Facet effect on the reconstructed Cu-catalyzed electrochemical hydrogenation of 5-hydroxymethylfurfural(HMF) towards 2,5-bis(hydroxymethy)furan (BHMF)

The electrochemical hydrogenation of HMF to BHMF is an elegant alternative to the conventio nal thermocatalytic route for the production of high-value-added chemicals from biomass resources.In virtue of the wide potential window with promising Faradic efficiency(FE) towards BHMF,Cu-based electrode has been in the center of investigation.However,its structure-activity relationship remains ambiguous and its intrinsic catalytic activity is still unsatisfactory.In this work,we develop a two-step oxidation-reduction strategy to reconstruct the surface atom arrangement of the Cu foam(CF).By combination of multiple quasi-situ/in-situ techniques and density functional theory(DFT) calculation,the critical factor that governs the reaction is demonstrated to be facet effect of the metallic Cu crystal:Cu(110) facet accounts for the most favorable surface with enhanced chemisorption with reactants and selective production of BHMF,while Cu(100) facet might trigger the accumulation of the by-product 5,5'-bis(hydroxy methy)hydrofurion(BHH).With the optimized composition of the facets on the reconstructed Cu(OH)_(2)-ER/CF,the performance could be noticeably enhanced with a BHMF FE of 92.3% and HMF conversion of 98.5% at a potential of -0.15 V versus reversible hydrogen electrode(vs.RHE) in 0.1 M KOH solution.This work sheds light on the incomplete mechanistic puzzle for Cu-catalyzed electrochemical hydrogenation of HMF to BHMF,and provides a theoretical foundation for further precise design of highly efficient catalytic electrodes.

理论指导构建Cu-O-Ti-O_(v)活性位点及其高效电催化还原硝酸根研究

面向国家绿色低碳战略目标,变革化石资源合成氨技术路线变得尤为迫切,开发可再生能源制“绿氨”将成为合成氨领域未来的重要发展方向.将工业废水中的硝酸根(NO_(3)-)电催化还原为氨(NO_(3)RR),既可有效回收氨,又能消除硝酸根污染影响.然而,NO_(3)RR涉及缓慢的八电子转移过程,含有多种反应中间体,其反应机理复杂不明.此外,水系电解液中存在的析氢竞争反应也为高效NO_(3)RR催化剂的开发设计带来了巨大的挑战.为突破高效催化剂的发展瓶颈,本文通过理论模拟,在低成本的催化剂上设计了高效的NO_(3)RR催化活性位点,并利用简单的制备策略合成了目标催化剂.同时,结合原位表征技术,阐明了NO_(3)RR的反应路径及催化机理.本文通过密度泛函理论(DFT)计算发现,Cu/TiO_(2)催化剂上的Cu-O-Ti-O_(v)结构具有较好的NO_(3)-还原活性,该结构不仅能够促进反应中间体NOx-的吸附和活化,还能有效抑制竞争析氢反应,从而降低NO_(3)RR的反应能垒.在该结构上,NO_(3)RR的反应路径为:NO_(3)^(*)→NO_(2)^(*)→HONO^(*)→NO^(*)→*NOH→*N→^(*)NH→*NH2→*NH_(3)→NH_(3).基于理论计算结果,分别采用浸渍法和尿素水解法制备了系列富含Cu-O-Ti-O_(v)结构的Cu/TiO_(2)催化剂.氮气等温吸附-脱附曲线、拉曼光谱(Raman)、电子顺磁共振波谱、X射线光电子能谱(XPS)和傅立叶红外光谱等结果发现,相比于采用浸渍法制备的系列Cu/TiO_(2)催化剂,采用尿素水解法制备的Cu/TiO_(2)(CT-U)催化剂具有更大的比表面积以及更多的Cu-O-Ti-O_(v)位点,说明尿素水解法可提高Cu颗粒在TiO_(2)载体表面的分散度,增强Cu颗粒与TiO_(2)载体之间的相互作用,提高Cu/TiO_(2)催化剂表面的Cu-O-Ti-O_(v)位点含量.将以上制备出的催化剂应用于催化NO_(3)RR中,结果表明,在-1.0 V vs.RHE还原电位下,CT-U催化剂上氨产率可达3046.5μg h^(-1) mgcat^(-1),高于大多数文献报道结果.循环稳定性测试结果表明,在Cu/TiO_(2)催化剂上构建Cu-O-Ti-O_(v)位点还能显著抑制电催化反应过程中Cu物种从Cu/TiO_(2)催化剂上溶出,从而显著增强催化剂的稳定性.此外,设计制备了不含氧空位的Cu/TiO_(2),TiO_(2)-x,Cu,Cu_(2)O以及CuO催化剂,并将其用于催化NO_(3)RR.结果发现,上述催化剂上的氨产率皆明显低于CT-U催化剂,说明Cu,Ti以及O_(v)构成的Cu-O-Ti-O_(v)结构具有较好的催化协同作用,从而显著提升了NO_(3)RR反应活性.最后,通过原位Raman及原位XPS表征检测反应中间体,验证了由DFT模拟出的NO_(3)RR反应路径.综上,通过在Cu/TiO_(2)催化剂上理论指导构建Cu-O-Ti-O_(v)活性位点,实现了NO_(3)RR性能的有效提升.Cu-O-Ti-O_(v)结构中的多位点协同作用不仅促进了NO_(x)-的吸附和活化,而且抑制了电催化过程中Cu物种从催化剂上的溶出,从而提高了催化剂的稳定性.本研究为设计高效稳定的NO_(3)RR催化剂提供了新思路.

