高择优锌—镍合金电沉积的现场ECSTM研究

采用“二步包封”法制备了性能良好的电化学ＳＴＭ针尖。以此为基础采用ＥＣＳＴＭ现场研究了工艺条件下ＨＯＰＧ上高择优锌－镍合金的电沉积过程。研究结果表明这种高铎优沉积层以侧向生长方式生长，而表面上电化学活性差的晶面构成了晶体生长过程的保留面，从而进一步形成了与基底表面方向一致的高择优沉积层，Ｘ射线研究表明这一择优面为（１００）晶面。     

SYNTHESIS AND CRYSTAL STRUCTURE OF THE CLUSTER COMPOUND MoS_4Cu_2Ag（Ph_3P）_3Br．H_2O

ＳＹＮＴＨＥＳＩＳ ＡＮＤ ＣＲＹＳＴＡＬ ＳＴＲＵＣＴＵＲＥ ＯＦ ＴＨＥ ＣＬＵＳＴＥＲ ＣＯＭＰＯＵＮＤ ＭｏＳ_４Ｃｕ_２Ａｇ（Ｐｈ_３Ｐ）_３Ｂｒ．Ｈ_２Ｏ￥ＤｅＬｉａｎｇＬＯＮＧ；ＸｉｎＱｕａｎＸＩＮ（ＳｔａｌｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆ?..     

STUDIES ON THE DECOMPOSITION OF H_2O INTO H_2 WITH OXYGEN-DEFICIENT MAGNETITE

ＳＴＵＤＩＥＳ　ＯＮ　ＴＨＥ　ＤＥＣＯＭＰＯＳＩＴＩＯＮ　ＯＦ　Ｈ_２Ｏ　ＩＮＴＯ　Ｈ_２　ＷＩＴＨ　ＯＸＹＧＥＮ－ＤＥＦＩＣＩＥＮＴ　ＭＡＧＮＥＴＩＴＥＳＴＵＤＩＥＳＯＮＴＨＥＤＥＣＯＭＰＯＳＩＴＩＯＮＯＦＨ_２ＯＩＮＴＯＨ_２ＷＩＴＨＯＸＹＧＥＮ－Ｄ...     

SYNTHESIS OF ALLANTOIN USING HETEROPOLY COMPOUNDS AS CATALYSTS

ＳＹＮＴＨＥＳＩＳＯＦＡＬＬＡＮＴＯＩＮＵＳＩＮＧＨＥＴＥＲＯＰＯＬＹＣＯＭＰＯＵＮＤＳＡＳＣＡＴＡＬＹＳＴＳＳＹＮＴＨＥＳＩＳＯＦＡＬＬＡＮＴＯＩＮＵＳＩＮＧＨＥＴＥＲＯＰＯＬＹＣＯＭＰＯＵＮＤＳＡＳＣＡＴＡＬＹＳＴＳ￥ＳｕｉＭｅｉＺＨＡＮＧ；Ｆｅ...     

STUDIES ON DOPAMINE RECEPTORS AND TETRAHYDROPROTOBERBERINES．Ⅱ．QUANTUM CHEMISTRY OF LIGAND－RECEPTOR INTERACTION

ＳＴＵＤＩＥＳＯＮＤＯＰＡＭＩＮＥＲＥＣＥＰＴＯＲＳＡＮＤＴＥＴＲＡＨＹＤＲＯＰＲＯＴＯＢＥＲＢＥＲＩＮＥＳ．Ⅱ．ＱＵＡＮＴＵＭＣＨＥＭＩＳＴＲＹＯＦＬＩＧＡＮＤ－ＲＥＣＥＰＴＯＲＩＮＴＥＲＡＣＴＩＯＮ￥ＹｕｎＴＡＮＧ；ＫａｉＸｉａｎＣＨＥＮ；Ｈｕａ...     

