Search

Excited state calculations are performed to predict the electronic structure and optical absorption characteristics of Cu-doped anatase Ti O 2  nanofilms, focusing on their (101) and (001) surface terminations. Using model structures that successfully represent the equilibrium positions of deposited Cu atoms on the Ti O 2  surface, a comprehensive analysis of the absorption spectra for each considered model is made. The proposed modeling reveals phenomena when photogenerated electrons from Ti O 2  tend to accumulate in the vicinity of the deposited Cu atoms exposed to photon energies surpassing the band gap of Ti O 2  (approximately 3.2 eV). The crucial transition states that are essential for the creation of potential photocatalytic materials are identified through detailed calculations of the excited states. These insights hold substantial promise for the strategic design of advanced photocatalytic materials. The obtained results provide a base for subsequent analyses, facilitating the determination of heightened surface reactivity, photostimulated water splitting, and antibacterial properties. [ABSTRACT FROM AUTHOR]

Herein, new efficient photocatalysts composed of Cu doped NiS/ZnS quantum dots-composites were synthesized by coprecipitation technique for treatment of organic dyes. Treatment of dyeing-wastewater is an important issue to reduce the environmental pollution and providing a large quantity of pure water. The transmission electron microscope images of pure and Cu doped NiS/ZnS composites show quantum dots particles with size of 3–4 nm. The X-ray diffraction confirmed the formation of cubic ZnS and rhombohedral NiS. Optically, doping by 4 wt% Cu ions was reduced the band gap energy of ZnS from 3.4 to 2.98 eV, which improve the visible light absorption. 4 wt% Cu doped NiS/ZnS nanocomposite reveals a fast and remarkable photodegradation efficiency of 95%, 98% and 97% towards 20 ppm methyl green, methylene blue and Congo red during 60 min of sunlight irradiation. For three cycles, 4 wt% Cu doped NiS/ZnS nanocomposite exhibits significant photodegradation activities of 98%, 92% and 85%, respectively. The improvements of the photocatalytic activity of Cu doped NiS/ZnS nanocomposite can be attributed to some factors including visible-light absorption and charge carriers separation. The Cu doping improves the visible light response of ZnS through reducing the band gap which reinforce the number of the excited electron-hole pairs. Too, Cu ions act as trapping centers (Cu2+ + e → Cu+) which boost the separation of the excited electron-hole pairs and consequently improve the photodegradation activity. This study point out that the integration of p-n heterostructure and doping strategies are efficient for deign of photocatalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]

This study explores the use of Cu dopant to improve the optoelectronic properties and stability of CsPbX3 perovskites for blue-light-emitting diode material. The addition of Cu causes the metal octahedron of orthorhombic CsPbBr3 to shrink, which relaxes the lattice strain from the distortion and twisting of the [PbX6] octahedron and reduces energy from Jahn–Teller effects. A crystal orbital Hamilton population (COHP) analysis reveals that the Cu-Br bond in the [CuX6] octahedron has a higher integrated projected COHP (IpCOHP), and the strong hybridization between the Cu-3d and Br-4p bond enhances the bond interaction and the whole crystalline lattice. The addition of Cu dopants in CsPbBr3 perovskites results in a stronger framework that suppresses intrinsic defects like Br vacancies, leading to enhanced photoluminescence (PL) performance. Additionally, the Cu-3d orbitals contribute to the valence band and increase the band gap, resulting in a blue shift of the luminescence from Cu-doped CsPbBr3. These findings indicate that Cu dopants significantly improve the luminescence efficiency and the stability of CsPbBr3 perovskites, making them suitable for blue light LED applications. [ABSTRACT FROM AUTHOR]

Excited state calculations are performed to predict the electronic structure and optical absorption characteristics of Cu-doped anatase TiO2 nanofilms, focusing on their (101) and (001) surface terminations. Using model structures that successfully represent the equilibrium positions of deposited Cu atoms on the TiO2 surface, a comprehensive analysis of the absorption spectra for each considered model is made. The proposed modeling reveals phenomena when photogenerated electrons from TiO2 tend to accumulate in the vicinity of the deposited Cu atoms exposed to photon energies surpassing the band gap of TiO2 (approximately 3.2 eV). The crucial transition states that are essential for the creation of potential photocatalytic materials are identified through detailed calculations of the excited states. These insights hold substantial promise for the strategic design of advanced photocatalytic materials. The obtained results provide a base for subsequent analyses, facilitating the determination of heightened surface reactivity, photostimulated water splitting, and antibacterial properties.

