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61.
以抗坏血酸为还原剂、聚乙烯吡咯烷酮（PVP）为模板分子,合成了PVP稳定的铜纳米簇（PVP-Cu NCs）。利用谷胱甘肽（GSH）对PVP-Cu NCs荧光信号的增强作用,建立了非标记检测GSH的新方法。该方法对GSH检测的线性范围为30~800 μmol/L,检出限为1.2 μmol/L,具有较好的选择性。PVP-Cu NCs与GSH的作用机理为配体交换,GSH与Cu原子配位形成了更稳定的Cu—S键。该方法应用于药片中GSH的测定,取得了满意的结果。 相似文献
62.
以D-色氨酸为保护剂和还原剂, 采用水热法快速制备了具有强荧光的金纳米簇(D-Trp@AuNCs); 以其作为荧光探针, 建立了基于荧光猝灭的选择性高灵敏检测Fe3+的传感方法. 利用透射电子显微镜(TEM)、 紫外-可见光谱(UV-Vis)和红外光谱(IR)等手段对制备的金纳米簇进行了表征, 并利用荧光光谱研究了D-Trp@AuNCs的荧光性能. 结果表明, D-Trp@AuNCs具有较好的生物相容性, 其最大激发波长为370 nm, 最大发射波长为460 nm; 向金纳米簇溶液中加入Fe3+后, D-Trp@AuNCs的荧光发生明显猝灭, 其猝灭程度与Fe3+的浓度在0.3~500.0 μmol/L范围内呈现良好的线性关系, 检出限为33.1 nmol/L(S/N=3). 将该荧光探针用于实际水样中Fe3+的检测, 回收率为86.6%~106.5%. 相似文献
63.
Andrey A. Buglak Vladimir A. Pomogaev Alexei I. Kononov 《International journal of quantum chemistry》2019,119(20):e25995
The detailed structures of most of ligand-stabilized metal nanoclusters (NCs) remain unknown due to the absence of crystal structure data for them. In such a situation, quantum-chemical modeling is of particular interest. We compared the performance of different theoretical methods of geometry optimization and absorption spectra calculation for silver-thiolate complexes. We showed that the absorption spectra calculated with the ADC(2) method were consistent with the spectra obtained with CC2 method. Three DFT functionals (B3LYP, CAM-B3LYP, and M06-2X) failed to reproduce the CC2 absorption spectra of the silver-thiolate complexes. 相似文献
64.
65.
Mengyao Lv Ying Zhou Sefiu Abolaji Rasaki Hangjia Shen Chuanxi Wang Weiyu Song Tiju Thomas Dr. Minghui Yang Jun Wang 《ChemElectroChem》2019,6(22):5744-5749
Water electrolysis has received tremendous interest for energy conversion. This is due to its intrinsic eco-friendliness, and plausibly high efficiencies. However, the efficiency is hampered by sluggish kinetics of the oxygen evolution reaction (OER) at the anode. In this work, co-precipitation method followed by nitridation is used for fabricating highly efficient and stable Au-decorated Ni3N electrocatalyst for OER activity in alkaline solution. The as-prepared 2 wt % Au at Ni3N (2 %Au/Ni3N) nanoflower exhibits remarkable OER. Current density of 10 mA cm−2, Tafel slope of 52 mV/dec, a relatively small overpotential of ∼280 mV, and 94.8 % activity retention for over 10 hour of continuous operation are observed. This remarkable performance is one of the best OER results known so far for noble metal-supported nanostructured materials using alkaline solution as the electrolyte. From experimental results and calculations thereby, it is found that the Au nanocluster can effectively regulate Ni3N electronic structure, and reduce the energy barrier associated with OER activity. The synthesis approach given here not only provides a highly efficient electrocatalyst for energy conversion, but also offers a platform for controlling structural characteristics, thereby tuning the catalytic properties of the Au/Ni3N nanoflowers. 相似文献
66.
Zhong-hu Liu Xing Chen Yi-yu Zhu Si-han Zhao Zhi-qiang Wang Feng Wang Qiang-qiang Meng Lei Zhu Qin-fang Zhang Bao-lin Wang Le-le Fan 《化学物理学报(中文版)》2019,32(2):248-252
Tin dioxide (SnO2) has attracted broad interest due to its particular gas-sensor property. Nano- or atom-scale SnO2 material has always been the aim in order to ultimately improve the sensitivity. However, until now, it remains difficult to synthesize SnO2 nanoclusters by using traditional methods. In the present work, we have achieved the preparation of SnO2 nanoclusters by using the cluster beam deposition technique. The obtained nanoclusters were well characterized by high resolution transmission electron microscope HR-TEM. Results indicated the formation of the well-dispersed SnO2 nanoclusters with uniform size distribution (5-7 nm). Furthermore, an obvious metal insulator transition was observed by gating with ionic liquid. Combined with theory calculation, the corresponding mechanism was systematically analyzed from oxygen vacancy induced electron doping. 相似文献
67.