CHEMICAL INCORPORATING PESTICIDES 2．SYNTHESIS OF NEW SUCCINIMIDO ORGANOPHOSPHATES AS POTENTIAL PESTICIDES

ＣＨＥＭＩＣＡＬＩＮＣＯＲＰＯＲＡＴＩＮＧＰＥＳＴＩＣＩＤＥＳ２．ＳＹＮＴＨＥＳＩＳＯＦＮＥＷＳＵＣＣＩＮＩＭＩＤＯＯＲＧＡＮＯＰＨＯＳＰＨＡＴＥＳＡＳＰＯＴＥＮＴＩＡＬＰＥＳＴＩＣＩＤＥＳ￥ＥｒＬｅＺＡＮＧ；ＨｅＨｕｉＺＨＥＮＧ；ＰｉｎｇＬＩ（Ｄｅ...     

LOCAL STRUCTURE OF COPPER IN Cu－ZSM－5 CATALYST FOR NITRIC OXIDE DECOMPOSITION

ＬＯＣＡＬＳＴＲＵＣＴＵＲＥＯＦＣＯＰＰＥＲＩＮＣｕ－ＺＳＭ－５ＣＡＴＡＬＹＳＴＦＯＲＮＩＴＲＩＣＯＸＩＤＥＤＥＣＯＭＰＯＳＩＴＩＯＮ￥ＳｈｕＮｏｎｇＦＡＮＧ；ＹｉＬｕＦＵ；ＰｅｉＹａｎＬＩＮ（Ｄｅｐｔ．ｏｆＣｈｅｍ．Ｐｈｙｓ．，Ｕｎｉｖ．ｏｆＳｃｉ...     

INTERACTION OF AMINO ACID WITH ION EXCHANGERESIN Ⅲ．FURTHER INVESTIGATION OF SUPEREQUIVALENT ADSORPTION MECHANISM OF AMINO ACID ON ION EXCHANGE RESIN

ＩＮＴＥＲＡＣＴＩＯＮＯＦＡＭＩＮＯＡＣＩＤＷＩＴＨＩＯＮＥＸＣＨＡＮＧＥＲＥＳＩＮⅢ．ＦＵＲＴＨＥＲＩＮＶＥＳＴＩＧＡＴＩＯＮＯＦＳＵＰＥＲＥＱＵＩＶＡＬＥＮＴＡＤＳＯＲＰＴＩＯＮ　ＭＥＣＨＡＮＩＳＭＯＦＡＭＩＮＯＡＣＩＤＯＮＩＯＮＥＸＣＨＡＮＧＥ...     

QUANTUM CHEMICAL STUDY ON THE MECHANISM OF PRODUCING OXYGENATES IN FISCHER－TROPSCH SYNTHESIS ON M／SiO＿2 （M＝Ni， Ru， Rh， Pd） CATALYSTS

ＱＵＡＮＴＵＭ　ＣＨＥＭＩＣＡＬ　ＳＴＵＤＹ　ＯＮ　ＴＨＥ　ＭＥＣＨＡＮＩＳＭ　ＯＦ　ＰＲＯＤＵＣＩＮＧ　ＯＸＹＧＥＮＡＴＥＳ　ＩＮ　ＦＩＳＣＨＥＲ－ＴＲＯＰＳＣＨ　ＳＹＮＴＨＥＳＩＳ　ＯＮ　Ｍ／ＳｉＯ＿２　（Ｍ＝Ｎｉ，　Ｒｕ，　Ｒｈ，　Ｐｄ）　ＣＡ...     