The incorporation of Cu dopant into CoNiO/CoNi heterostructure enhances electron transfer from metal atoms to O atom, leading to the accelerated water dissociation and H evolution. The boosted electron exchange and mass transportation deriving from the introduction of Cu NWs and hierarchically peach-flower-shaped nanostructure further reinforce the HER activity of the Cu-CoNiO/CoNi catalyst. [Display omitted] • Copper-restructured cobalt-nickel/cobalt-nickel oxide heterostructure was prepared. • A hierarchically peach-flower-shaped electrocatalyst on copper nanowires was designed. • The boosted electron exchange and mass transportation reinforce the HER activity. • Our findings rank among the topmost when compared to reported catalysts. The slow kinetics of water dissociation on electrocatalysts lacking platinum hinders the advancement of cost-effective hydrogen production via alkaline water electrolysis. Herein, a hierarchically peach-flower-shaped electrocatalyst consisting of copper-restructured cobalt–nickel/cobalt–nickel oxide heterostructure anchored on copper nanowires (Cu-CoNiO/CoNi@Cu NWs) is developed for efficient hydrogen evolution reaction (HER). Benefiting from the optimized electronic configuration and geometric structure, this Cu-CoNiO/CoNi@Cu NWs catalyst performs an outstanding alkaline HER activity of 29 mV at 10 mA cm−2 and 98 mV at 100 mA cm−2, which is comparable with the state-of-the-art Pt/C catalyst (26 mV at 10 mA cm−2 and 117 mV at 100 mA cm−2). Our findings rank among the topmost catalytic efficiencies when compared to all previously reported non-noble metal catalysts and numerous noble metal catalysts. The combined experimental exploration and theoretical studies reveal that the incorporation of Cu dopant into CoNiO/CoNi heterostructure enhances electron transfer from metal atoms to O atom, leading to the formation of the polarized electric field to accelerate water dissociation and H evolution, eventually facilitating the overall alkaline HER process. The boosted electron exchange and mass transportation deriving from the introduction of Cu NWs and hierarchically peach-flower-shaped nanostructure further reinforce the HER activity of the Cu-CoNiO/CoNi catalyst. [ABSTRACT FROM AUTHOR]

The ZnTe thin films are typically employed as back contact interface layer in between CdTe absorber and metal electrode in superstrate device architecture for reducing open circuit voltage loss and enhancing device performance. Copper (Cu) is considered as a vital dopant for catalyzing recrystallization and facilitating inter-diffusion between CdTe and ZnTe layers. Hence, the present research work deals with evolution of Cu doping concentration to the physical properties of ZnTe:Cu films in view of interface layer applications to CdTe solar cells wherein Cu content is taken as 1%, 3%, and 5%. The polycrystalline ZnTe:Cu thin films with thickness 200 nm were developed via resistive heating based thermal evaporation method on glass and ITO substrates followed by annealing in air ambient at 300 °C temperature for 1 h. The structural investigation revealed to (103) orientation as dominant reflection corresponding to zinc blende cubic phased structure where crystallite size is improved within range 36–53 nm. The optical energy band gap of the prepared ZnTe:Cu layers is attained within 2.34–2.57 eV range with varying Cu concentration and PL spectra depicted presence of two peaks centered at 351 nm and 451 nm wherein ZnTe:Cu 5% films showed better PL intensity. The I–V characteristics disclosed establishment of Ohmic contacts between the films surface and TCO layers concerned. The AFM micrographs of ZnTe:Cu films depicted hill-like topographies where hill height and intensity are enhanced for the ZnTe:Cu 5% films. The findings explicitly demonstrated that concentration of Cu dopant has radically persuaded physical properties and the ZnTe:Cu 5% films may be implicated as back contact interface layer to the device architecture concerned. [ABSTRACT FROM AUTHOR]

