Cu,N codoped carbon nanosheets encapsulating ultrasmall Cu nanoparticles for enhancing selective 1,2-propanediol oxidation

In the selective oxidation of biomass-based 1,2-propanediol(PDO)with oxygen as the terminal oxidant,it is challenging to improve the lactic acid(LA)selectivity for nonnoble metal nanoparticles(NPs)due to their limited oxygen reduction rate and easy C-C cleavage.Given the high economic feasibility of nonnoble metals,i.e.,Cu,in this work,copper and nitrogen codoped porous carbon nanosheets encapsulating ultrafine Cu nanoparticles(Cu@Cu-N-C)were developed to realize highly selective of PDO oxidation to LA.The carbon-encapsulated ultrasmall Cu^(0)NPs in Cu@Cu-N-C have high PDO dehydrogenation activity while N-coordinated Cu(Cu-N)sites are responsible for the high oxygen reduction efficacy.Therefore,the performance of catalytic PDO conversion to LA is optimized by a proposed pathway of PDO→hydroxylacetone→lactaldehyde→LA.Specifically,the enhanced LA selectivity is 88.5%,and the PDO conversion is up to 75.1%in an O_(2)-pressurized reaction system(1.0 MPa O_(2)),superior to other Cu-based catalysts,while in a milder nonpressurized system(O_(2)flow rate of 100 mL min-1),a remarkable LA selectivity(94.2%)is obtained with 39.8%PDO conversion,2.2 times higher than that of supported Au nanoparticles(1%Au/C).Moreover,carbon encapsulation offers Cu@Cu-N-C with strong leaching resistance for better recycling.

Oxygen vacancy defects engineering on Cu-doped Co_(3)O_(4) for promoting effective COS hydrolysis

The activation of H_(2)O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co_(3)O_(4) to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H_(2)O are adsorbed and activated by oxygen vacancy.The 10 at%Cu doped Co_(3)O_(4) sample(10Cu-Co_(3)O_(4))exhibits the optimal activity,100%of COS conversion at 70℃.The improved oxygen vacancies of CueCo_(3)O_(4) accelerate the activation of H_(2)O to form active -OH.COS binds with hydroxyl to form the intermediate HSCO^(-)_(2),and then the activated-OH on the oxygen vacancy reacts with HSCO^(-)_(2) to form HCO^(-)_(3).Meanwhile,the catalyst exhibits high catalytic stability because copper species(Cu+/Cu^(2+))redox cycle mitigate the sulfation of Co_(3)O_(4)(Co^(2+)/Co^(3+)).Our work offers a promising approach for the rational design of cobalt-related catalysts in the highly efficient hydrolysis COS process.

3-羟基丙酸甲酯加氢合成1,3-丙二醇反应中La对Cu/SiO_(2)催化剂的修饰作用

[目的] 3-羟基丙酸酯加氢制备1,3-丙二醇(1,3-PDO)过程中存在β-羟基脱除等副反应,导致1,3-PDO的选择性和收率不高,其中高效催化剂的开发是解决该问题的关键.[方法]采用蒸氨法制备了不同添加量La修饰的20Cu/SiO_(2)催化剂,对其进行催化性能评价,并通过H_(2)程序升温还原(H_(2)-TPR)、X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和N_(2)物理吸附-脱附对其进行表征.[结果] 20Cu-0.50La/SiO_(2)的催化性能最佳,它显著地提高了3-羟基丙酸甲酯(3-HMP)加氢制1,3-PDO的催化活性和稳定性,其中3-HMP转化率为91.8%,1,3-PDO的选择性和收率分别为85.2%和78.2%.这是在高液时空速(LHSV=0.10 h^(-1))的条件下取得的最佳结果.[结论] La的加入与Cu产生了强相互作用,增强了催化剂中Cu的分散性,同时提高了Cu^(+)物种表面浓度,使活性Cu的比表面积增加,从而提高了加氢反应的活性和稳定性.