RING OPENING POLYMERIZATION OF （CHLOROMETHYL）THIIRANE BY RARE EARTH COORDINATION CATALYSTS Ⅲ．HOMOPOLYMERIZATION OF （CHLOROMETHYL）THIIRANE AND ITS POLYMERIZATION KINETICS

ＲＩＮＧＯＰＥＮＩＮＧＰＯＬＹＭＥＲＩＺＡＴＩＯＮＯＦ（ＣＨＬＯＲＯＭＥＴＨＹＬ）ＴＨＩＩＲＡＮＥＢＹＲＡＲＥＥＡＲＴＨＣＯＯＲＤＩＮＡＴＩＯＮＣＡＴＡＬＹＳＴＳⅢ．ＨＯＭＯＰＯＬＹＭＥＲＩＺＡＴＩＯＮＯＦ（ＣＨＬＯＲＯＭＥＴＨＹＬ）ＴＨＩＩＲＡＮＥ...     

In situ electrochemical scanning tunnelling microscopy investigation of structure for horseradish peroxidase and its electricatalytic property

Immobilization of protein molecules is a fundamental problem for scanning tunnelling microscopy (STM) measurements with high resolution. In this paper, an electrochemical method has been proved to be an effective way to fix native horseradish peroxidase (HRP) as well as inactivated HRP from electrolyte onto a highly oriented pyrolytic graphite (HOPG) surface. This preparation is suitable for both ex situ and in situ electrochemical STM (ECSTM) measurements. In situ STM has been successfully employed to observe totally different structures of HRP in three typical cases: (1) in situ ECSTM reveals an oval-shaped pattern for a single molecule in neutral buffer solution, which is in good agreement with the dimension determined as 6.2×4.3×1.2. nm³ by ex situ STM for native HRP; (2) in situ ECSTM shows that the adsorbed HRP molecules on HOPG in a denatured environment exhibit swelling globes at the beginning and then change into a V-shaped pattern after 30 min; (3) in situ ECSTM reveals a black hole in every ellipsoidal sphere for inactivated HRP in strong alkali solution. The cyclic voltammetry results indicate that the absorbed native HRP can directly catalyse the reduction of hydrogen peroxide, demonstrating that a direct electron transfer reduction occurred between the enzyme and HOPG electrode, whereas the corresponding cyclic voltammograms for denatured HRP and inactivated HRP adsorbed on HOPG electrodes indicate a lack of ability to catalyse H₂O₂ reduction, which confirms that the HRP molecules lost their biological activity. Obviously, electrochemical results powerfully support in situ STM observations.     

Local surface patterning by chitosan-stabilized gold nanoparticles using the direct mode of scanning electrochemical microscopy (SECM)

An approach for patterning surfaces with prepared nanoparticles is described. Chitosan-stabilized gold nanoparticles (Au/chitosan NPs) were locally deposited on stainless steel (StSt), indium tin oxide (ITO), and highly-ordered pyrolytic graphite (HOPG). Deposition was driven by local pH gradient formed between a surface and a scanning electrochemical microscopy tip set in the direct mode. The pH at the substrate was increased upon biasing the surface by negative potentials, which caused the reduction of water. As the pH on the surface exceeded that of $ {\mathrm{pK}}_{{\mathrm{chitosanH}}^{+}}\sim 6.3 $ deprotonation of the amino groups of chitosan caused the irreversible deposition of the chitosan/AuNPs. The effect of different parameters, such as tip–surface distance and time, on deposition was studied. While the potential duration showed no clear influence, smaller tip–substrate distance and more negative potentials applied to the surface caused larger deposits. The overpotential needed for the deposition of nanoparticles on HOPG was the highest while that for StSt was the lowest. On the former, the sluggish kinetics caused the deposition of ring-shaped structures while disk-shaped deposits were formed on the other surfaces.     