This study explores the use of Cu dopant to improve the optoelectronic properties and stability of CsPbX3 perovskites for blue-light-emitting diode material. The addition of Cu causes the metal octahedron of orthorhombic CsPbBr3 to shrink, which relaxes the lattice strain from the distortion and twisting of the [PbX6] octahedron and reduces energy from Jahn–Teller effects. A crystal orbital Hamilton population (COHP) analysis reveals that the Cu-Br bond in the [CuX6] octahedron has a higher integrated projected COHP (IpCOHP), and the strong hybridization between the Cu-3d and Br-4p bond enhances the bond interaction and the whole crystalline lattice. The addition of Cu dopants in CsPbBr3 perovskites results in a stronger framework that suppresses intrinsic defects like Br vacancies, leading to enhanced photoluminescence (PL) performance. Additionally, the Cu-3d orbitals contribute to the valence band and increase the band gap, resulting in a blue shift of the luminescence from Cu-doped CsPbBr3. These findings indicate that Cu dopants significantly improve the luminescence efficiency and the stability of CsPbBr3 perovskites, making them suitable for blue light LED applications.

• Cu nanoparticle decorated WS 2 film by MS+CVD. • Cu dopant both narrows the band gap and increases hole concentration. • Cu dopant increases the grain boundaries and reduces thermal conductivity. • Cu dopant synchronously regulates electrical and thermal properties. • ZT value up to 0.181 in Cu 5.5 -WS 2 film at 425 K. Thermoelectric materials have great potential in the energy recovery and environmental protection, and thermoelectric films can also effectively achieve heat dissipation of the chip through thermoelectric refrigeration. WS 2 films show good thermoelectric performance in prediction, but the figure of merit (ZT) of the synthesized WS 2 films still needs improvement. In this work, Cu was doped into WS 2 films by magnetron sputtering combined with chemical vapor deposition and sulfurization annealing. Cu doping narrowed the band gap and increased the hole concentration from 5.6 × 1019 cm−3 to 2.2 × 1021 cm−3, greatly improved the electrical properties of WS 2 film. At 300 K, the electrical conductivity and power factor of Cu-doped films increased by 1086 % and 575 % compared to pristine WS 2 , respectively. In addition, Cu doping reduced the grain size and introduced more grain boundaries, which decreased the in-plane thermal conductivity to as low as 0.22 W m−1 K−1 at 300 K. The coupling of the electrical and thermal properties optimization greatly improved ZT. The ZT value of Cu 5.5 -WS 2 films is as high as 0.181 at 425 K. This work provides a new idea for improving the thermoelectric performance of transition metal dichalcogenides (TMDCs) films. [ABSTRACT FROM AUTHOR]

In this work, a (ZnO)/(Cu-doped ZnO) core/shell nanorods array was fabricated by a two-step method: ZnO hydrothermal synthesis followed by encapsulation via a dip-coating process. The effects of the Cu dopant concentration on the structural, electrical and optical properties of the nanorods were studied. The SEM images showed that the encapsulation increased the nanorods average diameter from ~40 to ~60 nm. All ZnO core/shell nanorods showed a hexagonal wurtzite structure with no trace of a Cu oxide phase. A peak shift was observed in the XRD pattern, indicating the better Cu+ substitution into the Zn sites. The I–V measurements also showed that Cu doping up to 4.5 at.% decreased the samples resistance, which could be attributed to the +1 valance state of the Cu ions. It was also found that Cu doping increased the UV photoresponsivity of the photodetectors made by Cu:ZnO.