Cu核微焊点液-固界面反应及剪切行为研究

相较于传统Sn基焊点,Cu核焊点具备更好的导热性、导电性及力学性能。为揭示尺寸效应对Cu核焊点界面反应及剪切强度的影响,制备了不同Sn镀层厚度的Cu核焊点(Cu@Ni-Sn/Cu)。观察回流不同时间后Cu核微焊点横截面微观组织,研究了Cu核微焊点在尺寸效应下的液-固界面反应。之后对Cu核微焊点进行剪切测试,结合断口形貌,分析断裂机理。界面反应结果表明:Cu@Ni-Sn/Cu焊点在250℃回流时,Sn/Ni界面生成Ni含量较高的针状(Cu,Ni)_(6)Sn_(5)IMC,Sn/Cu界面生成Ni含量较低的层状(Cu,Ni)_(6)Sn_(5)IMC。剪切测试结果表明:随着Sn镀层厚度增加,Cu@Ni-Sn/Cu焊点的剪切强度先增大后减小。基于Sn镀层厚度对界面(Cu,Ni)_(6)Sn_(5)IMC层体积的直接影响,Sn层厚度的增加提升了焊点剪切强度。然而Cu@Ni-Sn(60μm)/Cu焊点中Cu核位置的偏移,造成剪切强度略有降低。

W-Cu复合材料的应用现状及掺杂改性的研究进展

W-Cu复合材料因具有高的硬度、耐磨性、抗烧蚀性能、导电性和导热性以及低热膨胀系数等综合性能而被广泛应用于多种工业领域。本文介绍了W-Cu复合材料的最新研究进展及其在电触头、微电子、军事、功能梯度材料方面的应用现状,着重总结和分析了目前W-Cu复合材料掺杂改性的分类及原理,以及掺杂改性对材料性能的影响,最后提出了W-Cu复合材料未来发展的潜在问题和值得关注的研究方向。

3,5-二氯水杨醛缩-4-氨基安替比林Cu(Ⅱ)和Zn(Ⅱ)配合物的合成、晶体结构及抗肿瘤活性研究

利用3,5-二氯水杨醛与4-氨基安替比林,通过缩合反应,合成3,5-二氯水杨醛缩-4-氨基安替比林希夫碱配体(HL),配体与CuCl_(2)·2H_(2)O、Zn(Ac)_(2)·2H_(2)O,利用溶剂热反应合成两个新型的希夫碱配合物[CuL_(2)](配合物1)和[ZnL_(2)](配合物2)。对合成的配合物进行了红外光谱、热重分析、PXRD表征,用X射线单晶衍射确定了配体(HL)、配合物1和配合物2的分子结构,单晶衍射分析结果表明,配体(HL)晶体属于单斜晶系,空间群为P2_(1)/n,配合物1晶体属于单斜晶系,空间群为C2/c,配合物2晶体属于单斜晶系,空间群为P2_(1)/c,配合物1是四配位的四方形结构,配合物2是扭曲的六配位的八面体结构。MTT法检测了配体(HL)及配合物对3种人体肿瘤细胞株(MDA-MB-231、CNE-2Z、A-549)体外抗肿瘤活性。检测结果显示,配合物对癌细胞的抑制作用明显比配体好,配合物1对MDA-MB-231细胞和CNE-2Z细胞抗增殖活性最好,其IC_(50)值分别为(1.215±0.07)μmol/L、(4.417±0.28)μmol/L均低于顺铂IC_(50)值,配合物2对A-549细胞和MDA-MB-231细胞也表现出较好的抗增殖活性。