Some Unusual Features of Highly Oriented Pyrolytic Graphite Observed by Electrochemical Scanning Tunneling Microscopy

HOPGisoneofthemostcommonlyusedsubstratesinSTMforitiseasilycleavedtoalargeatondcallyflatareaonthebasalplane.ExceptforO.246nmperiodicityrelatedregularatomicstructure,thedefectsandothervarious5e,t,,,,nativetothebasa1planeofHOPGcancoverasmuchasl-lO%ofthesurface.'Ofthesefeatures,stepsarethe'mostconunonlyobserved.'ThewidespreaduseofthissubstratehasledtothediscoveryofsomecrystalimperfectionsnativetothebasalplaneofHOPG',includingstackingfaults,graphitestrandsandfibers,brokenorflakedIayersandsup…     

Electrodeposition of platinum on highly oriented pyrolytic graphite. Part I: electrochemical characterization

The electrochemical deposition of Pt on highly oriented pyrolytic graphite (HOPG) from H2PtCl6 solutions was investigated by cyclic voltammetry and chronoamperometry. The effects of deposition overpotential, H2PtCl6 concentration, supporting electrolyte, and anion additions on the deposition process were evaluated. Addition of chloride inhibits Pt deposition due to adsorption on the substrate and blocking of reduction sites, while SO4(2-) and ClO4- slightly promote Pt reduction. By comparing potentiostatic current-time transients with the Scharifker-Hills model, a transition from progressive to instantaneous nucleation was observed when increasing the deposition overpotential. Following addition of chloride anions the fit of experimental transients with the instantaneous nucleation mode improves, while the addition of SO4(2-) induces only small changes. Chloride anions strongly inhibit the reduction process, which is shifted in the cathodic direction. The above results indicate that the most appropriate conditions for growing Pt nanoparticles on HOPG with narrow size distribution are to use an H2PtCl6 solution with HCl as supporting electrolyte and to apply a high cathodic overpotential.     

Atomic structures and dynamics of a Cu(100) electrode in dilute hydrobromic acid: An in situ STM study

The surface electrochemistry of Cu(100) in 10 mM hydrobromic acid electrolyte has been studied by means of cyclic voltammetry and in situ STM. In the potential range between the onset of the anodic copper dissolution at positive and the hydrogen evolution at negative electrode potentials, the CV of Cu(100) in 10 mM HBr is characterized only by the double-layer charge. Within this potential regime a highly ordered (√2×√2)R45°-superstructure is seen in the STM experiments assigned to specifically adsorbed bromide anions. No desorption of the bromide adlayer has been found in these STM experiments even at extremely negative potentials at the onset of hydrogen evolution. Therefore the bromide desorption potential is concluded to lie within the potential regime of massive hydrogen evolution at even more negative potentials. Adsorbed bromide induces a drastic restructuring and faceting of the surface topography depending on the applied potential. The driving force of this process is the formation of thermodynamically favored copper steps aligned parallel to close packed 100 directions of the bromide adsorbate. Dynamic processes like copper dissolution and deposition are also strongly influenced by the geometry of the (√2×√2)R45° bromide adlayer. Corrosion as well as deposition of copper material follows the close packed 100 directions of the bromide adsorbate. For moderate reaction rates an additional anisotropy between the [001]- and [010]-direction is observed due to the nonequivalence of two different kinds of bromide stabilized copper steps. The origin of these two kinds of steps is the phase relation of close packed adsorbate rows of adjacent terraces. The deposition of copper material does not only start at the lower but unusually, also at the upper sites of step edges leading to the formation of microfacets. Not only the growth of monoatomically high islands is observed but also a double-layer and multilayer growth of copper.     

Growth of palladium nanoparticles on nanostructured highly ordered pyrolytic graphite

We report on the growth of palladium nanoparticles on the basal plane of as‐cleaved highly oriented pyrolytic graphite (HOPG) samples, and on CO₂ ion sputtered nanostructured HOPG surfaces. The morphology of Pd nanostructures grown at room temperature is investigated by scanning tunneling microscopy (STM). The STM observations indicate that the morphology of the Pd films is strongly dependent on the HOPG surface. Stabilized Pd particles only form on the sputtered surface, while ramified Pd particles decorate the clean HOPG terraces. The prestructuring of HOPG surface leads to a selective location of particles at the rim of the nanopits generated by the CO₂ ion sputtering and annealing of the surface. The correlation between size, form, density, spatial distribution of the Pd nanoparticles and the quantity of metal added on surface is discussed. We also describe trench channeling of graphite or graphene basal planes by means of Pd nanoparticles in an ambient environment. Copyright © 2014 John Wiley & Sons, Ltd.     