The rational design of cost-effective and highly active electrocatalysts becomes the crucial energy storage technology to boost the kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), which hinders the large-scale application of metal-air batteries under the situation of increasingly pressing energy anxiety. Herein, the Co-based ZIF introduced the moderate amount of Cu 2+ -derived Cu/Co metal nanoparticles (NPs) embedded in carbon frameworks after high-temperature calcination. The Co-O bond on the surface of Co nanoparticles is modulated by adjacent Cu nanoparticles with the surface Cu-O bonds. The resulted increase of the Co 2+ /Co 3+ ratio in 0.1CuCo-NC enhances the ORR/OER bifunctional catalytic kinetics along with the Δ E of 0.639 V. In situ Raman spectra of the catalyst on the three-electrode system as well as in the driven zinc-air battery (ZAB) show that the Co-O active sites regulated by Cu nanoparticles with Cu-O bonds maintain a periodic lattice expansion and compression during discharging and charging. The zinc-air battery based on 0.1CuCo-NC has a peak power density of up to 198.3 mW cm -2 , a mass-specific capacity of 798.2 mAh g -1 , and a cycling stability of 923 h at room temperature. This work makes up the research gap of a Co-based metal-organic framework (MOF)-derived catalyst regulated by a transition metal.

Herein, Cu was incorporated into ZnO lattice to reduce its band gap as well as to extend its visible radiation response. The obtained Cu-ZnO was continuously integrated with g-C 3 N 4 to create Cu-ZnO/g-C 3 N 4 Z -direct scheme photocatalyst for advanced atrazine removal. Radical scavenging experiments have been also conducted to clearly figure out photocatalytic mechanism for degradation of atrazine by the synthesized photocatalyst. The synthesized Cu-ZnO only utilized the generated h+ for atrazine degradation (direct and indirect via formation hydroxyl radicals (•OH)) and the g-C 3 N 4 only utilized the generated e− for atrazine degradation (indirect via reaction with O 2 to form superoxide anion, which needed to continuously react with H 2 O to form •OH). Therefore, the photocatalytic atrazine degradation by synthesized Cu-ZnO material was greater than that by synthesized g-C 3 N 4 material. Cu-ZnO/g-C 3 N 4 utilized both generated e− and h+ for degradation of atrazine. Thus, the photocatalytic atrazine degradation by the synthesized Cu-ZnO/g-C 3 N 4 was greater than those of single g-C 3 N 4 or Cu-ZnO materials. Finally, the conducted recycling experiments indicated great stability of synthesized Cu-ZnO/g-C 3 N 4 during long-term atrazine degradation process opening new era for application of the material in practical systems. Unlabelled Image • Cu doped into ZnO lattice to reduce its band gap and to extend its visible radiation response. • Cu-ZnO was successfully combined with g-C 3 N 4 to establish Z direct scheme system. • Z -scheme prevented fast recombination of e− and h+ and maintained their re-dox potential. • The Cu-ZnO/g-C 3 N 4 utilized both generated e− and h+ for degradation of atrazine. • The Cu-ZnO/g-C 3 N 4 showed excellent activity and stability during long-term photocatalysis. [ABSTRACT FROM AUTHOR]

Nanostructural morphology and cation (divalent or tetravalent) doping are known to be important factors for photocatalytic and photoelectrochemical activities of iron oxides. Modifications of iron oxides in an appropriate way could significantly improve these activities. In the present work the effects of Cu doping on the microstructural, thermal, optical and photocatalytic properties of goethite (α-FeOOH) and hematite (α-Fe 2 O 3) 1D nanoparticles were investigated. Goethite and Cu-doped goethite 1D nanoparticles were synthesized by precipitation in a highly alkaline medium. Hematite and Cu-doped hematite 1D nanoparticles were prepared by calcination of goethite samples at 500 °C. Cu2+-for-Fe3+ substitution in goethite and hematite was confirmed by determining the change in unit cell size using X-ray powder diffraction and by measuring the hyperfine magnetic field reduction using Mössbauer spectroscopy. An increased Cu2+-for-Fe3+ substitution in goethite caused a gradual elongation and narrowing of nanorods with the formation of nanoneedles at 3 or 4 mol% Cu. The shape and size of nanoparticles were not changed by thermal transformation of goethite to hematite. Thermal analysis showed a lower temperature of goethite dehydroxylation upon increased Cu doping. Cu2+-for-Fe3+ substitution in goethite and hematite caused increased absorption of visible and near-IR radiation beyond the absorption edge, as well as a slight decrease in direct and indirect optical band gaps compared with pure phases. The visible light photocatalytic activities of Cu-doped goethite and hematite nanoneedles were significantly improved compared with undoped goethite and hematite nanorods, which could be attributed to a combined effect of nanoneedle morphology and Cu doping. • Pure and Cu-doped α-FeOOH and α-Fe 2 O 3 1D nanoparticles were synthesized. • Cu2+-for-Fe3+ substitution in α-FeOOH and α-Fe 2 O 3 up to 4 mol% was confirmed. • A significant effect of Cu doping on different properties was observed. • Cu2+-for-Fe3+ substitution induced formation of nanoneedles at 3 or 4 mol% Cu. • These nanoneedles exhibited highly improved visible light photocatalytic activity. [ABSTRACT FROM AUTHOR]

