XPS study of early stages of Al/Au interface formation

The interface formation between Au polycrystalline substrate kept at temperature of liquid nitrogen and Al deposit and its evolution during sample thermal treatments have been investigated by means of XPS. The intermixing of the Al and Au atoms at the interface occurred readily already at temperature of liquid nitrogen and resulted in the appearance of well‐resolved components on the high‐binding‐energy side of the Au(4f) spectra assignable to AlAu intermetallic phase. The sample annealing resulted in the growth of the amount of intermetallic compound formed at liquid nitrogen temperature. The formation of the initial AlAu phase at the Al/Au interface in our experimental conditions can be explained on the basis of its thermodynamic stability. Copyright © 2009 John Wiley & Sons, Ltd.     

A review of linear carbon chains

Linear carbon chains (LCCs) are a one-dimensional sp¹-hybridized allotrope of carbon. LCCs are extremely unstable: The longer the LCCs, the less stable the materials. Thus, it is a big challenge to synthesize long LCCs. Although the research on the short LCCs, e.g., polyynes, can be traced back to the 18^th, LCCs are still not well-known compared to other allotropes of carbon, e.g., fullerenes, carbon nanotubes and graphene. Therefore, introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general. Theoretically, various excellent properties have been predicted. Experimentally, LCCs with different length in many kinds of forms have been successfully synthesized. In this review, we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects. Also, perspectives are highlighted to point out the further investigations of the materials.     

二维金纳米粒子结构的制备及影响因素

用电泳沉积方法制备了金纳米粒子的二维排列结构。研究了电场强度、沉积时间、溶胶浓度、温度和方波脉冲等对沉积结构的影响。提高外加电场强度和旋加方波脉冲可以提高金粒子结构的有序性。粒子浓度减小,温度升高不利于粒子的电泳沉积。     

Au/L-Met/GC电极的H2O2电催化氧化

在无额外的添加剂和保护剂的情况下,以柠檬酸钠还原氯金酸制得链状金纳米粒子,使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察样品. 层层自组装技术可将金纳米粒子自组装,并分别以L-甲硫氨酸（L-Methionine,L-Met）、硫脲（Thiourea,TU）、丙烯基硫脲（Allyl thiourea,ATU）和聚乙烯吡咯烷酮（Polyvinylpyrrolidone,PVP）交联剂自组装于玻碳基底,即得金纳米粒子修饰电极. 以[Fe(CN)₆]^3-/4-氧化还原电对为探针,考察该修饰电极的电化学性质. Au/L-Met/GC电极有最佳电化学性能,循环伏安曲线和计时电流曲线测试表明,Au/L-Met/GC电极的H₂O₂电催化氧化有较高的灵敏度,线性范围2×10^-7 ~ 3×10^-3 mol·L^-1,检出限6.67×10^-8 mol·L^-1.     

Theoretical studies on structures and electronic spectra of linear carbon chains C2nH+ (n = 1−5)

The density functional theory (DFT) and the complete active space self‐consistent‐field (CASSCF) method have been used for full geometry optimization of carbon chains C_2nH⁺ (n = 1–5) in their ground states and selected excited states, respectively. Calculations show that C_2nH⁺ (n = 1–5) have stable linear structures with the ground state of X³Π for C₂H⁺ or X³Σ^? for other species. The excited‐state properties of C_2nH⁺ have been investigated by the multiconfigurational second‐order perturbation theory (CASPT2), and predicted vertical excitation energies show good agreement with the available experimental values. On the basis of our calculations, the unsolved observed bands in previous experiments have been interpreted. CASSCF/CASPT2 calculations also have been used to explore the vertical emission energy of selected low‐lying states in C_2nH⁺ (n = 1–5). Present results indicate that the predicted vertical excitation and emission energies of C_2nH⁺ have similar size dependences, and they gradually decrease as the chain size increases. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

有序介孔碳CMK-3负载金纳米微粒复合材料的制备和表征

分别采用等体积浸渍-甲醛还原、等体积浸渍-氢气还原及溶胶负载法在介孔碳CMK-3上负载金纳米微粒;利用透射电镜和粉末X射线衍射仪对比分析了采用3种方法得到的复合材料的微结构和相组成;并测定了采用溶胶负载法得到的不同金含量的复合材料的热稳定性.结果表明,所制备的金纳米微粒的尺寸因制备方法不同而呈现明显差异;负载于复合材料中的金纳米微粒具有很好的热稳定性.     

