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.

Facile Synthesis as well as Structural, Raman, Dielectric and Antibacterial Characteristics of Cu Doped ZnO Nanoparticles

Here, undoped and Cu doped ZnO nanoparticles(NPs) have been prepared by chemical co-precipitation technique. X-ray diffraction(XRD) results reveal that Cu ions are successfully doped into ZnO matrix without altering its wurtzite phase. The single wurtzite phase of ZnO is retained even for 10 wt% Cu doped ZnO sample. It is observed from the electron microscopy results that higher level of Cu doping varies the morphology of ZnO NPs from spherical to flat NPs. Moreover, the particle size is found to increase with the increase in Cu doping level. Raman spectroscopy results further confirm that Cu dopant has not altered the wurtzite structure of ZnO. Impedance spectroscopy results reveal that the dielectric constant and dielectric loss have increasing trend with Cu doping. Cu doping has been found to slightly decrease the bactericidal potency of ZnO nanoparticles.

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.

Diffusion Behavior of Cumulative He Doped in Cu/W Multilayer Nanofilms at Room Temperature

Cu/W multilayer nanofilms are prepared in pure Ar and He/At mixing atmosphere by the rf magnetron sputtering method. The cross-sectional morphology and the defect distribution of the Cu/W multilayer nanofilms are characterized by scanning electron microscopy and Doppler broadening positron annihilation spectroscopy. The results show that plenty of point defects can be produced by introducing He during the growth of the multilayer nanofilms. With the increasing natural storage time, He located in the near surface of the Cu//W multilayer nanofilm at room temperature could be released gradually and induce the segregation of He-related defects due to the diffusion of He and defects. However, more He in the deep region spread along the interface of the Cu/W multilayer nanofilm. Meanwhile, the layer interfaces can still maintain their stability.

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.

Geometrical Structures and Electronic Properties of Copper-Doped Aluminum Clusters

Using density function theory （DFT）, the Cu-doped Aln （n=1-15） clusters have been stud- ied. The electron affinity, ionization potential, Mulliken population analysis of Cu, mean polarizability, polarizability anisotropy, dipole moments and HOMO-LUMO gaps have also been calculated on the basis of optimized geometries. The results indicate that there is magic numbers in copper-doped aluminum clusters and electronic characteristic depended on the size of clusters. As n=13, the electron affinity and ionization potential of cluster changed more than 0.3 and 0.6 eV respectively, compared with neighborhood clusters.

Microstructure evolution of copper doped beryllium thin films

Copper （Cu） doped beryllium （Be） thin films were deposited on silicon substrates by using a simple ion beam sputtering method, which can also realize the varying of Cu doping concentration. Detailed morphological and structural characterizations of the samples clearly disclose a microstructure evolution of films upon doping Cu. Doping Cu can effectively suppress film grain growth, causing a small grain size as well as uniform size distribution. Furthermore, doping Cu affects the crystallographic texture of film, which leads to the formation of more compact film structure. In particular, the surface smoothness of the doped films is significantly improved, which makes them promising candidates for various applications.

Influence of Cu doping in Magnesium Hydroxide Nanoparticles for Bandgap Engineering

Cu doped Mg(OH)_(2) nanoparticles were synthesized with varying concentrations from 0 to 10%by a chemical synthesis technique of coprecipitation.X-rays diffraction (XRD) of the samples confirms that all the samples acquire the hexagonal crystal structure.XRD results indicated the solubility limit of dopant in the host material and the secondary phase of CuO was observed beyond 3%Cu doping in Mg(OH)_(2).The reduction in the size of nanoparticles was observed from 166 to 103 nm for Mg(OH)_(2) and 10% Cu doped Mg(OH)_(2)samples,respectively.The shift in absorption spectra exhibited the systematical enhancement in optical bandgap from 5.25 to 6.085 eV.A good correlation was observed between the bandgap energy and crystallite size of the nanocrystals which confirmed the size induced effect in the nanoparticles.The transformation in the sample morphology was observed from irregular spherical particles to sepals like shapes with increasing the Cu concentration in the host material.The energy dispersive X-Ray (EDX) analysis confirmed the purity of mass percentage composition of the elements present in the samples.

