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31.
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以铌箔为基底,用阳极氧化法结合氨气还原氮化法制备出氮化铌纳米管,利用X射线衍射仪(XRD)、X射线光电子能谱(XPS)和扫描电镜(SEM)等结构表征手段和循环伏安法(CV)、充放电(GCD)和交流阻抗法(EIS)等电化学测试手段研究了还原氮化温度对纳米管的物相、形貌以及电化学性能的影响.结果表明,还原氮化后出现了氮化铌物相,以氧氮化铌固溶体形式存在,当还原氮化温度为700℃时,氮化铌纳米管阵列结构均匀,纳米管的孔内径约为35 nm,管壁厚度约为12 nm,纳米管长度约为1.5μm,样品中内在阻抗和电荷转移电阻较小,在电流密度为0.1 mA/cm2时,其比电容为400μF/cm2. 相似文献
34.
近年来,半导体量子点特别是InAs量子点的基本物理性质和潜在应用得到了广泛研究。许多研究者利用InAs量子点结构的改变以调制其光电特性。本文采用液滴外延法在GaAs(001)表面沉积了不同沉积量的In(3 ML、4 ML、5 ML),以研究In的成核机制和表面扩散。实验发现,随着In沉积量的增加,液滴尺寸(包括直径、高度)明显增大。不仅如此,在相同的衬底温度下,沉积量越大,液滴密度越大。利用经典成核理论,计算了GaAs(001)表面In液滴形成的临界厚度为0.57 ML,计算的结果与已报道的实验一致。从In原子在表面的迁移和扩散,以及衬底中Ga和液滴中的In之间的原子互混原理解释了In液滴形成和形貌演化的机理。实验中得到的In液滴临界厚度以及In液滴在GaAs(001)上成核机理,可以为制备InAs量子点提供实验指导。 相似文献
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Three novel amphiphilic poly(ionic liquid) (PIL)/Wells–Dawson-type phosphovanadomolybdate (V-POM) ionic composites with tunable oxidative catalytic activity and unique nanostructure were synthesized using carboxylic acid-functionalized PIL and H7[P2Mo17VO62], H8[P2Mo16V2O62] and H9[P2Mo15V3O62] as synthetic units via self-assembly in water. The results of characterization indicated that V-POM anions were finely dispersed in the PIL cation framework, and their structures were well preserved. The three composites are amorphous V-POM salts of PIL cation with a considerable thermal stability, and an open three-dimensional network structure with hierarchical porosity. The as-synthesized composites were found to be efficient heterogeneous catalysts for the direct hydroxylation of benzene to phenol with H2O2 in the liquid phase. Under optimum conditions, a phenol yield of 37.3% was achieved with selectivity of 100%. The high catalytic performance could be attributed to the synergistic catalytic effect between V-POM anion and carboxylic acid-functionalized PIL cation framework, and good benzene adsorption and phenol desorption ability of amphiphilic micropores in the structure of the composites. Additionally, these composites exhibited high stability under the reaction conditions and could be easily recovered and reused at least six times without noticeably loss of activity. 相似文献
37.
研究了基于G-N模型与三项延迟模型的热弹性波的传播特征.在各种广义热弹性理论中,热位移概念的引入使得G-N模型具有独特性质而引起广泛的关注和应用.基于G-N模型,最近一个三相延迟模型被提出.主要研究了这两种模型下第一和第二声波(耦合热弹性波)的色散和衰减特性,分析了温度场和位移场在两种模型下的振幅比和相位差.结果发现三相延迟模型更为通用和灵活,应得到更多的关注与应用. 相似文献
38.
ZHANG Xinyu TANG Pengpeng ZHAI Guangyao LIN Xiu ZHANG Qiang CHEN Jiesheng WEI Xiao 《高等学校化学研究》2022,38(5):1292-1300
In this study, we have provided a facile solution to synthesize well-aligned titanium dioxide nanorods by using hydrothermal reaction. By calcining the materials under different atmospheres and temperatures, a batch of titanium dioxides with excellent oxygen evolution reaction(OER) catalytic efficiency were obtained. This new structured TiO2 photoanode material yields a high photocurrent density of 5.69 mA/cm2 at 1.23 V vs. reversible hydrogen electrode(RHE) under simulated solar light(100 mW/cm2). Surface photovoltage techniques and other measurements were carried out to confirm that the enhanced photoelectrochemical performances were attributed to the synergistic effect of the phase junction and a certain content of surface states, which accelerate the separation and transmission of the photogenerated charges. This material with phase junction and surface states promises a potential application in the field of photoelectric catalysis under solar light. 相似文献
39.
Redox graphene-MXene(rGO-MXene) nanocomposites were prepared by ion polymerization and used to construct a highly sensitive electrochemical sensor for baicalin(BA) detection. The synergistic effect of rGO and MXene increased the specific surface area and electron transport capacity of the electrode, and significantly enhanced the electrochemical response of BA. The cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of BA on the sensor. Under the optimal conditions, the peak current exhibited a good linear relationship with BA concentration in the range of 0. 05-10 μmol / L, and the limit of detection was as low as 28 nmol / L. The method was applied to analyze traditional Chinese medicine preparations containing baicalin, such as Qingkailing Capsule and Sanhuang Tablets with good accuracy and spiked recovery. The results were highly consistent with those of high performance liquid chromatography, providing a technical means for the rapid and sensitive detection of traditional Chinese medicine preparations. © 2022, Youke Publishing Co.,Ltd. All rights reserved. 相似文献
40.
半导体光催化制氢是一种可实现持续制备和储存氢气的绿色技术.石墨相氮化碳(g-C3N4)是研究广泛的光催化剂,但其仍存在光利用率低、光生电子和空穴易复合等问题,制约着光催化产氢的性能.利用给电子卟啉修饰g-C3N4,构建了四(4-羧基)苯基卟啉(TCPP)以共价/非共价方式修饰g-C3N4的催化剂.卟啉共价修饰g-C3N4(gC3N4-TCPP0.1)及非共价复合结构(TCPP0.1/g-C3N4)光催化产氢速率分别为6 997和5 399μmol·g-1·h-1,较g-C3N4分别提高了53%和18%. TCPPx/g-C3N4异质结加强了界面接触,促进了电荷转移,增强了可见光吸收能力,进而提高了光催化制氢性能. g-C3N4-TCPPx中, TCPP的接枝拓展了共轭结构,优化了电子结构,增大了分子偶极,促进了电荷分离,共价桥键为电荷传输提供了通道. 相似文献