Bulk synthesis of linear carbon chains confined inside single-wall carbon nanotubes by vacuum discharge

Carbyne, an infinite carbon chain, has attracted much interest and induced significant controversy for many decades. Recently, the presence of linear carbon chains (LCCs), which were confined stably inside double-wall carbon nanotubes (DWCNTs) and multiwall carbon nanotubes (MWCNTs), has been reported. In this study, we present a novel method to produce LCCs in a film of carbon nanotubes (CNTs). Our transmission electron microscopy and Raman spectroscopy revealed the formation of a bulk amount of LCCs after electric discharge of CNT films, which were used as field emission cathodes. The LCCs were confined inside single-wall CNTs as well as DWCNTs. Furthermore, two or three LCCs in parallel with each other are encapsulated when the inner diameter of CNT is larger than approximately 1.1 nm.     

Solvent effect on the synthesis of monodisperse amine-capped Au nanoparticles

A remarkable solvent effect in a single-phase synthesis of monodisperse amine-capped Au nanoparticles is demonstrated.Oleylamine-capped Au nanoparticles were prepared via the reduction of HAuCU by an amine-borane complex in the presence of oleylamine in an organic solvent.When linear or planar hydrocarbon(e.g.,n-hexane,n-octane,1-octadecylene,benzene,and toluene) was used as the solvent, high-quality monodisperse Au nanoparticles with tunable sizes were obtained.However,Au nanoparticles with poor size dispersity were obtained when tetralin,chloroform or cyclohexane was used as the solvent.The revealed solvent effect allows the controlled synthesis of monodisperse Au nanoparticles with tunable size of 3-10 nm.     

Unconventional chain-growth mode in the assembly of colloidal gold nanoparticles

One-dimensional assembly of gold nanoparticlesis achieved by a sphere-to-cylinder transformation of polymer shells. A large amount of monomers remains after the assembly, which is characteristic of the chain-growth "polymerization". Single-line chains can be converted to double-line chains, thus substantiating the unique role of the polymer shell.     

金催化CO氧化湿度增强效应的理论研究

实验发现纳米金催化的CO氧化有良好的湿度增强效应,但有关机制仍不清楚.我们应用密度泛函理论研究了湿度增强效应的微观机制,以Au4团簇为例,研究了金催化CO氧化的微观机理,考察了H2O在反应中的角色和作用.计算结果表明,H2O与Au4团簇一样,在反应中扮演催化剂的角色,参与反应的进行、改变反应历程、降低反应能垒.催化循环包含4个基元步骤：O2＋H2O→OOH＋OH,CO＋OOH→CO2＋OH,CO＋OH→COOH,和COOH＋OH→CO2＋H2O,其中自由基OOH和OH的形成是催化循环的速控步骤,其能垒为100.31kJ/mol,明显低于非水参与反应的能垒（161.41kJ/mol）.目前的结果合理地解释了实验观测的CO催化氧化的湿度增强效应,给出了其微观反应机制.     

Bond length features of linear carbon chains of finite to infinite size: Visual interpretation from Pauling bond orders

Schemes for Kekulé structure counting of linear carbon chains are suggested. Mathematical formulas, which calculate the Pauling bond order P(k, N) of a chemical bond numbered by k, are given for the carbon chain with N carbon atoms. By use of the least‐squares fitting of a linearity, relationships between Pauling bond orders and bond lengths are obtained, and such correlation of the Pauling bond order–bond length can be qualitatively extended to the excited states. The relative magnitudes of Pauling bond orders in unsaturated carbon chains dominate C–C bond lengths a well as the bond length feature with the chain size increasing. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 144–149, 2003     

Green synthesis of plant-stabilized Au nanoparticles for the treatment of gastric carcinoma