We successfully used Cu to dope into the NiWO 4 crystal to prevent the fast recombination or increase the lifetime of the photo-induced h+ and e− of the material. Then, the synthesized Cu-NiWO 4 was successfully hybridized with g-C 3 N 4 to form Cu-NiWO 4 /g-C 3 N 4 direct Z system for novel photocatalytic decomposition of n-hexane under vis-light. In the formed Cu-NiWO 4 /g-C 3 N 4 Z direct system, photo-induced e− in Cu-NiWO 4 CB associated with photo-induced h+ in g-C 3 N 4 VB maintaining e− in g-C 3 N 4 CB and h+ in Cu-NiWO 4 VB, thereby synthesized photocatalysts formed abundant available e− and h+ amounts even excited by vis-light and the formed e− and h+ pairs exhibit suitable redox potentials for reactions with O 2 and H 2 O, respectively, to produce strong oxidative radicals for advanced photocatalytic degradation of n-hexane. The highest removal efficiency and degradation degree of n-hexane photocatalyzed by Cu-NiWO 4 /g-C 3 N 4 were 96.8 and 96.3%, respectively. The synthesized Cu-NiWO 4 /g-C 3 N 4 material also demonstrated strongly stability during long time n-hexane removal. Image 1 • Successfully doped Cu into NiWO 4 lattice to enhance its photocatalytic activity. • Cu dopant prevented recombination of photo-excited e− and h+ of the NiWO 4. • Cu-NiWO 4 was successfully combined with g-C 3 N 4 to establish Z direct scheme system. • Z-scheme prevented fast recombination of e− and h+ and remained their oxidative ability. • The Cu-NiWO 4 /g-C 3 N 4 exhibited excellent photocatalytic degradation of gaseous n-hexane. [ABSTRACT FROM AUTHOR]

Vertically aligned Cu-ZnO nanorod arrays were grown using thermal deposition method. Optimum Cu-ZnO and morphology tailoring effect was investigated. Enhanced photoelectrochemical (PEC) activity (0.92 ± 0.2 mA/cm 2 ) and high photon conversion efficiency (PCE) (0.3490 ± 0.2%) was observed for 5 wt% Cu-ZnO. Cu optimum dopant with ZnO lattice is a promising PEC candidate for water splitting applications. [ABSTRACT FROM AUTHOR]

Undoped and copper doped ZnO aerogels have been synthesized by the sol-gel method followed by supercritical drying in ethanol. The dopant contents in the aerogels were 1, 2, 3, 4 and 5 at.%. The as-obtained products were analyzed without any additional heat or chemical treatments. The XRD measurements revealed that aerogels have good polycrystalline ZnO hexagonal wurtzite structure with high crystalline quality. The data analysis showed that the crystallite sizes of ZnO and Cu-doped ZnO nanoparticles were within the range of 32-38 nm and the Cu dopant uniformly substitute for Zn sites. ATG measurements and EDAX studies showed that the aerogels have the extreme purity. SEM images revealed a snow-like morphology of the aerogels and the agglomeration state of the nanoparticles was not affected by Cu concentration. Optical absorption spectra showed a red shift of the absorption edge due to the merging of an impurity band into the conduction band. As the Cu content increases, the visible photoluminescence intensity decreases due to the scattering of the excitation radiation by surface-adsorbed dopant atoms and the non-radiative recombination process introduced by Cu impurity. The photoluminescence spectra of all aerogels showed one UV emission at 388 nm and a broad visible luminescence (490-650 nm) formed with two green (510 and 545 nm) and orange (612 nm) emissions. No shift observed with Cu concentration in emission positions in Cu-doped ZnO aerogels synthesized in supercritical ethanol. [ABSTRACT FROM AUTHOR]