Decorated Ru/Au(111) and Os/Au(111) surfaces: An in situ STM and electrochemistry study

The structure and reactivity of bimetallic electrodes obtained by spontaneous deposition of Ru and Os on Au(111) single-crystal surfaces are studied. In situ electrochemical STM and cyclic voltammetry are used to characterize a wide range of surface morphologies thus produced. The STM results on Ru/Au(111) demonstrate a pronounced step decoration, while a random distribution of Ru nuclei, quite uniform in size, occurs on terraces. Osmium deposits show a slight preference for deposition on steps, but it also occurs readily on terraces. However, many of the Os islands grow into multilayer heights. The coverage of the Au(111) by the deposited Ru or Os islands for a particular solution concentration depends on the deposition time. Nanostructures of Ru and Os are tested for catalytic behavior and correlated to CO oxidation activity as measured by CO stripping voltammetry. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 11, pp. 1385–1392. Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22, 2005, Moscow. The text was submitted by the authors in English.     

Multiscale imaging and tip-scratch studies reveal insight into the plasma oxidation of graphite

The plasma oxidation process of highly oriented pyrolytic graphite (HOPG) has been investigated through a combination of multiscale (micrometric to atomic) imaging by atomic force and scanning tunneling microscopies (AFM/STM) and STM tip-scratching of the HOPG substrate. Complementary information was obtained by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Repetitive imaging of the same HOPG location following a series of consecutive plasma treatments allowed an accurate determination of the plasma etch rates along both the a and c crystallographic directions of the graphite lattice. The etch rates were typically in the range of a few nm per min along the a axis, and the equivalent of 1-6 graphene layers per min along the c axis. The results pointed to the existence of two main plasma etching regimes, related to short (<20-30 min) and long (> or =30 min) treatment times. This was inferred not only from the measured plasma etch rates but also from the observation of fundamental differences in the atomic-scale surface structure of the plasma-treated HOPG samples, and from the general mechanical behavior of the materials under the action of the AFM tip. In particular, atomic-scale STM imaging suggested a change from a defected, but essentially graphitic, surface in the first regime to an amorphous carbon surface in the second regime. Together with AFM and STM, Raman spectroscopy and XPS provided a consistent picture of the surface structure and chemistry of the plasma-modified HOPG in the two regimes. The implications of these results as well as the possible mechanism that drives the plasma etching process in the two regimes are discussed.     

Ultrafine particles adsorbed on HOPG measured by STM

Small Ag and C particles, about 10 nm in diameter, are produced in gas suspension and precipitated on HOPG substrates for STM analysis. The STM pictures showed much smaller particle concentrations than anticipated from parallel TEM studies. The particles appear very flat in STM, not spherical as expected. These effects could be attributed to the nature of interaction between particle and surface, or to the interaction between tip and particle. Many of our experimental results are consistent with particles moving under the influence of the scanning tip.     

Electrochemical SPM investigation of the solid electrolyte interphase film formed on HOPG electrodes

Solid electrolyte interphase (SEI) film formation on graphite electrodes was studied on highly oriented pyrolytic graphite (HOPG) in nonaqueous electrolyte by in situ electrochemical atomic force microscopy (AFM). For potentials negative to 0.7 V versus Li|Li⁺ a SEI film is formed on the HOPG electrode surface. After the first cycle the film is rough and covers the surface of the HOPG electrode only partially. After the second cycle the HOPG surface is fully covered by a compact film. The thickness of the SEI film was measured by increasing the pressure of the AFM tip and thus scraping a part of the electrode surface. In this way a thickness of about 25 nm was found for the SEI film formed after two scan cycles between 3 and 0.01 V versus Li|Li⁺.