In this study, gold nanoparticles (AuNPs) were green synthesized using plant extract. The obtained nanoparticles (Au NPs) were characterized by advanced physical and chemical techniques like TEM, FTIR, UV–vis, SEM, XRD and EDX. SEM image displayed the quasi-spherical shaped nanoparticles of mean diameter 20–50 nm. All the particles were of uniform shape and texture. From the XRD pattern, four distinct diffraction peaks at 38.2°, 44.2°, 64.7° and 77.4° are indexed as (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes of fcc metallic gold. The in vitro cytotoxic and anti-gastric carcinoma effects of biologically synthesized Au NPs against cancer cell lines were assessed. The IC₅₀ of the Au NPs were 192, 149, 76 and 85 µg/mL against NCI-N87, MKN45, GC1401 and GC1436 gastric cancer cell lines. The anti-gastric carcinoma properties of the Au NPs could significantly remove the cancer cell lines in a time and concentration-dependent manner. So, the findings of the recent research show that biologically synthesized Au NPs might be used to cure cancer.     

The use of imaging XPS to assess ligand binding to nanoparticles

A micro‐beam scanning X‐ray photoelectron spectroscopy (XPS) has been utilized to obtain information about the attachment of ligand to nanoparticles in solution by measuring the ligand components relative to nanoparticle components. CdSe/ZnS core/shell nanoparticles capped with three different kinds of ligand molecules are drop‐casted on a substrate and led to dry into self‐agglomerated micropatterns. Those specimens are mapped out by element‐sensitive XPS imaging. The spatial correlation between surface ligand molecules and core nanoparticle atoms is statistically analysed using Pearson correlation function, which provides with a useful assessment of the ligand binding to nanoparticle surfaces. Copyright © 2014 John Wiley & Sons, Ltd.     

Detection and distinguishability of leukemia cancer cells based on Au nanoparticles modified electrodes

The Au nanoparticles (Au NPs) modified interface has been fabricated by multi-potential step electrodeposition in this study. Based on the nano-Au interface, we have proposed an electrochemical approach to detect the cancer cell numbers sensitively with a detection limit of about 500 cells. More interestingly, the drug sensitive leukemia K562 cells and drug resistant leukemia K562/adriamycin could be electrochemically distinguished on the interface by the oxidation potential, which did not show any evident differences on the bare electrode. These results indicate the promising application of this nano-interface for constructing the unlabeled potential-discriminative cell biosensors.     

Interaction between electronic and nuclear motion in linear chains

Summary The geometrical structure of linear chains is discussed with reference to procedures for treating both electronic and nuclear motion and illustrated with reference to recent density functional calculations.     

Capillary electrophoretic study of green fluorescent hollow carbon nanoparticles

CE coupled with laser‐induced fluorescence and UV absorption detections has been applied to study the complexity of as‐synthesized green fluorescent hollow carbon nanoparticles (HC‐NP) samples. The effects of pH, type, and concentration of the run buffer and SDS on the separation of HC‐NP are studied in detail. It is observed that phosphate run buffer is more effective in separating the HC‐NP and the optimal run buffer is found to be 30 mM phosphate and 10 mM SDS at pH 9.0. The CE separation of this HC‐NP is based on the difference in size and electrophoretic mobility of HC‐NP. Some selected HC‐NP fractions are collected and further characterized by UV‐visible absorption and photoluminescence (PL) spectroscopy, MS, and transmission electron microscopy. The fractionated HC‐NP show profound differences in absorption, emission characteristics, and PL quantum yield that would have been otherwise misled by studying the complex mixture alone. It is anticipated that our CE methodology will open a new initiative on extensive studies of individual HC‐NP species in the biomedical, catalysis, electronic, and optical device, energy storage, material, and sensing field.     