Isomerism of atomically precise noble metal nanoclusters provides an excellent platform to investigate the structure–property correlations of metal nanomaterials. In this study, we performed density functional theory (DFT) and time‐dependent (TD‐DFT) calculations on two Au21(SR)15 nanoclusters, one with a hexagonal closed packed core (denoted as Au21 hcp ), and the other one with a face‐centered cubic core (denoted as Au21 fcc ). The structural and electronic analysis on the typical Au–Au and Au–S bond distances, bond orders, composition of the frontier orbitals and the origin of optical absorptions shed light on the inherent correlations between these two clusters. 相似文献
68.
Akhtar Munir Prof. Khurram Saleem Joya Tanveer Ul haq Noor-Ul-Ain Babar Syed Zajif Hussain Dr. Ahsanulhaq Qurashi Dr. Najeeb Ullah Prof. Irshad Hussain 《ChemSusChem》2019,12(8):1517-1548
A sustainable future demands innovative breakthroughs in science and technology today, especially in the energy sector. Earth-abundant resources can be explored and used to develop renewable and sustainable resources of energy to meet the ever-increasing global energy demand. Efficient solar-powered conversion systems exploiting inexpensive and robust catalytic materials for the photo- and photo-electro-catalytic water splitting, photovoltaic cells, fuel cells, and usage of waste products (such as CO2) as chemical fuels are appealing solutions. Many electrocatalysts and nanomaterials have been extensively studied in this regard. Low overpotentials, catalytic stability, and accessibility remain major challenges. Metal nanoclusters (NCs, ≤3 nm) with dimensions between molecule and nanoparticles (NPs) are innovative materials in catalysis. They behave like a “superatom” with exciting size- and facet-dependent properties and dynamic intrinsic characteristics. Being an emerging field in recent scientific endeavors, metal NCs are believed to replace the natural photosystem II for the generation of green electrons in a viable way to facilitate the challenging catalytic processes in energy-conversion schemes. This Review aims to discuss metal NCs in terms of their unique physicochemical properties, possible synthetic approaches by wet chemistry, and various applications (mostly recent advances in the electrochemical and photo-electrochemical water splitting cycle and the oxygen reduction reaction in fuel cells). Moreover, the significant role that MNCs play in dye-sensitized solar cells and nanoarrays as a light-harvesting antenna, the electrochemical reduction of CO2 into fuels, and concluding remarks about the present and future perspectives of MNCs in the frontiers of surface science are also critically reviewed. 相似文献
69.
Akhtar Munir Tanveer ul Haq Iqtidar Hussain Prof. Ahsanulhaq Qurashi Ubaid Ullah Javed Iqbal Prof. Irshad Hussain 《ChemSusChem》2019,12(23):5117-5125
Metal nanoclusters (NCs, size ≤2 nm) are emerging materials in catalysis owing to their unique catalytic and electronic properties such as high surface/volume ratio, high redox potential, plethora of surface active sites, and dynamic behavior on a suitable support during catalysis. Herein, in situ growth of ultrasmall and robust Co@β-Co(OH)2 NCs (≈2 nm) hosted in a honeycomb-like 3D N-enriched carbon network was developed for water-oxidation catalysis with extremely small onset potential (1.44 V). Overpotentials of 220 and 270 mV were required to achieve a current density of 10 mA cm−2 and 100 mA cm−2, respectively, in alkaline medium (1 m KOH). More promisingly, at η10=240 mV, the prolonged oxygen evolution process (>130 h) with faradaic efficiency >95 % at a reaction rate of 22 s−1 at 1.46 V further substantiated the key role of the ultrasmall supported NCs, which outperformed the benchmark electrocatalysts (RuO2/IrO2) and NCs reported so far. It is anticipated that the high redox potential of NCs with regeneratable active sites and their concerted synergistic effects with the N-enriched porous/flexible carbon network are inherently worth considering to enhance the mass/charge transport owing to the nanoscale interfacial collaboration across the electrode/electrolyte boundary, thereby efficiently energizing the sluggish/challenging oxygen evolution process. 相似文献
70.
The vacancy-type defects and their local chemical environment in different ODS alloys produced in the USA (14YWT), China (K5) and Russia (ODS EP-450) are studied. The Angular Correlation of Annihilation Radiation (ACAR), which is one of the positron annihilation spectroscopy method, was used. It was shown that in all alloys, except 14YWT, the dominant type of positron traps are vacancy-like defects, localised in matrix or associated with dislocations and/or interfaces of the incoherent particles. In the case of 14YWT alloy, which contains Y–Ti–O nanoclusters of a high density, the positrons confine and annihilate at O-vacancy pairs or complexes within nanoclusters. It is testified by enhanced electron density in annihilation sites and neighbourhood of Ti and Y atoms. These results, obtained by the ACAR method, indicate that the vacancies play an essential role in the formation of nanoclusters in ODS 14YWT alloy as it was theoretical predicted by first-principle calculations. 相似文献