TOXIC EFFECTS OF Zn^(2+), Cu^(2+), Cd^(2+)and NH_3 ON CfflNESE PRAWN

This study deals with the toxic effects of Zn2+, Cu2+, Cd2+ and NH3 on Chinese prawn (Penaeus orientalis). The median lethal concentrations of the toxic matters on Chinese prawn were determined. Cd2+】Cu2+】Zn2+】NH3-Nm is the toxic order of these chemicals to Chinese prawn. The toxic order of concentrated Zn2+ and Cd2+ in tissues and organs of Chinese prawn is in the order gill 】 shell + appendage】viscera 】 muscle..

Effect of Cu and Ni on Growth, Mineral Uptake,Photosynthesis and Enzyme Activities of Chlorella vulgaris at Different pH Values

A pH dependent reduction in growth, Pigment, ATP content, O,' evolution, carbonfixation, Photosynthetic electron transport system, nutrient uptake (NO,' and NH4+),nitrate reductase, and ATPase activities and increase in K+ emux of Chlorella vulgaris wasnoticed following supplementation of Cu and Ni to the culture medium. PS II was foundto be more sensitive to both pH and metals than PS I. Though, nitrate reductase (NR) wasmore sensitive to both PH and metals, the ATPase was however, more sensitive t0 metalsbut less sensitive to acidic pH. Acid PH was found to dst the nutrient (NO,' and NH4+)uptake and nitrate reductase in a non-competitive manner. The inhibition Pnduced by thetest metals alone was of noncompetitive type for NO3' uptake, nitrate reductase andATPase and competitive for NH'+ uptake. Acidity not only inhibited the metabolicvariables directly but also through facilitated uptake of metals and increased membranepermeability. A very low sensitivity of ATPase to acidic pH seems to be resgnsible forthe survival of algae in acid environment.

Effect of Current Density on Al Alloy Microplasma Oxidation

The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.

Anisotropic Magnetoresistance Effect in Amorphous and Nanocrystalline Fe(Cu,Nb)-Si-B Alloys

The magnetoresistance effect and magnetic properties in amorphous and nanocrystalline Fe(Cu, Nb)-Si-B ribbons have been investigated, it was observed that the anisotropic magnetoresistance (AMR) of nanocrystalline alloy is much smaller than that of amorphous alloy, Indicating that the anisotropy of nanocrystalline alloy becomes smaller after crystallizing, and the smallest AMR is coincident with the excellent soft magnetic characteristics. It is believed that the smaller magnetic crystalline anisotropy is the origin of the excellent soft magnetic characteristics of nanocrystalline alloy.

Pb, Cu botanogeochemical anomalies and toxic effects on plant cells in Pb-Zn (Sn) ore fields, Northeast Guangxi Autonomous Region, China

In the Lingchuan-Daoping and Xinglu Pb-Zn ore fields in northern and eastern Guangxi Autonomous Region, Pb, Cu botanogeochemical anomalies may be ascribed to the excessive amounts of Pb and Cu taken up by the root system of plants, such as China fir (Cunninghamia lanceolata Lamb. Hook), mason pine (Pinus massoniana Lamb.) and bracken fern (Pteridium aquilinum var. latiusculum). Under transmission electron microscope (TEM), the excess Pb, Cu in the leaf cells of the plants are present as high electron-density substances, which were precipitated in the leaf cells, causing phytotoxic effects by deforming and injuring cellular tissues. The sorts of toxic elements accumulating in the leaf cells are consistent with those of the botanogeochemically anomalous elements in the polluted soil where the plants grow. In addition, the plants may also be capable of resisting the invasion of excess Cu (and Pb) .