Spectrophotometric and physicochemical investigations of Congo,alizarin red dyes and BSA interactions with Au,Ag and Au/Ag mix nanoparticles,and their antimicrobial activities

Individual and mix metal nanoparticles of Ag and Au have been prepared by the reducing method where citrate was used as reducing/stabilizing agent. The prepared NPs were characterized with UV/Visible and transmission electron microscopic (TEM) tools. The characteristic peak in UV/Visible at 525, 444 and 531 nm for Au, Ag and Ag/Au mix NPs respectively, gave primary confirmation of prepared NPs. TEM analysis showed the size of nanoparticles as 44.04, 19.78 and 30.93 nm for Ag, Au and Ag/Au mix NPs respectively. Congo and alizarin red dye interactions studies have been performed with prepared NPs to see the removal of the pollutants from water. Congo dye has shown weaker interaction as compared to alizarin due to structural symmetry. Amongst all, the AgNPs have shown maximum 67% and 75% interactions with Congo red and alizarin respectively due to high negative charges on the surface. The Au, Ag and Au/Ag mix NPs have shown stronger interaction with bovine serum albumin (BSA) protein up to 51, 59, 55% respectively, estimated through UV/Vis and physicochemical analysis. The biological evaluations of the prepared NPs have shown their antibacterial activity against Gram + ve and –ve species showing up to 9 cm zone of inhibition. The BSA interaction and antibacterial activity of NPs reveal the importance of NPs in medicinal field.     

Probing the interfacial interaction between monolayer molybdenum disulfide and Au nanoclusters

Coupling of plasmonic metal nanostructures on two‐dimensional materials represents one promising approach to improve their optoelectronic device performance. In this article, we systematically investigated the interfacial interactions between Au nanoclusters and monolayer molybdenum disulfide (MoS₂) and the effect of Au decoration on the electrical transport and optical properties of MoS₂, through the combination of in situ MoS₂ field‐effect transistor device evaluation and in situ ultraviolet photoelectron spectroscopy and X‐ray photoelectron spectroscopy measurements. The in situ X‐ray photoelectron spectroscopy/ultraviolet photoelectron spectroscopy experiments revealed a weak interfacial coupling between Au nanoclusters and monolayer MoS₂. The absence of strong charge transfer between Au nanoclusters and MoS₂ was further confirmed by the photoluminescence and Raman measurements. It was also found that the electron charge‐carrier concentration in monolayer MoS₂ weakly depended on the coverage of Au nanoclusters. Copyright © 2017 John Wiley & Sons, Ltd.     

Sensitive determination of hydrazine using poly(phenolphthalein), Au nanoparticles and multiwalled carbon nanotubes modified glassy carbon electrode

This study reports a detailed analysis of an electrode material containing poly(phenolphthalein), carbon nanotubes and gold nanoparticles which shows superior catalytic effect towards to hydrazine oxidation in Britton–Robinson buffer (pH 10.0). Glassy carbon electrode was modified by electropolymerization of phenolphthalein (PP) monomer (poly(PP)/GCE) and the multiwalled carbon nanotubes (MWCNTs) was dropped on the surface. This modified surface was electrodeposited with gold nanoparticles (AuNPs/CNT/poly(PP)/GCE). The fabricated electrode was analysed the determination of hydrazine using cyclic voltammetry, linear sweep voltammetry and amperometry. The peak potential of hydrazine oxidation on bare GCE, poly(PP)/GCE, CNT/GCE, CNT/poly(PP)/GCE, and AuNPs/CNT/poly(PP)/GCE were observed at 596 mV, 342 mV, 320 mV, 313 mV, and 27 mV, respectively. A shift in the overpotential to more negative direction and an enhancement in the peak current indicated that the AuNPs/CNT/poly(PP)/GC electrode presented an efficient electrocatalytic activity toward oxidation of hydrazine. Modified electrodes were characterized with High-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Amperometric current responses in the low hydrazine concentration range of 0.25–13 µM at the AuNPs/CNT/poly(PP)/GCE. The limit of detection (LOD) value was obtained to be 0.083 µM. A modified electrode was applied to naturel samples for hydrazine determination.     

无电沉积法AuNPs-MWCNTs的制备及其对黄酮类化合物的电化学催化性能研究

利用多壁碳纳米管具有较低的还原电位,以多壁碳纳米管作为还原剂和负载基底,通过无电沉积法制备了负载纳米金粒子的碳纳米管催化剂。此种材料具有更多的活性位点,避免了纳米金粒子表面保护剂的存在造成其催化活性降低的缺陷,发现其对典型黄酮类化合物-芦丁和黄芩苷具有良好的电化学催化性能和较高的灵敏度,并将其应用于电化学分析检测黄酮类化合物。