CO Catalytic Oxide over Cu Atom Supported on Graphene Oxides from the First Principles

Via the first principles calculations, we predict that Cu doped graphene oxide （GO） is a much better nanocatalyst in terms of activity and feasibility. The high activity of Cu doped graphene oxides may be attributed to the charge transfer between the GO and Cu atom, resulting in an activated Cu atom. In the ER mechanism, the CO molecules directly react with the activated O2, then forming a metastable carbonate-like intermediate state （OOCO）. The reaction may proceed via two reaction paths of OOCO → CO2 ＋ O and CO ＋ OOCO → 2CO2, respectively. The calculated results show that the latter path is relatively more thermodynamically favorable with a modest energy barrier, so it should be more preferred. We expect our theoretical predictions to open a new avenue to fabricate carbon-based catalysts for CO oxidation with lower cost and higher activity.

A High-Temperature β-Phase NaMnO2 Stabilized by Cu Doping and Its Na Storage Properties

The high-temperature β-phase NaMnO2 is a promising material for Na-ion batteries（NIBs） due to its high capacity and abundant resources. However, the synthesis of phase-pure -NaMnO2 is burdensome and costineffective because it needs to be sintered under oxygen atmosphere at high temperature and followed by a quenching procedure. Here we first report that the pure β phase can be stabilized by Cu-doping and easily synthesized by replacing a proportion of Mn with Cu via a simplified process including sintering in air and cooling to room temperature naturally. Based on the first-principle calculations, the band gap decreases from 0.7 eV to 0.3 eV, which indicates that the electronic conductivity can be improved by Cu-doping. The designed -NaCu（0.1）Mn（0.9）O2 is applied as cathode in NIBs, exhibiting an energy density of 419 Wh/kg and better performance in terms of rate capability and cycling stability than those in the undoped case.

Giant Low-Field Magnetoresistance in Polycrystalline La_(2/3)Ca_(1/3)Mn_(1-x)Cu_x O_3 Sintered at 1100 ℃

The La_(2/3)Ca_(1/3)Mn_(1- x )Cu_ x O_3 (0≤ x <6%) samples were prepared by sol-gel method. Transport properties, conductive mechanism and low-field magnetoresistance ( MR _0) were investigated. It is found that conductive mechanism is described by Mott′s variable-range hopping and the MR _0 near the insulator-metal transition temperature ( T _p) increases from 2% to 80% with x from 0 to 4% for a low field of 0.3 T. The experiment also shows that the intergrain magnetoresistance is largely improved. The results indicate that a proper amount of Cu doping can substantially improve magnetoresistance effects.

Copper‐doped nickel oxyhydroxide for efficient electrocatalytic ethanol oxidation

Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.

Electronic Transport Properties of La_(2/3)Ca_(1/3)Mn_(0.98)Cu_(0.02)O_3 Sintered at Different Temperature

The sol-gel method was adopted to prepare series of La2/3Cal/3Mn0.98Cu0.02O3 samples sintered at different temperatures, and the structure of samples, high-temperature electrical conductive mechanism and electronic transport properties of double-peak resistance were investigated. X-ray diffraction pattern indicates that the samples are in perovskite structures and obey the Vari- able-Rang Hopping Mechanism of p = p 0exp[（T0/T）^1/4] under high temperatures during the electrical conduction. In addition, based on the polycrystalline granular system surface and image, the reasonable explanation was given for the double-peak resistance phemomenon.