Investigation of matrix effects in the MC-ICP-MS induced by Nb, W, and Cu: Isotopic case studies of iron and copper

Some elements normally occur at trace levels while the majority of natural geological materials may be exceedingly enriched in some special cases, such as the Bayan Obo ore deposit where REE and Nb are extremely enriched. These elements may not be removed completely during purification. Therefore, matrix effects will be caused during stable isotope ratio measurement in the MC-ICP-MS. Experiments have shown that the established methods of chromatographic separation of Cu, Fe, and Zn using AG MP-1 Anion Exchange Resin cannot make ef-fective separation of Nb, W, and Cu from Fe using 20 mL 6 M HCl. It is also observed that the elution curves of W and Cu overlap at working conditions and thus W is present in measurable amounts in some sample solutions. Matrix effects in the MC-ICP-MS induced by Nb, W, and Cu during Fe isotope ratio measurements and by W during Cu isotope ratio measurements were thus investigated by examining their changes in delta values between doped and undoped standards. The results show that the effects of the matrix elements Nb, W, or Cu on Fe isotope ratio measurements are minimal in the case of m(Nb)/m(Fe)<0.005, m(W)/m(Fe)<0.01, or m(Cu)/m(Fe)<0.6. This finding, combined with the extremely low levels of W and Cu, and the fact that nearly 90% of Nb can be removed during purification, demonstrates that the methods of chromatographic separation of Fe established before are suitable for Bayan Obo ore samples and that the methods can be simplified when Cu elution is unnecessary. The effects of the matrix element W on Cu isotope determinations are minimal in the case of m(W)/m(Cu)<0.7. Therefore, W exerts no significant effect on the measurements of Cu isotopes for the majority of natural geological materials.

Synergistic effects of bimetallic Cu-Fe/SiO_2 nanocatalysts in selective hydrogenation of diethyl malonate to 1,3-propanediol

Cu-x-Fe-y/SiO2 catalysts were prepared using urea-assisted sol-gel method. The structure and physicochemical properties of the catalysts were characterized using N-2 adsorption-desorption, transmission electron microscopy, H-2-temperature-programmed reduction, powder X-ray diffraction, and X-ray photoelectron spectroscopy. Compared with monometallic Cu or Fe catalysts, the bimetallic Cu-x-Fe-y/SiO2 catalysts exhibited enhanced catalytic performance for the selective hydrogenation of diethyl malonate to 1,3-propanediol. The bimetallic catalyst with an optimal Cu/Fe atomic ratio of 2 exhibited the highest activity, which yielded 96.3% conversion to diethyl malonate and 93.3% selectivity to 1,3-propanediol under the optimal reaction conditions. Characterization results revealed that interactions between Cu and Fe contributed to the improvement of diethyl malonate conversion and selectivity to 1,3-propanediol. The X-ray photoelectron spectroscopy results revealed that the addition of appropriate amount of Fe species enhanced the reduction of Cu2+ species, thereby increasing the Cu-0 species on the surface of bimetallic catalyst. It led to a better chemisorption capacity of hydrogen and further promoted of the activation of hydrogen molecule. The ethyl acetate temperature-programmed desorption results indicated that the FeOx species provided the additional adsorption sites for substrate molecules, and they activated the C=O bond. The improved catalytic performance of bimetallic Cu-x-Fe-y/SiO2 catalyst was mainly attributed to the synergistic effect between Cu-0 and FeOx species. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

单原子Ge助剂修饰Cu(111)晶面上CO_(2)加氢制甲醇的机理研究

针对CO_(2)热催化转化制甲醇过程中CO_(2)吸附、活化较困难及副产物较多的问题,提出采用单原子Ge助剂修饰Cu(111)晶面的解决思路,通过密度泛函理论(DFT)计算研究了CO_(2)在Ge-Cu(111)晶面上加氢合成甲醇的反应机理。结果表明,单原子Ge助剂的电子调控增加了与其相邻的Cu原子的电子云密度,使CO_(2)分子在含Ge活性界面上的吸附能力显著增强:CO_(2)在GeCu(111)晶面上的吸附能约为Cu(111)晶面的1.5倍,约为Pd改性Cu(111)晶面的2.4倍,进而使逆水煤气变换(RWGS)反应路径速控步骤的活化能降低了近20 kJ·moL^(-1),同时衍生出3条生成甲醇的RWGS新路径;此外,Ge-Cu(111)晶面上甲酸盐路径由于速控步骤活化能大幅上升而被禁阻,进而CO及烃类等副产物选择性大幅降低,Ge-Cu(111)晶面上CO_(2)加氢制甲醇选择性升高。