Cu/MOF双功能催化剂催化乙酰丙酸制取γ-戊内酯的研究

传统化石能源的日益消耗引发了严重的能源危机和环境污染等问题,亟需开发和利用可再生能源。生物质因其资源丰富、成本低廉和清洁的特点,引起了人们的广泛关注。采用简单、高效的溶剂热方法构筑了一种金属有机框架封装金属Cu的新型复合材料,Cu/MOF-808,该催化剂中Cu原子锚定在Zr基金属有机框架MOF-808次级结构单元的缺陷位。Cu/MOF-808催化剂在较温和的反应条件下(140℃),以异丙醇为氢源,通过催化转移加氢路径,将生物质平台分子乙酰丙酸选择性加氢转化为γ-戊内酯,产率达到91.5%。溶剂影响因素结果表明,Cu/MOF-808催化剂在异丙醇中表现出最好的活性和选择性,远高于甲醇、乙醇和仲丁醇体系,主要得益于异丙醇优异的供氢能力。此外,Cu/MOF-808催化剂具有良好的稳定性和可重复利用性,在5次循环后仍能保持较高的催化活性和目标产物选择性。机理研究揭示了MOF锚定的高分散Cu金属位点和MOF中Zr簇的Lewis酸性位点的高效协同作用,促进了乙酰丙酸高效催化转化。

Structural, Optical and Photocatalytic Properties of Cu2+ Doped ZnO Nanorods with Using HMTA Solvent Prepared by Hydrothermal Method

In this experiment, Cu2+ doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu2+ ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn2+). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn2+:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu2+ doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu2+ doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu2+ doping ratio of 2 mol.%.

Meso-macroporous Fe-doped Cu O: Synthesis, characterization, and structurally enhanced adsorption and visible-light photocatalytic activity

The meso-macroporous Fe-doped Cu O was prepared by a simple hydrothermal method combined with post-annealing. The samples were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), Brunauer-Emmett-Teller N2 adsorption-desorption analyses and UV-vis diffuses reflectance spectroscopy. The Fe-doped Cu O sample shows higher adsorption capacity and photocatalytic activity for xanthate degradation than pure Cu O under visible light irradiation. In addition, the adsorption process is found to fit Langmuir isotherms and pseudo-second-order kinetics. The the first order kinetic Langmuir Hinshelwood model was used to study the reaction kinetics of photocatalytic degradation, and the apparent rate constant( k) was calculated. The value of k for Fe-doped Cu O is 1.5 times that of pure Cu O. The higher photocatalytic activity of Fe-doped Cu O is attributed to higher specific surface area together with stronger visible light absorption.

Electrical breakdown characteristic of a Ce-doped W-Cu contact material

W-Cu composite powder doped with Ce (1.5 wt.%) was prepared by mechanical alloying (MA),and the W-Cu contact material was fabricated by hot pressing sintering in an electrical vacuum furnace.The microstructure,electric conductivity,hardness,and breakdown voltage of the Ce-doped W-Cu alloy were measured and compared with a conventional W-Cu alloy prepared by powder metallurgy.The results show that microstructural refinement and uniformity can improve the breakdown behavior and the electric arc stability of the Ce-doped W-Cu contact material.Also,the Ce-doped W-Cu contact material shows the characteristic of spreading electric arc,which is beneficial to electric arc erosion.

Preparation and photocatalytic activity of Cu^(2+)-doped TiO_2/SiO_2

Cu2+-doped nanostructured TiO2-coated SiO2 (TiO2/SiO2) particles were prepared by the layer-by-layer assembly technique and their photocatalytic property was studied. TiO2 colloids were synthesized by the solgel method using TiOSO4 as a precursor. The experimental results showed that TiO2 nanopowders on the surface of SiO2 particles were well distributed and compact. The amount of TiO2 increased with the increase in coating layers. The shell structure appeared to be composed of anatase titania nanocrystals at 550°C. The 2-layer coated TiO2 particles on the surface showed a higher degradation rate compared with all the different-layer samples. The photocatalytic activity of Cu2+-doped TiO2/SiO2 was higher than that of undoped TiO2/SiO2. The optimum dopant content was about 0.10wt%.

