首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17篇
  国内免费   1篇
  完全免费   5篇
  化学   23篇
  2020年   2篇
  2019年   3篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2015年   3篇
  2014年   3篇
  2013年   4篇
  2012年   1篇
排序方式: 共有23条查询结果,搜索用时 27 毫秒
1.
采用微波法在氨气气氛下快速加热石墨烯(G)制备了含氮量在4.05 wt%-5.47 wt%的掺氮石墨烯(NG). 将上述的掺氮石墨烯用作碱性电解质条件下的氧还原电催化剂,起始还原电势为0.17 V(vs SHE),接近商用碳载铂催化剂的0.21 V(vs SHE). 采用透射电子显微镜、拉曼光谱和X射线光电子能谱研究了掺氮石墨烯的形貌、结构和掺杂氮原子的键合方式. 结果发现,掺氮石墨烯的氧还原起始电位随着石墨氮原子含量的提高而上升,说明石墨类型的氮含量是影响其氧还原催化活性的关键因素. 实验结果表明,微波法快速制备的掺氮石墨烯在碱性条件下表现出较高的氧还原催化活性,具有作为碱性燃料电池阴极催化剂的潜力.  相似文献
2.
采用两步热解法,用尿素掺杂氧化石墨烯(GO)得到N掺杂的还原氧化石墨烯(N-RGO),通过控制反应温度,制备了具有不同电催化活性的N掺杂的还原氧化石墨烯.透射电子显微镜(TEM)和扫描电子显微镜(SEM)结果显示,制得的氮掺杂石墨烯(nG)表面褶皱和重叠增加.X射线光电子能谱(XPS)证明,氮元素以吡啶N、吡咯N和石墨化的N 3种形式掺杂在石墨烯中,最高摩尔分数为6.6%.通过循环伏安(CV)和旋转圆盘电极(RDE)测试了nG的电化学性能,结果表明,在酸性电解质中对氧还原(ORR)有较高的催化活性,起始电位在0.1 V左右,电催化还原氧气时主要为四电子反应,且相对商用的Pt/C催化剂有更好的电化学稳定性,其中第一步热解温度为200℃制得的nG催化性能最好.  相似文献
3.
This study develops a powerful strategy for fabricating the nitrogen-doped graphene sheets with good crystallinity, high specific surface area, and high percentages of pyridinic/graphitic-nitrogen structures. Due to the specified N-doping structures and high specific surface area of 719 m2 g− 1, our N-doped graphene sheets show an excellent electrocatalytic activity for the oxygen reduction reaction (ORR).  相似文献
4.
采用化学共沉淀法成功合成了磁性氮掺杂石墨烯纳米材料, 对其吸附性能进行了初步探讨.此磁性纳米材料对对氯间二甲苯酚的吸附不局限于均匀的单分子层吸附,吸附动力学符合准二级动力学模型.将其作为磁性固相吸附剂,通过对吸附剂用量、超声萃取时间、水样pH值、上样体积等条件的优化,建立了超声辅助磁性固相萃取-气相色谱/串联质谱同时测定环境水样中的三氯生(TCS)、对氯间二甲苯酚(PCMX)、六氯苯(HCB)和2,2′,4,4′,5,5′-六氯联苯(PCB-153) 4种有机氯污染物的方法. 在优化条件下,将6.0 mg Fe3O4/N-G分散于100 mL水样中,调节水样至pH 5,超声萃取15 s,磁性分离,3 mL乙醇和2 mL二氯甲烷分步洗脱,洗脱液氮吹定容,进行气相色谱-质谱联用分析.4种有机污染物在0.1~10 μg/L范围内与峰面积呈良好的线性关系,相关系数为0.9983~0.9999,检出限(S/N=3)和定量限(S/N=10)分别为0.05~0.6 ng/L和0.4~2.4 ng/L,3个加标浓度水平的回收率为68.3%~103.4%,日内、日间测定的相对标准偏差分别为3.3%~6.9%和3.4%~9.4%(n=6).本方法简单方便,易于操作,适用于环境水样中有机氯污染物的检测.  相似文献
5.
本文通过化学还原法制备纳米Cu2O/氮掺杂石墨烯(NG)复合材料,用于构建一种新型的多巴胺(DA)电化学传感器.采用X射线衍射法和扫描电镜对纳米Cu2O/氮掺杂石墨烯复合材料进行表征.在pH为7.0的磷酸盐缓冲液中,采用循环伏安法和计时电流法分别研究了DA在纳米Cu2O/氮掺杂石墨烯复合修饰电极上的电化学行为.结果表明,该修饰电极对DA表现出显著的电催化活性,且DA在修饰电极上的反应受吸附控制.在最佳实验条件下,催化电流与DA的浓度在0.5~700 μ mol/L之间呈线性关系(r=0.9943),检测限达0.17 μ mol/L.该修饰电极的选择性高、重复性和再现性好.方法用于实际样品中DA的检测,获得结果较好.  相似文献
6.