The Weathering Effects of Acidithiobacillus Ferrooxidans to Cu(Ⅱ) Pollution of Fine Grained Copper Mine Tailings

China has accumulated massive fine grained copper mine tailings stocks because of the past mining activities in this area. The tailings contain a variety of heavy metals, and the mass percent of Cu, which is one of the main contaminants in tailings, is up to 0.2601% (analysis by XRF). The Cu can pollute soil and groundwater by rain leaching in the form of Cu(Ⅱ), furthermore ,the fine grained copper-ore-tailings can contaminant larger area by wind for its small granularity ( < 74 μm). The main cause of weathering of mine tailings is due to oxidative dissolution of sulfides. Microorganisms, such as Acidithiobacillus ferrooxidans, play an important role in weathering. These bacteria attach to exposed to mineral surfaces by excreting extracellular polymers and oxidize the sulfide mineral. Some of these bacteria also oxidize Fe2+ to Fe3+ which can chemically oxidize sulfide minerals. These reactions produce voluminous quantities of acid mine drainage and heavy metals which are harmful to the environment and human healthy. This study aims at finding the weathering effects of A. ferrooxidans to Cu(II) pollution of fine grained copper mine tailings, and our experiment applied indigenous A. ferrooxidans FJ-01 to leach the tailings. The optimum test parameters were obtained using shaking flask experiment and SEM observation under the following experimental conditions: 39 days residence time, pulp density 1%-15% (1%, 5% and 15%), 30℃, 120 rpm, pH between 1-3 and redox potential between 400-650 mV. The test results show that the leaching rate of Cu reached 43.1% when the pulp density was 1% after 33 days and kept invariant till the end of the test. In addition, the leaching rate of Cu will decrease as the increase of pulp density, and the maximum rate of 15% pulp density was only 12.5%. From the SEM, it can be seen that the fine grain of tailings flocculated to conglobation under the action of bacterial leaching.

Methods for obtaining two way memory effect and stressed two way memory effect of CuAlNi single crystals

Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction of β phase. The training method of cooling with load can induce a lot of martensite prone to stabilize, thus cause large residual deformation, wide hysteresis and small TWME. Training with constant load can produce STWME larger than 8% with the least residual deformation. By training procedure of martensite reorientation below M f followed by thermal cycling, the TWME is relatively large with very small residual deformation and with comparatively narrow hysteresis of two way memory. The obtained two way memory curve after such training is not a closed loop, and the obtained TWME is not stable. However, these can be improved by thermal cycling. Training with martensite reorientation below M f and thermal cycling under relatively low constant stress throughout the whole training procedure is the optimum way of obtaining TWME, and more than 1.7% TWME can be obtained. The thermomechanical history of the sample has a pronounced effect on the training result. Thermomechanical cycling has a softening effect on martensite. [

MICROSTRUCTURE AND REVERSE SHAPE MEMORY EFFECT IN A Cu-Zn-Al ALLOY

The bainite structure in a Cu-Zn-A1 alloy related to the reverse shape memory effect has been observed by means of TEM.The reverse memory effect may be improved by up to one order of magnitude under applied constraint stress.The widespread propagation of bainite was confirmed to be the diffusion controlled shear process by the parabolic configuration of side interface of bainite plate and the twisting of intersected bainite plates.

HALL EFFECT IN NIOBIUM DOPED YBa_2Cu_3O_(7-y) SUPERCONDUCTOR

YBa_2Cu_(3-x)Nb_xO_(7-y) superconductors have been prepared. XRD shows that the system remains orthorhombic for all composition. Substitution of Nb^(5+) for Cu^(2+) occurs in the Cu(2) sites. The introduction of the Nb^(5+) ions produces some extra free-electrons. These electrons recombine with the carriers of the system. It makes the mobility and the Hall number of YBa_2Cu_(3-x)Nb_xO_(7-y) decrease and also result in a depression in Tc.

Giant Magnetoresistance Effect of [bcc-Fe(M)/Cu](M=Co,Ni) Multilayers

GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3～1.4 nm Cu layer thickness in [Fe(Co)/CuJ, and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by anneahng into account.