Engineering of electronic and optical properties of ZnO thin films via Cu doping

ZnO thin films doped with different Cu concentrations are fabricated by reactive magnetron sputtering technique. XRD analysis indicates that the crystal quality of the ZnO：Cu film can be enhanced by a moderate level of Cu-doping in the sputtering process. The results of XPS spectra of zinc, oxygen, and copper elements show that Cu-doping has an evident and complicated effect on the chemical state of oxygen, but little effect on those of zinc and copper. Interestingly, further investigation of the optical properties of ZnO：Cu samples shows that the transmittance spectra exhibit both red shift and blue shift with the increase of Cu doping, in contrast to the simple monotonic behavior of the Burstein–Moss effect. Analysis reveals that this is due to the competition between oxygen vacancies and intrinsic and surface states of oxygen in the sample. Our result may suggest an effective way of tuning the bandgap of ZnO samples.

Transport Properties of Polycrystalline La_(2/3)Ca_(1/3)Mn_(1-x)Cu_xO_3 Prepared by Sol-Gel

The influence of Cu dopant (x) and sintering temperature (T s) on the transport properties of La 2/3Ca 1/3Mn 1-xCu xO 3 series samples prepared by Sol-Gel technique was investigated.X-ray diffraction patterns show that all the samples with different Cu dopant and sintering temperatures (T s) are of single phase without obvious lattice distortion.Experimental results indicate that the insulator-metal transition temperature is directly related to the sintering temperature and Cu dopant x.It is interesting to observe that a proper amount of Cu dopant can substantially improve magnetoresistance effects.

Effect of Cu/Zn Substitution in MgO Nanostructures for Tuning the Optical Bandgap and Structural Properties

Low cost co-precipitation method was used to synthesize Cu(0-0.05)doped MgO samples with fixed concertation of Zn=0.01.X-ray diffraction(XRD)spectra confirmed the phase purity of the samples for 0≤Cu≤0.03 doping concentration.The secondary phase for 0.04≤Cu≤0.05 exhibited the formation of mixed metal oxides.The crystallite size was found to increase from 17.5 to 23.5 nm for 0≤Cu≤0.03 and then decreased from 22 to 18.5 nm for 0.04≤Cu≤0.05.The estimated bandgap first reduced from 5.48 to 4.88 eV and then increased from 5.21 to 5.36 eV.The morphology of the samples transformed from spheroidal shape to star-like shape.The obtained results reveal that the structural and optical property are in good agreement with the morphological transition.The peak shifting towards the lower values of vibrational frequency from 694 to 579 cm^(-1) confirms the incorporation of Cu/Zn in Mg-O lattice.The tuning of optical bandgap and structural properties with varying dopant concentration in MgO nanomaterials can be used for multifunctional modern energy storage and optoelectronic devices.

Cu-doped Bi/Bi_(2)WO_(6) catalysts for efficient N_(2) fixation by photocatalysis

In this paper,Cu-doped Bi_(2)WO_(6)was synthesized via a solvothermal method and applied it in photocatalytic N_(2)immobilization.Characterization results showed the presence of a small amount of metallic Bi in the photocatalyst,indicating that the synthesized photocatalyst is actually Bi/Cu-Bi_(2)WO_(6)composite.The doped Cu had a valence state of+2 and most likely substituted the position of Bi^(3+).The introduced Cu did not affect the metallic Bi content,but mainly influenced the energy band structure of Bi_(2)WO_(6).The band gap was slightly narrowed,the conduction band was elevated,and the work function was reduced.The reduced work function improved the transfer and separation of charge carriers,which mainly caused the increased photoactivity.The optimized NH_(3)generation rates of Bi/Cu-Bi_(2)WO_(6)reached 624 and 243μmol·L^(-1)·g^(-1)·h^(-1)under simulated solar and visible light,and these values were approximately 2.8 and 5.9 times higher those of Bi/Bi_(2)WO_(6),respectively.This research provides a method for improving the photocatalytic N_(2)fixation and may provide more information on the design and preparation of heteroatom-doped semiconductor photocatalysts for N_(2)-to-NH_(3)conversion.