Temperature Effects on Gas Sensing Properties of Electrodeposited Chlorine Doped and Undoped n-Type Cuprous Oxide Thin Films

As one of the most widely used domestic fuels, the detection of possible leakages of Liquefied Petroleum (LP) gas from production plants, from cylinders during their storage, transport and usage is of utmost importance. This article discusses a study of the response of undoped and chlorine doped electrodeposited n-type Cuprous Oxide (Cu2O) films to of LP gas. Undoped n-type Cu2O films were fabricated in an electrolyte bath containing a solution of sodium acetate and cupric acetate whereas n-type chlorine doped Cu2O thin films were prepared by adding a 0.02 M cuprous chloride (CuCl2) into an electrolyte solution containing lactic acid, cupric sulfate and sodium hydroxide. The n-type conductivity of the deposited films was determined using spectral response measurements. The structural and morphological properties of the fabricated films were monitored using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Due to doping, the overall conductivity of the chlorine doped n-type Cu2O films increased by several orders of magnitude. The temperature dependent gas responses of both the undoped and chlorine doped n-type Cu2O thin films to the LP gas was monitored by measuring the electrical resistance (R), and using the contact probe method at a constant gas flow rate of 0.005 ml/s. Upon exposure to gases, both doped and undoped films showed a good response to the gas by increasing/decreasing the electrical resistance by ΔR. The undoped n-type Cu2O thin films showed a negative response (ΔR 2O thin films initially showed a positive response (ΔR > 0) to the LP gas which then reversed its sign to give a negative response which peaked at 52°C. The positive response shown by the chlorine doped Cu2O films vanished completely at 42°C.

Theoretical investigation of lithium ions’ nucleation performance on metal-doped Cu surfaces

Lithium metal batteries(LMBs)of an ultrahigh theoretical energy density have attracted lots of attentions for a wide range of practical applications.However,there are still numerous challenges in LMBs system,such as poor cycling performance,complicated interfacial reactions,low Coulombic efficiency,and uncontrollable lithium dendrites.Understanding Li^+ions’nucleation mechanism is essential to tackle the uncontrolled growth of lithium dendrites.However,the nucleation behavior of Li+ions is interfered by the structural complexities of existing substrates during the reduplicative plating/stripping process and the rational mechanism of uniform nucleation of Li^+ions has not been clearly understood from the theoretical point of view.In our work,first-principles theoretical calculations are carried out to investigate the Li^+ions nucleation performance on metal-doped Cu surfaces(MDCSs)and the key descriptors that determines the properties of various MDCSs are systematically summarized.It is found that the introduction of heterogeneous doping Ag and Zn atoms will induce a gradient adsorption energy on MDCSs,and such gradient deposition sites can reduce the diffusion barriers and accelerate the diffusion rates of Li+ions dynamically.By maneuvering the Li+ions nucleation on MDCSs,a dendrite-free lithium metal anode can be achieved without the use of porous matrixes and complex synthesis process,which can be attributed to suppress the uncontrollable lithium dendrites for realizing the high-efficiency LMBs.

The effects of Zn vacancies on ferromagnetism in Cu-doped ZnO films controlled by oxygen pressure and Li doping

Zn0.99Cu0.01O films were studied experimentally and theoretically.The films were prepared by pulsed-laser deposi tion on Pt(111)/Ti/SiO2/Si substrates under various oxygen pressures to investigate the growth-dependence of the ferromag netic properties.The structural,magnetic,and optical properties were studied,and it was found that all the samples possess a typical wurtzite structure,and that the films exhibit room-temperature ferromagnetism.The sample deposited at 600℃and an oxygen pressure of 10 Pa showed a large saturation magnetization of 0.83μB/Cu.The enhanced ferromagnetism in the(Cu,Li)-codoped ZnO is attributable to the existence of Zn vacancies(VZn),as shown by first-principles calcu lations.The photoluminescence analysis demonstrated the existence of V Zn in both Zn0.99Cu0.01O and(Cu,Li)-codoped ZnO thin films,and this plays an important role in the increase of ferromagnetism,according to the results of first-principles calculations.