In this paper, the effects of Cu dopant on CdO nanostructures grown through sonochemical method were investigated. Diffraction pattern analysis was determined CdO by the cubic structure for produced samples. Scanning electron microscope images showed that in the presence of Cu, the morphology of samples changed and the mean size of structures reduced. Transmission electron microscope has been used to compare the morphology and distribution size of un- and Cu-doped CdO nanostructures. Optical properties showed that there are different emission bands due to various transitions and emissions. Also, optical energy band gap value of the doped nanostructures is found to be in the range of 2.24–2.70 eV which reveals the presence of a blue shift. Electrical characterization also showed the lowest concentration of Cu dopant can create optimal electrical properties. It was found that Cu-doped CdO samples exhibited high photocurrent response as compared with the un-doped sample. Also we have seen n-type conductivity for obtained CdO nanostructures. [ABSTRACT FROM AUTHOR]

The SiO nanoparticles doped by 10 % mol Cu were prepared via a sol-gel method under process control. The effects of doping and calcination temperature on the structural and photo-catalytic properties of SiO nanopowders have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis absorption spectroscopy. Cristobalite and tridymite crystalline phases were found at a calcinations temperature range of 900∼1200 °C and amorphous phase was formed at a temperature of 800 °C for doped SiO. The photocatalyst activity was evaluated by photocatalytic degradation kinetics of aqueous methyl orange (MO) under visible radiation. The results show that the photocatalytic activity of the 10 % mol Cu doped SiO nanopowders have a larger degradation efficiency than pure SiO under visible light at 900 °C temperature. [ABSTRACT FROM AUTHOR]

TiO nanopowders doped by Cu were prepared by the sol-gel method. The effects of Cu doping on the structural, optical, and photo-catalytic properties of titania nanopowders have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO. Titania rutile phase formation in the system (Ti-Cu) was promoted by Cu doped TiO. The photo-catalytic activity was evaluated by photo-catalytic degradation kinetics of aqueous methylene orange (MO) under visible radiation. The results show that the photo-catalytic activity of the 5 %Cu doped TiO nanopowders has a larger degradation efficiency than pure TiO under visible light. Also, the minimum band gap was estimated to be ∼ 1.9-2 eV from UV-Vis spectra. [ABSTRACT FROM AUTHOR]

Cu-doping into Zn 1−x Cd x S can greatly enhance the photocatalytic H 2 evolution from water splitting under visible-light irradiation. However, it is still controversial for how the Cu-dopant improves this performance. Here, we report that appropriate Cu-doped Zn 0.5 Cd 0.5 S nanocrystals reach 21.4 mmol/h/g of H 2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart, and the corresponding apparent quantum efficiency is 18.8% at 428 nm. It is firstly confirmed that the Cu 2+ changes into Cu + after being doped by soft X-ray absorption spectroscopy (sXAS). We theoretically propose that the transformation of 2Cu 2+ to 2Cu + results in one adjacent S 2 − vacancy (V S ) in host during the doping process, while the Cu + -dopant and V S attract the photoexcited holes and electrons, respectively. Accordingly, the photocatalytic activity is improved due to the enhanced separation of photoexcited carriers accompanied with the enhanced light absorption resulting from the Cu + -dopant and 2Cu + /V S complex as possible active site for photocatalytic H 2 evolution. [ABSTRACT FROM AUTHOR]

To improve the tribological properties of WS film both in vacuum and in humid air conditions, its microstructure was optimized by doping different concentrations of Cu via radio frequency co-sputtering method. The film microstructure and composition were investigated by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, grazing incidence X-ray diffraction and high-resolution transmission electron microscopy. It was verified that Cu was presented in amorphous phase in the WS matrix and could also induce amorphization and densification of the composite films gradually. The film microstructure changed from coarse columnar platelet structure at low Cu content (0-5.8 at.%) to transition structure with two separate layers at increased Cu content (11.5-16.2 at.%) and to a featureless structure at high Cu content (above 24.4 at.%). The mechanical and tribological properties of films were evaluated using the scratch tester and ball-on-disk tribometer, respectively. It was found that the incorporation of a suitable content of Cu dopant could significantly improve the film toughness, but excess amount of Cu dopant lead to high brittleness. All the composite films exhibited much lower wear rate and longer wear life than those of pure WS film both in vacuum and in humid air conditions. The wear mechanisms were proposed after correlating the mechanical performance with film microstructure. [ABSTRACT FROM AUTHOR]