Structural, Optical and Electrical Properties of Ga Doped ZnO/Cu grid/Ga Doped ZnO Transparent Electrodes

Ga doped ZnO （OZO）/Cu grid/GZO transparent conductive electrode （TCE） structures were fabricated at room temperature （RT） by using electron beam evaporation （EBE） for the Cu grids and RF magnetron sputtering for the GZO layers. In this work, we investigated the electrical and optical characteristics of GZO/Cu grid/GZO multilayer electrode for thin film solar cells by using evaporated Cu grid and sputtered GZO thin films to enhance the optical transparency without significantly affecting their conductivity. The optical transmittance and sheet resistance of GZO/Cu grid/GZO multilayer are higher than those of GZO/Cu film/GZO multilayer independent of Cu grid separation distance and increase with increasing Cu grid separation distances. The calculation of both transmittance and sheet resistance of GZO/Cu grid] GZO multilayer was based on Cu filling factor correlated with the geometry of Cu grid. The calculated values for the transmittance and sheet resistance of the GZO/Cu grid/GZO multilayer were similar to the experimentally observed ones. The highest figure of merit ФTc is 5.18× 10^-3Ω^-1 for the GZO/Cu grid] GZO multilayer with Cu grid separation distance of 1 mm was obtained, in this case, the transmittance and resistivity were 82.72% and 2.17 × 10 ^-4Ωcm, respectively. The transmittance and resistivity are accentahle for nractical thin film snlar cell annlicatinn~

Preparation of In2S3 and Cu-Doped In2S3 2D Ultrathin Nanoflakes with Tunable Absorption and Intense Photocurrent Response

We reported an effective method to synthesize In2S3 and Cu-doped In2S3 two-dimensional ultrathin nanoflakes by the hydrothermal method through tuning the Cu/In molar ratio. The transmission electron microscope images showed that the products had ultrathin flake-like shape with wrinkling and rolling. The X-ray diffraction patterns indicated the crystal phase of nanoflakes was varied from β-In2S3 to tetragonal-Cu InS2 as the Cu/In molar ratio was increased. The In2S3 nanoflakes exhibited absorption band at 450 nm, while new absorption peaks in turn appeared at 550 nm and 670 nm as the Cu/In molar ratio was increased. In addition, the two-dimensional ultrathin nanoflakes exhibited intense photocurrent response.

Reactive DC Magnetron Sputter Deposited Titanium-Copper-Nitrogen Nano-Composite Thin Films with an Argon/Nitrogen Gas Mixture

A sintered Ti13Cus7 target was sputtered by reactive direct current （DC） magnetron sputtering with a gas mixture of argon/nitrogen for different sputtering powers. Titanium-coppernitrogen thin films were deposited on Si （111）, glass slide and potassium bromide （KBr） substrates. Phase analysis and structural properties of titanium-copper-nitrogen thin films were studied by X-ray diffraction （XRD）. The chemical bonding was characterized by Fourier transform infrared （FTIR） spectroscopy. The results from XRD show that the observed phases are nano-crystallite cubic anti rhenium oxide （anti ReO3） structures of titanium doped Cu3N （Ti：Cu3N） and nanocrystallite face centered cubic （fcc） structures of copper. Scanning electron microscopy and energy dispersive X-ray spectroscopy （SEM/EDX） were used to determine the film morphology and atomic titanium/copper ratio, respectively. The films possess continuous and agglomerated structure with an atomic titanium/copper ratio （-0.07） below that of the original target （- 0.15）. The transmittance spectra of the composite films were measured in the range of 360 nm to 1100 nm. Film thickness, refractive index and extinction coefficient were extracted from the measured transmittance using a reverse engineering method. In the visible range, the higher absorption coefficient of the films prepared at lower sputtering power indicates more nitrification in comparison to those prepared at higher sputtering power. This is consistent with the formation of larger Ti：Cu3N crystallites at lower sputtering power. The deposition rate vs. sputtering power shows an abrupt transition from metallic mode to poisoned mode. A complicated behavior of the films＇ resistivity upon sputtering power is shown.