Thermal stability and thermoelectric properties of Cd-doped nano-layered Cu2Se prepared using NaCl flux method

Cu2Se is a promising"phonon liquid-electron crystal"thermoelectric material with excellent thermoelectric performance.In this work,Cd-doped Cu2-xSeCdx(x=0,0.0075,0.01,and 0.02)samples were prepared using NaCl flux method.The solubility of Cd in Cu2Se at room temperature was less than 6%,and a second phase of CdSe was found in the samples with large initial Cd content(x=0.01 and 0.02).Field-emission scanning electron microscopic image showed that the arranged lamellae formed a large-scale layered structure with an average thickness of approximately 100 nm.Transmission electron microscopy demonstrated that doping of Cd atoms did not destroy the crystal integrity of Cu2Se.A small amount of Cd in Cu2Se could reduce the electrical and thermal conductivities of the material,thus significantly enhancing its thermoelectric performance.With the increase in Cd content in the sample,the carrier concentration decreased and the mobility increased gradually.Thermogravimetric differential thermal analysis showed that no weight loss occurred below the melting point.Excessive Cd doping led to the emergence of the second phase of CdSe in the sample,thus significantly increasing the thermal conductivity of the material.A maximum ZT value of 1.67 at 700 K was obtained in the Cu1.9925SeCd0.0075 sample.

Effect on Defect in N or F-Doped Ferromagnetic Zn_1-xCu_xO: First-Principles Study

We investigated the electronic and magnetic properties for O or Zn defect of (Cu, N) or (Cu, F)-co- doped ZnO with the concentration of 2.77% - 8.33% by using the first-principles calculations. The ferromagnetic coupling of Cu atoms in (Cu, N)-codoped ZnO can be attributed to the hole-mediated double-exchange through the strong 2p-3d coupling between Cu and neighboring O (or N) atoms. The ferromagnetism in Cu-doped ZnO is controllable by changing the carrier density. The Cu magnetic moment in low Cu concentration (2.77%) is increased by the N-doping, while for the F-doping it decreases. For two Cu atoms of Zn0.9445Cu0.0555O with O vacancy, the antiferromagnetic state is more energetically favorable than the ferromagnetic state.

Spectral features and antibacterial properties of Cu-doped ZnO nanoparticles prepared by sol-gel method

Zn_(1-x)Cu_x O(x=0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%(x = 0.05). However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli(Gram negative bacteria)cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.

Structural,optical,and electrical properties of Cu-doped ZrO_2 films prepared by magnetron co-sputtering

Copper(Cu)-doped ZrO_2(CZO) films with different Cu content(0 at.%～ 8.07 at.%) are successfully deposited on Si(100) substrates by direct current(DC) and radio frequency(RF) magnetron co-sputtering. The influences of Cu content on structural, morphological, optical and electrical properties of CZO films are discussed in detail. The CZO films exhibit ZrO_2 monocline(ˉ111) preferred orientation, which indicates that Cu atoms are doped in ZrO_2 host lattice. The crystallite size estimated form x-ray diffraction(XRD) increases by Cu doping, which accords with the result observed from the scanning electron microscope(SEM). The electrical resistivity decreases from 2.63 ?.cm to 1.48 ?·cm with Cu doping content increasing, which indicates that the conductivity of CZO film is improved. However, the visible light transmittances decrease slightly by Cu doping and the optical band gap values decrease from 4.64 eV to 4.48 eV for CZO films.

Studies of Photorefractive Crystals of Cu-Doped (K_(0.5) Na_(0.5))_(0.2)(Sr_(0.75)Ba_(0.25))_(0.9)Nb_2O_6

In this paper, photorefractive crystals of Cu-doped (K0.5Na0.5)0.2 (Sr0.75Ba0.25)0.9Nb2O6 (KNSBN) are systematically studied. A series of Cu-doped KNSBN crystals have been grown and the samples with Cu-dopant in different levels and thicknesses have been fabricated. Their photorefractive properties including two-wave coupling gain coefficients and response rate are experimentally studied in details. The results show that (1) with high Cudopant cocentration, the crystal has larger coupling gain coefficient, higher effective charge carrier density, and faster time response; (2) thinner sample shows larger coupling gain coefficientl (3) at shorter wavelength 9 the crystal sample shows larger coupling gain coefficient and faster time response. The Cu-doping mechanisms were briefly referred. The analyses of the relationships among the crystal’s two-wave coupling, absorption property and the self-pumped phase conjugation are given. All the results show that Cu-doped KNSBN crystals are a kind of very promising photorefractive materials.