In this work, a new solid-phase microextraction fiber was prepared based on nitrogen-doped graphene (N-doped G). Moreover, a new strategy was proposed to solve problems dealt in direct coating of N-doped G. For this purpose, first, Graphene oxide (GO) was coated on Pt wire by electrophoretic deposition method. Then, chemical reduction of coated GO to N-doped G was accomplished by hydrazine and NH3. The prepared fiber showed good mechanical and thermal stabilities. The obtained fiber was used in two different modes (conventional headspace solid-phase microextraction and cold-fiber headspace solid-phase microextraction (CF-HS-SPME)). Both modes were optimized and applied for the extraction of benzene and xylenes from different aqueous samples. All effective parameters including extraction time, salt content, stirring rate, and desorption time were optimized. The optimized CF-HS-SPME combined with GC-FID showed good limit of detections (LODs) (0.3–2.3 μg/L), limit of quantifications (LOQs) (1.0–7.0 μg/L) and linear ranges (1.0–5000 μg/L). The developed method was applied for the analysis of benzene and xylenes in rainwater and some wastewater samples.  相似文献
7.
In this work, a novel homogeneous assay for DNA quantitative analysis based on förster resonance energy transfer (FRET) was developed for cauliflwer mosaic virus 35s (CaMV35S) promoter of transgenic soybean detection. The homogenous FRET of fluorescence signal was fabricated by DNA hybridization with probe modified nitrogen-doped graphene quantum dots (NGQDs) and silver nanoparticles (AgNPs), which acted the donor-acceptor pairs for the first time. The highly efficient FRET and unique properties of the NGQDs made the proposed FRET system as a functionalized detection platform for labelling of DNA. Upon the recognition of specific target DNA (tDNA), the FRET between NGQDs and AgNPs was triggered to produce fluorescence quenching, which could be used for tDNA detection. The fabricated homogeneous FRET assay displayed a wide linear range of 0.1–500.0 nM and a low limit of detection 0.03 nM for the detection of CaMV35S (S/N = 3). This proposed biosensor revealed high specificity to detect tDNA, with acceptable intra-assay precision and excellent stability. This method was successfully applied to identify the real sample of 0.5% containing transgenic soybean, which achieved the most of national law regulations. This assay was further validated by polymerase chain reaction as the genetically modified organisms, suggesting that the proposed FRET system is a feasible tool for the further daily genetically modified organism detection.  相似文献
8.
Graphene field-effect transistors (GFET) have emerged as powerful detection platforms enabled by the advent of chemical vapor deposition (CVD) production of the unique atomically thin 2D material on a large scale. DNA aptamers, short target-specific oligonucleotides, are excellent sensor moieties for GFETs due to their strong affinity to graphene, relatively short chain-length, selectivity, and a high degree of analyte variability. However, the interaction between DNA and graphene is not fully understood, leading to questions about the structure of surface-bound DNA, including the morphology of DNA nanostructures and the nature of the electronic response seen from analyte binding. This review critically evaluates recent insights into the nature of the DNA graphene interaction and its affect on sensor viability for DNA, small molecules, and proteins with respect to previously established sensing methods. We first discuss the sorption of DNA to graphene to introduce the interactions and forces acting in DNA based GFET devices and how these forces can potentially affect the performance of increasingly popular DNA aptamers and even future DNA nanostructures as sensor substrates. Next, we discuss the novel use of GFETs to detect DNA and the underlying electronic phenomena that are typically used as benchmarks for characterizing the analyte response of these devices. Finally, we address the use of DNA aptamers to increase the selectivity of GFET sensors for small molecules and proteins and compare them with other, state of the art, detection methods.  相似文献
9.
In this paper, the highly intrinsic peroxidase-like catalytic activity of nitrogen-doped graphene quantum dots (N-GQDs) is revealed. This activity was greatly dependent on pH, temperature and H2O2 concentration. The experimental results showed that the stable N-GQDs could be used for the detection of H2O2 and glucose over a wide range of pH and temperature, offering a simple, highly selective and sensitive approach for their colorimetric sensing. The linearity between the analyte concentration and absorption ranged from 20 to 1170 μM for H2O2 and 25 to 375 μM for glucose with a detection limit of 5.3 μM for H2O2 and 16 μM for glucose. This assay was also successfully applied to the detection of glucose concentrations in diluted serum and fruit juice samples.  相似文献
10.
A novel nonenzymatic sandwich-type electrochemical immunosensor has been developed to detect squamous cell carcinoma antigen (SCCA). Nitrogen-doped graphene sheet (N-GS) was used to increase capacity of capturing primary antibodies (Ab1). Carbon-supported Pd–Au binary nanoparticles (Pd–Au/C) were synthesized and used to label secondary antibodies (Ab2). The specific binding of SCCA and antibodies enabled a quantitative attachment of Pd–Au/C on the electrode surface. Electrocatalytic analysis showed that the prepared Pd–Au/C exhibit excellent electrocatalytic activity towards hydrogen peroxide (H2O2). We use current response of electrocatalytic labels Pd–Au/C to detect the concentration of SCCA. The unique nonenzymatic immunosensor exhibits a relatively wide linear range from 0.005 to 2 ng mL−1 and high sensitivity with a low detection limit of 1.7 pg mL−1. The immunsensor also shows good reproducibility (4.2%) and stability (5.8%), which makes it an enormous application prospect in clinical research.  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号