备ZrN薄膜。利用XRD、SEM、EDS分析了薄膜的物相、结构、形貌以及成分,使用分光光度计测量了薄膜的反射光谱,并进一步确定了薄膜颜色在L*a*b*色度坐标中的位置,研究了氮分压对薄膜颜色的影响,以及ZrN薄膜颜色与薄膜成分、结构之间的关系。分析结果表明:在不同的氮分压下,ZrN薄膜具有较好的成膜质量;随着氮分压的增加,薄膜沉积速率降低、N含量增加;薄膜结晶度先升高后降低、且在氮分压为10%时,薄膜出现(111)的择优取向;薄膜颜色随薄膜成分结构的改变而发生明显的变化(颜色由银色向金色、暗金、深褐色以及非本征颜色转变)。当反应气体N2分压较低时,分压的增加使得锆与氮更容易键合,导致薄膜中N含量增加,使ZrN结晶度增大并出现择优取向。当N2分压超过10%后,薄膜中多余的氮处于晶格的间隙位置,使得薄膜晶格间距变大且结晶度降低,薄膜成分结构的改变导致了薄膜颜色的变化。     

非季铵盐型松香基表面活性剂的研究进展

综述了非季铵盐型松香基表面活性剂的研究进展,系统归纳了其合成概况和基础物理性质。合成进展中以对松香改性增强亲水性能的亲水基团成键机理为主线,对表面活性剂进行分类总结,包括仅含氧(O)原子基团的醚、酯、羧酸类表面活性剂,含氧(O)和氮(N)原子基团的氨基酸类表面活性剂,含氧(O)和硫(S)原子基团的硫酸、磺酸类表面活性剂以及含氧(O)、氮(N)和硫(S)原子基团的胺基盐类表面活性剂。通过归纳非季铵盐型松香基表面活性剂的物理性质数据,剖析其与普通柔性长链表面活性剂物理性质区别,并对其研究和应用现状进行了展望,指出该类表面活性剂在胶束化行为研究和功能材料合成中具有重要发展潜力。     

氮掺杂碗状空心碳微球的制备及其 在超级电容器中的应用

针对碳电极材料存在比电容小、能量密度低的问题,采用异质成核合成路径制备了新型的碗状空心碳微球,进一步以尿素为氮源,通过水热法制备了高性能氮掺杂碗状空心碳微球。采用X射线衍射仪、场发射扫描电子显微镜、能谱仪、傅立叶红外光谱仪和X射线光电子能谱分析仪对碗状空心碳微球和氮掺杂碗状空心碳微球的形貌及结构进行表征,并分析了氮掺杂对碗状空心碳微球的电化学性能。实验结果表明:氮掺杂对碗状空心碳微球的电化学性能有显著的改善,在1 A/g的电流密度下,氮掺杂碗状空心碳微球的比电容(235.5 F/g)远高于碗状空心碳微球的比电容(121.0 F/g),此外,氮掺杂碗状空心碳微球在3 A/g的电流密度下循环5 000次后,其比电容保持率为78.3%。