Solid Solution Sm_(1+x)Ba_(2-x)Cu_3O_y and Effect of Quench Temperature on SmBa_2Cu_3O_y

By X-ray powder diffraction technique and oxygen content analysis, a solid solution Sm1+xBa2-xCu3Oy has been determined in the range 0≤x≤0.4. When x<0.25. the Sm1+xBa2-xCu3Oy presents orthorhombic symmetry, and the orthorhombic-tetragonaJ transition ocCurs at x = 0.25. With the increase of x, TC decreases and finally breaks. The correlation between ox ygen content and phase structure at different quench temperatures related to Sm Ba2Cu3Oy has been investigated as well

Comparison of the Thermomagnetic and Thermal Effects duringNanocrystallization of Amorphous Fe_(76.5-x)Cu_1Nb_xSi_(13.5)B_9 Alloys

The results of thermomagnetic (TM) and calorimetric (DSC) measurements have been compared in order to clarify some details of the mechanism of nanophase-formation from Finemet-type precursors with different Nb contents. It was found that the main features of the DSC thermograms (shape, relative separation and amplitude of the exothermic peaks characteristic for the precipitation of the Fe-(Si) solid solution and the transition metal borides) depend mainly on the composition of the precursor glass, and are only slightly affected by the heating rate between 20 and 80 K/min. The amplitude of the uprise of the magnetization in the TM curves (attributed to the precipitation of bcc-Fe(Si) and borides) decreases with increasing Nb-content. The Curietemperature of the precursor glasses. Tc(am1), the remainder amorphous phases, Tc(am2) and the bcc nanophase, Tc(n-Fe) are determined from the thermomagnetic curves. The shape of the TM curves is interpreted on the basis of the reactions describing the crystalIization of the hypo-eutectic Fe-B glasses.

Composition Dependence and Irradation Effects on Residual Resistivity in Cu-Al Alloys

Residual electrical resistivity due to short-range order has been calculated for Cu100-xAlx (x=9.13,13.56, 14.5 and 14.76 in at pct) alloys using pseudopotential approach, and the results have been discussed in the light of experimental studies of the local-order structure of these alloys. In case of Cu85.5Al14.5, change in the total residual electrical resistivity due to neutron-irradiation effects has been estimated by including contributions from the short-range order and static atomic displacement correction. Our results show a decrease in the residual resistivity in the irradiated Cu-Al solid solution as compared to the unirradiated sample. This is in accordance with the experimental results

Effect of Microstructure and Sulfide on Corrosion of Cu-Ni Alloys in Seawater

The microstructure and the corrosion product films have been investigated on Cu-Ni alloys by TEM, SEM, AES and electrochemical technique as well as natural seawater exposure tests. Experimental results showed that the alloys had two kinds of microstructure, i.e. recrystallizatjon and incomplete recrystallization. In synthetic seawater containing 2x10^-6 S^2-, the stability of the alloy increased with the increase of deformation and annealing temperature, i.e., the degree of recrystallization. After exposure to natural seawater for different periods of time, the corrosion product films of the recrystallized alloy were rich in Ni and compact, and there were cracks in the outer layer which contained a small amount of S; the films of the alloy of incomplete recrystallization became thick, loose and porous, and obviously of layered structure, and the intergranular corrosion took place in the underlying substrate Besides, a great amount of seawater substance existed in the outer layer and some sulfur was found within the grain boundaries that prefer to corrode. The accelerating effect of sulfides in corrosion of Cu-Ni alloys in seawater is attributed to the coexistence and absorption of sulfides and carbides promoting the preference of corrosion where they absorb, and the formation of dissolvable Cu2S results in keeping the surface of the alloys in the active state.

A Modified Lattice Model of the Reversible Effect of Axial Strain on the Critical Current of Polycrystalline REBa2Cu3O7-δ Films

The strain effect on the critical current is one of the most important properties for polycrystalline YBa2 Cu3O7-δ （REBCO, RE： rare earth） films, in which the reversible effect is intrinsic in the range of strain 0 and the irreversible strain εirr. By introducing the applied strain, a modified grain boundaries （GBs） in the REBCO film is developed. lattice model combining the strain and misorientation of A good agreement of the calculation on the lattice model with the experimental data shows that the lattice model is able to well describe the reversible effect of axial strain on the critical current of the REBCO film, and provides a good understanding of the mechanism of the reversible effect of the strain. Moreover, the effects of the crystallographic texture of the REBCO film and the residual strain εr on the variation of the critical current with the applied strain are extensively investigated. Furthermore by using the developed lattice model, the irreversible strain εirr of the REBCO film can be theoretically determined by comparing the calculation of the critical current-strain curve with the experimental data.