• Influence of Cu doping on properties of CdSe films is investigated for solar cells. • Structural study unveils boost in crystallite size from 38 to 52 nm with Cu doping. • Enhanced visible light absorption and refractive index are found for 5% Cu doping. • Morphological study showed elongated and nanospherical grains with grain growth. • I-V plots confirm Ohmic nature and EDS patterns validate deposition of CdSe:Cu films. Incorporation of foreign dopant in CdSe host lattice is fascinating approach to tune absorbance, grain-size, conductivity, morphology, topography and stoichiometric-compositions for absorber layer solar cell applications. Herein, thin films of CdSe:Cu alloys having 1%, 3% and 5% Cu contents are grown using thermal-evaporation technique and subsequently annealed at 350 °C. Structural exploration unveils phase-transformation from (103) orientation of hexagonal to (111) orientation of cubic CdSe at 3% and 5% Cu doping with appropriate substitution of Cd2+ by Cu2+ ions at 5% Cu doping. Different Cu concentrations considerably affect optical-response where higher Cu doping leads to augment in refractive-index and visible-light-absorption. PL spectra exhibit two peaks with stronger near-band-edge luminescence at ∼685 nm. Two-dimensional AFM micrographs show spherical-elliptical grains at lower Cu concentration whereas agglomerated-interlinked grains at higher concentration. FESEM micrographs display elongated-nanospherical grains having size in 45-60 nm range. Thus, present investigation offers comprehensive insights for tailoring properties of CdSe films with Cu dopant for solar cells. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Cu doped CdS nanocrystalline thin films were prepared by the sol–gel dip-coating method incorporated in polyethyleneglycol matrix. After heat treatment in air at 250 and 350°C, the prepared thin films were investigated by studying their structural, morphological, compositional, optical (linear and nonlinear) and photoluminescence properties. X-ray diffraction (XRD) results suggest that the samples are polycrystalline in nature with hexagonal crystal structure and the average grain size is in the range of 15–19nm. The surface morphology of the films was examined by scanning electron microscopy (SEM). The results showed that the films consist of nanocrystalline grains included in the clusters with uniform coverage of the substrate surface. To examine the chemical composition of the films, the X-ray photoelectron spectra (XPS) of the composite films were measured. It was found that the transmittance and the band gap decreased totally as the Cu concentration/annealing temperature increased. The refractive index of the films was studied and the related dispersion was discussed in terms of the Wemple–Didomenico single oscillator model. The third-order nonlinear polarizability of the films was estimated through a semi-empirical relation based on single oscillator model and the results showed that the prepared films are proper to use as optical switch. For photoluminescence (PL) study, 200 and 365nm excitation wavelengths were examined and compared together. The intensities of emission peaks for the prepared thin films varied with Cu doping/annealing temperature and the behaviors of different band peaks were discussed with giving reasons. [Copyright &y& Elsevier]

Abstract: Pure and Cu-doped ZnO nanofibers were synthesized via electrospinning technology. The morphology and structure of the as-synthesized nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The effects of Cu doping on H2S sensing properties at low concentration (1–10ppm) were investigated at 230°C. The results show that the H2S sensing properties of ZnO nanofibers are effectively improved by Cu doping: 6at% Cu-doped ZnO nanofibers show a maximum sensitivity to H2S gas, and the response to 10ppm H2S is one order of magnitude higher than the one of pure ZnO nanofibers. [Copyright &y& Elsevier]

Abstract: We prepared nickel oxide (NiO) thin films with p-type Cu dopants (5at%) using a sol–gel solution process and investigated their structural, optical, and electrical characteristics by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmittance and current–voltage (I–V) characteristics. The crystallinity of the NiO films improved with the addition of Cu dopants, and the grain size increased from 38nm (non-doped) to 50nm (Cu-doped). The transmission of the Cu-doped NiO film decreased slightly in the visible wavelength region, and the absorption edge of the film red-shifted with the addition of the Cu dopant. Therefore, the width of the optical band gap of the Cu-doped NiO film decreased as compared to that of the non-doped NiO film. The resistivity of the Cu-doped NiO film was 23Ωm, which was significantly less than that of the non-doped NiO film (320Ωm). Thus, the case of Cu dopants on NiO films could be a plausible method for controlling the properties of the films. [Copyright &y& Elsevier]

• Successfully doped Cu into ZnO lattice to enhance its photocatalytic activity. • Cu dopant prevented recombination of photo-excited e− and h+ of the ZnO. • The Cu-ZnO exhibited excellent photocatalytic degradation of monocrotophos pesticide. • The optimal mole ratio of Cu/ZnO in the Cu-ZnO for degradation of monocrotophos was 3%. • The optimal pH for the photocatalytic degradation of monocrotophos was pH 7. In the work, we successfully synthesized Cu doped ZnO materials for photocatalytic degradation of monocrotophos pesticide (MCP). The used Cu metal doped into the ZnO matrix created an intermediate band to excite electron from valence band (VB) to conduction band (CD) of the ZnO leading to increase in optical absorption, decrease in band gap as well as photocatalytic performance of the material. Hence, the synthesized photocatalyst showed intense activity for photocatalytic degradation of MCP into CO 2 , H 2 O and harmless inorganic ions even under visible radiation. We also investigated that the 3Cu-ZnO photocatalyst, which the weight ratio of Cu/ZnO was 3 wt%, showed the highest MCP degradation efficiency among these synthesized Cu-ZnO. The excess dopants tended to form CuO existing on ZnO surface. The formed CuO acted as a center for recombination of produced electrons and holes resulted in decrease in photocatalytic performance of the Cu-ZnO. Finally, we investigated that the optimal pH for the degradation of MCP by the synthesized Cu doped ZnO photocatalyst was pH 7. [ABSTRACT FROM AUTHOR]

• Successfully doped Cu into NiWO 4 crystal to improve its photocatalytic ability. • Cu dopant prevented e−/h+ recombination of the NiWO 4. • The Cu-NiWO 4 exhibited excellent photocatalytic degradation of gaseous benzene. • The optimal mole ratio of Cu/Ni in the Cu-NiWO 4 for benzene removal was 3%. • The Cu-NiWO 4 removed 97% benzene and mineralized 96.5% of them into CO 2 and H 2 O. We effectively used Cu dopant to improve photocatalytic performance of NiWO 4 to remove benzene in air. The obtained experimental result indicated that photocatalytic performance of the prepared Cu-NiWO 4 materials were greater than that of the pure NiWO 4. This was because Cu effectively acted as novel dopant, which not only affected valence band (VB) top and conduction band (CB) bottom of NiWO 4 but also formed a medium energy level between CB and VB of the NiWO 4 to decrease its energy band gap and electron-hole recombination rate. Hence, the photocatalyst produced large available charge amounts (electron and hole) initiating photocatalysis for degradation of gaseous benzene. The optimized Cu/Ni mole ratio for maximum improving photocatalytic performance of NiWO 4 was 3%. The maximum benzene removal efficiency and its mineralization via visible light photocatalysis of the 3Cu-NiWO 4 were 93.7 and 96.5%, respectively. The synthesized Cu-NiWO 4 photocatalyst also presented great stability in benzene removal processes. [ABSTRACT FROM AUTHOR]

Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films, and the best conductivity is achieved with a high hole concentration of 1.54 × 10(18) cm(-3), a low resistivity of 0.6 Ω cm, and a moderate mobility of 6.65 cm(2) V(-1) s(-1) at room temperature. Metal oxide semiconductor capacitor devices have been fabricated on the Cu-doped ZnO films, and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as X-ray diffraction, X-ray photoelectron, Raman, and absorption spectroscopies are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO.