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• CuO BNWs were synthesized by oxidant-free, room temperature surface oxidation method. • CuO morphology evolves from particles to layered nanoflakes to bundles of nanowires. • CuO BNWs electrode shows excellent specific capacitance of 509 F/g at 1 A/g. • The all solid state device obtained high s p e c i f i c e n e r g y of 22.57Wh/kg at s p e c i f i c p o w e r of 1.29 kW/kg. • The all solid state device exhibits 83.2 % capacitive retention over 5000 GCD cycles. In the present work, copper oxide bundles of nanowires (CuO BNWs) were synthesized by room-temperature surface oxidation of an electroplated Cu layer in an alkaline bath. The time-dependent morphological evolution of CuO BNWs is systematically achieved by varying surface oxidation times. The CuO BNWs provide a high surface area (19.12 m2/g) and have shown excellent supercapacitive performance with a specific capacitance of 509 F/g at 1 A/g current density owing to fast electron transfer paths offered by BNWs. The all-solid-state hybrid supercapacitor device (SS//Cu//CuO-BNWs//KOH-PVA//rGO) demonstrates a specific capacitance of 77.3 F/g and energy density of 22.57 Wh/kg at a power density of 1.29 kW/kg. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-sacrificial template-directed method to prepare mesoporous CuO micro/nanoplates. • CuO plates are examined as a highly efficient photo-Fenton-like catalyst. • 100% sulfathiazole degradation and 87.3 % TOC removal under vis LED irradiation. • Excellent reusability up to the five cycles. In this study, we offer a simple self-sacrificial template-directed method to prepare mesoporous CuO micro/nanoplates by using copper hydroxide acetate (Cu 2 (OH) 3 (CH 3 COO)·H 2 O) plates as a template. The as-prepared material was structurally, morphologically, optically and texturally characterized and its excellent catalytic activity in the LED-driven photo-Fenton-like process of sulfathiazole oxidation was demonstrated. Within 90 min, 100 % sulfathiazole degradation and 87.3 % TOC removal were achieved in the presence of H 2 O 2 and visible LED irradiation. Moreover, the degradation of sulfathiazole can still reach 96.1 % after five cycles, which indicates exceptional performance of the catalyst. [ABSTRACT FROM AUTHOR]

• A new photocatalyst InGaZn 0.3 Cu 0.7 O 4 with CuO to decompose tetracycline efficiently. • The Cu2+ doping in InGaZnO 4 significantly improves the light absorption properties. • The layered structure of InGaZn 0.3 Cu 0.7 O 4 is conducive to the enhancement of photodegradation performance. Herein, we reported a new photocatalyst InGaZn 0.3 Cu 0.7 O 4 with co-catalyst CuO for the photo-oxidation of tetracycline. Copper doping in InGaZnO 4 significantly reduced the bandgap and enhances the absorption of visible light. The photocatalytic performance was further enhanced by making a composite with CuO. In the photo-oxidation reaction of tetracycline, the kinetic constant of the optimal composite is 0.0111 min−1, which is 3.0 and 10.1 times higher than those of InGaZnO 4 and InGaCuO 4 , respectively. The photocatalytic mechanism suggested that photogenerated holes play the most important role in the oxidation of tetracycline. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CuO/MgO/ZnO NPs have been successfully synthesised from the Costus pictus D. Don plant. • CuO/MgO/ZnO NPs showed inhibitory activity against different bacteria. • The negative zeta potential confirms the stability and dispersion of CuO/MgO/ZnO NPs. • The CuO/MgO/ZnO NPs have significant surface area displaying their anti-bacterial potential. In recent years, environmentally friendly methods have garnered significant attention in developing novel nanoparticles (NPs). This study focuses on the green synthesis and characterisation of CuO/MgO/ZnO NPs using Costus pictus D. Don Plant extract as a green reducing and capping agent. X-ray diffraction (XRD) analysis was employed to assess the purity of NPs, whereas Fourier-transform infrared (FTIR) and UV–Vis spectroscopy were employed to study the chemical composition and absorption peaks of the synthesised NPs. The Field-emission scanning electron microscopy (FE-SEM) images revealed a distinctive flower-like morphology of NPs, and their stability and dispersion were supported by a negative zeta potential of −14.8 mV. The significant surface area (87.742 m2/g) of CuO/MgO/ZnO NPs was obtained from Brunauer-Emmett-Teller (BET) analysis. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analysis confirmed that the particle size of NPs is nearly 50 nm and is poly-crystalline. Finally, the synthesised NPs were tested against the bacteria using the agar-well diffusion method. Notably, CuO/MgO/ZnO NPs exhibited better antibacterial activity against Pseudomonas aeruginosa , yielding a substantial inhibition zone of 23.33 ± 2.08 mm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Monoclinic CuO 1-x nanoflakes were synthesized using a facile and green route. • Monoclinic CuO 1-x nanoflakes showed superior NO sensing performance at room temperature. • The mechanism was proposed based on abundant oxygen species (O C and O V), and grain boundary modulation. The rich-oxygen vacancy CuO nanoflakes (CuO 1-x) were prepared via a facile hydrothermal synthesis method. The characterized results showed that CuO 1-x were obtained with the thickness of ∼ 90 nm, which were also closely linked. The CuO 1-x based gas sensor showed good sensing performance to 0.5–5 ppm NO at ∼ 25 °C. The response (S = R a /R g) of CuO 1-x sensor was 21.8 to 5 ppm NO, while that to 0.5 ppm NO was 1.5. Moreover, the gas sensor demonstrated excellent low limit of detection (383 ppb), good selectivity, and long-term stability. The NO sensing mechanism of CuO 1-x was discussed based on abundant oxygen species (O C and O V), and grain boundary modulation. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) loaded titanium dioxide (TiO 2 ) nanotube photocatalyst was synthesised using the facile hydrothermal method. The synthesised photocatalyst were characterised by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) to study their physiochemical properties. The photocatalytic activity of the photocatalysts was tested for carbon dioxide (CO 2 ) photoconversion into fuels. CuO loaded TiO 2 nanotube demonstrated higher CO 2 conversion (100%) than TiO 2 nanotube (72.20%) because of the former’s effective separation of photogenerated electron-hole pairs in the presence of CuO. [ABSTRACT FROM AUTHOR]

In this study, a template-assisted approach for novel hierarchical CuO nanoflowers with Cu 2 O nanocubes as the templates was designed and carried out. The structures and morphologies in different growth processes were studied by various characterization methods, showing that these hierarchical CuO nanoflowers consisted of ultrathin nanosheets. The hierarchical CuO nanoflowers serving as active materials illustrated great performances for non-enzymatic glucose sensing with high sensitivity of 2217 μA mM −1  cm −2 , low detection limit of 0.96 μM and wide linear range up to 6 mM. Moreover, the electrodes exhibited quick response time, long term stability, good selectivity and acceptable practice workability, suggesting the great potential of the as-prepared CuO nanoflowers in non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

We report on the in-situ chemical growth of unique core-shell quantum dots (QDs) with single layer graphene on the surface of CuO QDs and their structural, optical and electrical properties. The CuO/graphene QDs were synthesized through a simple and hydrothermal technique. In order to enhance performance electrochemical energy storages, we have developed core (active material)/shell (conductive material) type CuO/graphene QDs as electrode materials using the combined electrolytes (KOH + LiCl). As a result, the performance of electrochemical energy storages exhibits specific capacitance of 154 F g −1 at current density of 1 A g −1 and cycling stability with 84% capacitance retention after 3,000 cycles. [ABSTRACT FROM AUTHOR]

A facile one-step microwave-assisted synthetic route was developed to prepare ultrathin and defect free CuO nanosheets without any surfactant. During the synthetic process, the 100 mL of water and ethanol mixed solution (1/1, v/v) containing 0.86 g of CuCl 2 ·2H 2 O and 2 g of sodium hydroxide was heated by microwave irradiation at a power of 750 W for 20 min. Most of these CuO sheets possessed a length of 80–110 nm, 40–60 nm in width, and only 11 nm in thickness. The microstructure and morphologies of the CuO product were investigated in details by XRD, SEM, HRTEM, FT-IR, and XPS techniques, and it was found that the shapes of CuO were dependent on the concentrations of sodium hydroxide. The band gap of such CuO nanosheets was estimated to be 2.17 eV according to the UV–vis absorption curve. This effective microwave-assisted approach may be a promising route to prepare other transition metal oxides. [ABSTRACT FROM AUTHOR]

Development of new photocatalysts with high catalytic efficiency, catalytic stability, and visible-light activity is very important for environmental decontamination and clean energy production. Here, we show the preparation of a composite photocatalyst of ordered mesoporous carbon (OMC)-CuO by a solution impregnation method with OMC as the carrier. The novel combination of CuO nanaoparticles and OMC exhibit not only a high visible-light catalytic activity and excellent surface adsorption property, but also a catalytic stability. The photodegradation efficiency of OMC-CuO for rhodamine B is 97.2% under visible-light irradiation, and higher than pure TiO 2 and CuO nanaoparticles. [ABSTRACT FROM AUTHOR]

Nanowire arrays of copper oxide were first grown vertically using simple and cost effective thermal oxidation method on a copper foil. Subsequently, in order to deposit and grow PbS nanocyrstalline thin films on CuO NWs by utilizing the chemical bath deposition technique, these arrays were immersed as the substrate in the reaction solution consisting of Pb(NO 3 ) 2 , (NH 2 ) 2 CS and NaOH. The final products were characterized in detail by which the formation of uniform, unique arrays of CuO@PbS core–shell NWs was confirmed. Due to the nature of methods employed in synthesis of this hetero structure, the tuning of core and shell size and consequently properties of the novel structure is easily possible by changing synthesis parameters. [ABSTRACT FROM AUTHOR]

Highlights • The CuO crystal was synthesized at room temperature. • The leaf-like, featheriness structure, and flake-like were got. • The synthetic process was very simple and non-toxicity. Abstract CuO is an attractive p-type semiconductor due to narrow band gap, low cost, and easy availability. In this paper, we obtained CuO crystals through a simple sol-gel method at room temperature. The samples were proved to be pure CuO crystals through the X-ray diffraction and Raman measurement. The reaction time and OH− concentration played a critical role in the structure and morphologies of pure CuO crystals. Through adjusting of the pH value, several different morphologies, including leaf-like, featheriness structure, and flake-like, were obtained. This paper provided a very simple, low cost and environmentally friendly method to control the morphologies of CuO. [ABSTRACT FROM AUTHOR]

The detection of H 2 S gas at low concentrations for the diagnosis of halitosis is examined. The H 2 S sensor is composed of CuO nanorods decorated with Fe 2 O 3 nanoparticles. Diagnostic sensors must be able to detect gases in low concentrations. Therefore, to produce a highly sensitive device, CuO nanorods were decorated with metal oxide semiconductor nanoparticles, which doubled the sensitivity. In addition, the selectivity of the sensor improved in comparison with that of the bare CuO nanorod sensor. Here we report the fabrication and testing of a hybrid-structured gas sensor for detecting H 2 S gas at low concentrations. Furthermore, we report the mechanism by which the sensitivity of the composite sensor is improved. [ABSTRACT FROM AUTHOR]

Three-dimensional porous graphene/carbon nanotubes (CNTs)/CuO (GCC) hybrid aerogel was constructed through hydrothermal treatment. After been mechanically compressed, the aerogel showed a paper form and revealed a relatively ordered layer by layer structure with CuO and CNTs intercalated. When used as anode for lithium ion batteries, the unique structure not only provided electrically conducting channels to promote electrolyte penetration, but also could buffer the volume expansion during lithium ion insertion/extraction process. Thus, the resultant binder-free GCC aerogel paper anodes demonstrated excellent cyclic retention with the specific capacity of 636.9 mA h g −1 after 80 cycles compared to pure CuO, as well as excellent rate performance for lithium storage. [ABSTRACT FROM AUTHOR]

CuO@Cu 3 (BTC) 2 composite (BTC=benzene-1,3,5-tricarboxylate) was synthesized via a facile self-template method using CuO as the precursor. Cu 3 (BTC) 2 is a representative MOF (metal-organic framework), which is a class of crystalline inorganic–organic hybrid materials. By controlling synthesis time, CuO@Cu 3 (BTC) 2 with different content of Cu 3 (BTC) 2 was obtained. The products were characterized by X-ray diffraction (XRD), thermogravimetric (TG) analysis, transmission electron microscopy (TEM) and N 2 sorption measurement. It suggested that when controlling longer synthesis time, CuO@Cu 3 (BTC) 2 contained more Cu 3 (BTC) 2 and showed larger surface area and total pore volume. CuO@Cu 3 (BTC) 2 can effectively catalyze oxidation of cumene to cumene hydroperoxide (CHP) and the yield of CHP reached 18.1%, which was better than 13.6% by CuO or 8.7% by Cu 3 (BTC) 2 . When the ratio of CuO:Cu 3 (BTC) 2 in CuO@Cu 3 (BTC) 2 was 1:0.073 and 1:0.115, CHP yield was 18.1% and 14.2%, respectively. This study provides an approach for the oxidation of alkyl benzene using metal-oxide@MOF composite as catalyst. [ABSTRACT FROM AUTHOR]

• Facile fabrication of CuO catalyst via a simple hydrothermal method. • CuO/PMS system exhibited high efficiency for elimination of aqueous organic pollutants. • The co-existing anions and small molecule acids affected the activity of CuO/PMS system. • SO 4 •- and •OH played an important role in the degradation of organic pollutants. CuO was prepared via a simple hydrothermal method and characterized by several characterization techniques. The prepared CuO had high efficiency for elimination of organic pollutants by activation of peroxymonosulfate (PMS), more than 97 % methylene blue (MB) was degraded in 20 min. Quenching experiment indicated that SO 4 •- and •OH all contributed to MB degradation. Besides, the effects of CuO dosage, PMS concentration and initial pH on the removal of MB were investigated in detail. The co-existing anions and humic acid inhibited the activity of CuO/PMS system. In addition, CuO/PMS system possessed excellent ability for MB degradation in tap water and lake water, and excellent performance in the degradation of methyl orange and tetracycline hydrochloride. Overall, CuO activating PMS is a promising technique for the removal of organic pollutants from complex background. [ABSTRACT FROM AUTHOR]

• Au nanoparticles loaded CuO nanorods were prepared by an easy two-step method. • The CuO nanorod could be loaded with a single gold nanoparticle. • The 2 mol% Au@CNRs exhibited room-temperature NO 2 sensing properties. • Enhancement mechanism of Au loading was discussed by activation energy theory. The problem of high operating temperature and high power consumption in practical detection has been existing in semiconducting CuO based gas sensors. With sensitization of noble metals, Au nanoparticles loaded CuO nanorods with different concentrations were prepared with an easy two-step method. The crystal structure, morphology, nanosize, and chemical composition of the samples were examined by XRD, FESEM, TEM, and XPS respectively. The CuO nanorod was loaded with a single gold nanoparticle with the Au-loading concentration of 2 mol%. This 2 mol% Au loaded CuO nanorod sample exhibited enhanced NO 2 sensing performance, which can obtain the same peak response 4.3 to 5 ppm NO 2 at a lower temperature of 100 °C as compared with that of the pure CuO nanorods at 150 °C. Meanwhile, the response/recovery speed and selectivity were also promoted. More importantly, Au loaded CuO nanorods can realize NO 2 detection in room temperature (25 °C). The low-temperature sensitization mechanism with Au-loading was also investigated. [ABSTRACT FROM AUTHOR]

• A large scale CuO film is prepared on Si substrate tightly by ozone etching and annealing. • The film consists of a dense polycrystalline nanoplate array. • The film is fabricated into a schottky contacted diode with Al electrodes. • The diode performs a large rectifying ratio and a highly sensitive. Schottky contacted sensors are of promising photoelectric devices due to the intrinsic high selectivity and high sensitivity properties. However, it is still a challenge to construct a stable contacted semiconductor material in Schottky sensors. In this work, a CuO film was prepared by an ozone etching and annealing on a silicon wafer substrate. Material characteristic investigation shows that the film composed of a highly dense polycrystalline nanoplate arrays film. The film is also used to fabricate a schottky diode with aluminum electrode to test its photoelectric performance. The test results indicate that the diode has a large rectifying ratio and a highly sensitive photoreponse effect. This work provides a new facile CuO nano arrays material process for Schottky contacted sensor application. [ABSTRACT FROM AUTHOR]

• Strain induced bandgap engineering in CuO nanoparticles (NPs) • Competing microstrain over size for CuO NPs. • Bandgap reduction from 3.62 eV to 3.00 eV with reducing CuO NPs size from 92 to 37 nm. The phase pure monoclinic copper oxide (CuO) nanoparticles (NPs) are synthesized, and the observed strain strongly affects bandgap, leading to its reduction from 3.62 eV to 3.00 eV (±0.02 eV) by reducing the crystallite size from 92 to 37 nm (±5 nm), in contrast to the geometrical size effect, where bandgap (E g) increases with decreasing particle size. This exciting characteristic is attributed to the dominant micro-strain effect over the size on electronic properties of CuO nanoparticle systems, proving a new way of strain mediated bandgap engineering in NP systems. [ABSTRACT FROM AUTHOR]

A facile route was developed for the preparation of porous hexapod CuO nanostructures based on a solvothermal route with subsequent calcination. The CuO nanostructures are composed of numerous nanopaticles with high porosity resulting from the thermal decomposition of the Cu 2 O-CNTs precursors. The obtained CuO hexapod nanostructures were evaluated for their ability for the degradation of phenol under visible-light irradiation. Comparing with commercial CuO and P25, the as-prepared CuO hexapod nanostructures exhibit superior property on the photocatalytic decomposition of phenol. It is believed that the efficient photocatalytic property is originated from their unique 3D porous nanostructures which are highly beneficial to the reagent diffusion and mass transportation. [ABSTRACT FROM AUTHOR]

The present investigation reports a simple solution process for synthesizing the leaf-like hierarchical CuO nanosheets without using a surfactant/template at low temperature. The crystalline structure, morphology and the UV light absorption capability of leaf-like hierarchical CuO nanosheets were examined. The UV light absorption capability was estimated by dispersing few percentage of leaf-like CuO nanosheets in a polymer film. An excellent UV light absorption capability was witnessed in a polymer film containing 0.2% of leaf-like CuO nanosheets with the maximum of 68% and 66% under a UV lamp and the direct daylight sources, respectively. [ABSTRACT FROM AUTHOR]

Well-crystalline cocoon-shaped CuO nanostructures were synthesized by simple solution process and used as an efficient heterogeneous photocatalyst for the degradation of harmful organic dye under UV light irradiations at room-temperature. The as-synthesized CuO nanococoons were characterized in detail using several techniques which revealed that the prepared nanostructures are well-crystalline, grown in very high density and possessing monoclinic crystal structure. Further, as a photocatalyst, the CuO nanococoons exhibited reasonable photocatalytic degradation toward harmful organic dye, i.e . acridine orange (AO). The kinetic study revealed that the photocatalytic degradation of AO using CuO nanococoons as photocatalyst follows a pseudo-first order kinetics. [ABSTRACT FROM AUTHOR]

Copper powders were thermally treated in the air at a wide temperature range of 200–700 °C. It was found that thin CuO nanowires were grown at 300 °C and thick CuO nanowires were grown at 500 °C. The diameters of the thin CuO nanowires were distributed in the range of 5–10 nm, and the growth directions along [1̄11] and [110] were observed. In addition, the thermally treated copper powders with ultrathin CuO nanowires showed a broad violet emission band peaking at 402 nm. [ABSTRACT FROM AUTHOR]

In this article, the investigations on the doping of cupric oxide (CuO) nanorods with Zn(II) ions and their photocatalytic properties have been reported. The Zn doped CuO nanoflowers were synthesized by hydrothermal method using three different concentrations of Zn (II) ions, without structure directing agent. The presence of Zn ions exhibits CuO growth with monoclinic structure which favors the formation of nanoflowers morphology. The crystalline structure, morphology and the optical properties of the obtained nanostructures were characterized using XRD, FESEM/EDX and UV-visible spectrometer. The photocatalytic performance of the prepared Zn-CuO nanoflowers was examined for the degradation of methylene blue (MB) and methylene violet (MV) under UV irradiation. 0.07 M Zn-CuO nanoflowers exhibited the highest degradation rate of 1.7175 h −1 for MB and 2.383 h −1 for MV. [ABSTRACT FROM AUTHOR]

• Stellite 6 reacted with CuO at 1200 °C in pure argon to produce gases and oxides. • The oxides contain CoO, Cr 2 O 3 , SiO 2 , MnO 2 and CoCr 2 O 4 /NiCr 2 O 4 /Fe 3 O 4. • Many defects exist at the interface between the Stellite 6 alloy and the oxide. • Excessive defects indicate a negligible adhesion between the oxide and Stellite 6. The interfacial reaction of Stellite 6 alloy with CuO at 1200 °C in pure argon was investigated. The bubbling phenomenon was observed during the reaction. The results show that the reaction produced solid oxides (CoO, Cr 2 O 3 , SiO 2 , MnO 2 and CoCr 2 O 4 /NiCr 2 O 4 /Fe 3 O 4) and pure copper, as well as possible CO and CO 2 gases. The product gases and oxides caused holes and cracks in the sample. [ABSTRACT FROM AUTHOR]

Abstract: Copper oxide nanostructures with different morphologies from bundle of sheets to nanofibres were synthesized by a chemical method. Pyridine was used as a morphology directing agent and the role of its concentration was investigated. In the absence of pyridine, bundles of nanosheets were obtained. Addition of pyridine in various concentrations had a profound effect on the morphology. The high dispersion ability of pyridine led to the separation of particles and decrease in grain size. The grain size decreased with increase in ligand concentration. Structural studies revealed the formation of monoclinic CuO. The possible mechanisms for the formation of these nanostructures were explained with the help of electron microscopic techniques. The obtained CuO nanostructures had high crystalline nature with fascinating functional properties. [Copyright &y& Elsevier]

Abstract: In this study, hollow copper oxide microspheres were synthesized by a simple and low cost co-precipitation reaction of Cu(NO3)2·3H2O and ammonia without catalyst, template or surfactant. The prepared CuO was characterized by XRD, FT-IR spectroscopy, DRS and SEM images. The morphology of the CuO powder consists of Hierarchical dandelion-like structures contain one-dimensional nanoribbons with the average size of 20–30nm according to SEM images. The XRD pattern showed that the synthesized CuO nanostructures have a high crystallinity with monoclinic crystal structure. The prepared CuO was applied for photodegradation of methylene blue under UV and visible light irradiation and showed good photocatalytic performance to degrade the dye (for 5mgL−1 MB solution: 97.3% degradation). [Copyright &y& Elsevier]

Abstract: Novel porous spherical CuO xerogels constructed by crystalline nanorods (100–200nm in length and 20–40nm in diameter) are synthesized as anode materials in lithium-ion batteries. Aided with the soft-template of P123, the product possesses abundant mesopores centered at ~7.3nm and high surface area of 63.1m2 g−1. Benefiting from its structural features, including porous structure, one-dimensional structure, and oriented growth along (111) plane, the presented sample delivers high reversible capacity (646.7mAhg−1 at 0.2C after 150 cycles), excellent cyclic performance (88% capacity retention after 150 cycles), and superior rate capability (510mAhg−1 at 0.5C). [Copyright &y& Elsevier]

Abstract: CuO nanoparticles are directly formed on graphene nanosheets through the in situ chemical decomposition of Cu(NO3)2·3H2O and are anchored tightly on the graphene surface. The lithiation-induced strain is naturally accommodated, owing to the constraint effect of the graphene matrix. Electrochemical characterization shows that CuO nanoparticles anchored on graphene sample exhibits a high capacity of about 660mAh/g at a discharge current density of 100mA/g and a good cycling ability. During the charge–discharge process, graphene nanosheets not only served as a three-dimensional conductive network for CuO nanoparticles, but also improve the detachment and agglomeration of CuO nanoparticles. This CuO/graphene nanocomposite displays superior Li-battery performance with large reversible capacity, excellent cyclic performance, and good rate capability. [Copyright &y& Elsevier]

Abstract: The uniform hierarchical 3D flowerlike copper oxide (CuO) nanostructures, which were composed of interconnected nanowires, have been successfully prepared via a reverse microemuclsion method. The detailed morphology and structure of the synthesized hierarchical nanostructures were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). A series of observed intermediates disclose the possible process of forming 3D flowerlike CuO. An oriented aggregation growth process mediated by the microemulsion droplet building blocks might take place during the formation of initial 3D flowerlike CuO. And the novel 3D flowerlike and straw-like CuO nanostructures are produced as reaction time goes on, which might experience an Ostwald ripening process. [Copyright &y& Elsevier]

Abstract: SnO2/CuO nano-hybrid foam sensors were fabricated through thermal oxidation of Sn–Cu foam synthesized by electrochemical deposition, and their gas sensing properties were investigated. The macro-porous Sn–Cu foam was formed during electrodeposition, and its pore wall was composed of self-supported nano-sized dendrites. The annealing at 700°C converted the Sn–Cu foam into the SnO2/CuO nano-hybrid foam with preserving the structural integrity and pore structure. The SnO2/CuO nano-hybrid foam sensor responded to the reducing gases such as H2, CO, NH3, NO x , CH5OH, and H2S, but the foam sensor exhibited two orders of magnitude higher gas response toward H2S. The enhanced sensitivity and selectivity toward H2S gas can be attributed to the formation of resistive p-CuO/n-SnO2 junction in nano-scale. [Copyright &y& Elsevier]

Abstract: Nanostructured CuO thin films were produced from alkaline baths containing saccharin as additive. X-ray diffraction analysis was used to determine the phase, crystallization and average crystallite size of the films. From the XRD analysis it was understood that the films have polycrystalline structure with monoclinic phases. The average crystallite size was also studied by the scanning electron microscopy. SEM images showed that the films were consisted of plate-like nanostructures with the thicknesses of ∼25nm. The effect of saccharin concentration on the transmission and optical band gap were also studied by UV–vis spectrophotometry. From the UV–vis spectra of the films it was seen that both the optical band gap and transmission properties of the films change with increasing saccharin concentration in the growth bath. [Copyright &y& Elsevier]

Abstract: In the present study, the proportion of nanofluid and dispersion of CuO nanoparticles in ethylene glycol (EG)–water mixture are considered. The effects of pH (in the constant temperature), weight percent of the nanoparticles, and the temperature are also studied. The zeta potential, absorbance and thermal conductivity are measured using a Malvern ZS Nano S analyzer, the UV–visible Spectroscopy, and the Transient Hot Wire (THW) methods. Moreover, in order to investigate the dispersion behavior, the heat transfer enhancement of the nanofluid and the thermal properties of the CuO nanoparticles are measured. Of course, the rate of the obtained thermal conductivity is in the 20–95°C range. The results show that CuO nanoparticles have a significant thermal effect on the mixture. In the optimum pH 7.8, the nanofluid has a maximum zeta potential and a maximum absorbance that can lead to a more stable state. Furthermore, in this optimum pH, the percent of optimum weight and the thermal conductivity enhancement (at 25°C) are 0.045 and 1.55, respectively. Also, the optimum thermal conductivity enhancement at 70°C is 1.66. [Copyright &y& Elsevier]

Abstract: In this piece of research we have used precipitation method to synthesize CuO nanoparticles. To investigate the characteristics of the CuO nanoparticles, particle size analyzer (PSA), X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and UV–visible absorption spectroscopy were used. To produce nanoparticles with uniform size, we optimized experimental conditions such as the temperature which was set at 78°C. The results showed that the synthesized CuO nanoparticles have a suitable dispersion and a thin-size distribution. Also based on the results, the average size of the nanoparticles was about 4nm, CuO nanoparticles with various shapes such as clews-like, nanowire, and stretched nanowire-shaped were synthesized by different reaction temperatures along with controlled addition of NaOH, and the surface area was obtained by the BET adsorption method. The maximum surface area obtained was 143.7m2/g which is a considerable surface area. [Copyright &y& Elsevier]

Abstract: CuO nanowires were prepared using Cu foil as substrate via a solution route in large scales. The method was simple, low cost, and can be completed in the absence of any surfactant. The morphological investigation of synthesized CuO products was analyzed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) which confirmed that the synthesized products are wire-shaped and are grown in large quantity. The detailed structural, compositional and optical characterizations of the synthesized nanowires were characterized by X-ray diffraction (XRD) pattern, Fourier transform infrared (FTIR) and UV–vis spectroscopy, which confirmed that the obtained nanowires were well-crystalline pure CuO and possessing good optical properties. Additionally, photocatalytic performance of the CuO nanowires was evaluated. About 90% of the methyl orange was degraded after 180min under nature light, which was significantly more efficient than CuO nanoparticles. [Copyright &y& Elsevier]

Abstract: Spongy CuO was successfully synthesized via direct pyrolysis of Cu3(btc)2 (btc=benzene-1,3,5-tricarboxylate) microporous metal-organic framework (MOF) in a horizontal tube furnace in the air, in which the Cu3(btc)2 was used as the Cu source and complexing molecule precursor. The as-prepared products were characterized by a series of techniques including XRD, SEM, EDX, TEM, and SAED. Results from SEM showed that the as-prepared spongy CuO with average diameter altering from 10 to 20μm consists of nanosheets with average edge length in the range of 80–200nm and thickness of about 30nm, which was also confirmed by TEM analysis. The XRD and SAED results showed that a purity phase of CuO was obtained after pyrolysis. It was also found that the reaction temperature played a key role in the formation of spongy CuO microstructures. The spongy material could be found potential application in various fields such as catalysis, absorption, and gas sensing. [ABSTRACT FROM AUTHOR]

Abstract: The rod-like and dandelion-like CuO nanomaterials have been prepared by the decomposition of a copper complex [Cu(pbbt)Cl2]2·CH3OH (pbbt=1,1′-(1,3-propylene)-bis-1H-benzotriazole) in the presence of suitable surfactants and alkalies under hydrothermal conditions. The CuO nanorods are about 50nm in diameter and up to 500–700nm in length; the average diameter of the dandelion-like CuO microspheres is of 2μm. A formation mechanism for the CuO nanomaterial was proposed. The gas-sensing properties of as-prepared CuO nanomaterial were studied. The sensitivity of the as-prepared CuO nanorods was better than that of dandelion-like CuO particles, and the CuO nanorods displayed special sensitivity to alcohol. [Copyright &y& Elsevier]

Abstract: The Cu4SO4(OH)6 was synthesized by a simple hydrothermal reaction with a yield of ~90%. Using Cu4SO4(OH)6 as the starting material, novel fishbone-like Cu(OH)2 was produced by a direct reaction of Cu4SO4(OH)6 with NaOH solution. The Cu(OH)2 consists of many needle-like nanorods parallel to each other and perpendicular to the direction of backbone, forming fishbone-like structure. Using the fishbone-like Cu(OH)2 as the sacrificial precursor, CuO with similar size and morphology was obtained through a simple heat treatment. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, X-ray photoelectron spectroscopy, BET nitrogen adsorption, and UV–Vis absorption spectroscopy were employed to characterize the as-prepared samples. The conversion of the Cu4SO4(OH)6 to the fishbone-like Cu(OH)2 was visualized by time-dependent SEM images. A mechanism was also proposed based on the observed results. [Copyright &y& Elsevier]

Two processes of dispersing CuO nanoparticles in n-alkanes by using the dispersant of oleic acid (OA) and sodium oleate (SOA) are compared in this investigation. The adsorption behavior and dispersion ability of OA and SOA are analyzed by estimating the zeta-potential, infrared spectroscopy (IR) and the sedimentation experiments. It is demonstrated that the dispersion process with SOA has more adsorptions of oleate on CuO nanoparticles than OA does, thus the prepared organic suspensions from SOA-modified CuO nanoparticles are much more stable. Moreover, the effects of molecular weight of alkanes on the suspension stability have also been clarified. [Copyright &y& Elsevier]

Highly dispersed copper oxide (CuO) nanoparticles with an average size of 6 nm have been successfully prepared by a novel quick-precipitation method. The as-prepared CuO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Visible absorption spectroscopy and BET nitrogen adsorption. The results show that the as-prepared CuO nanoparticles have high dispersion and narrow size distribution. The influence of reaction conditions on morphology of CuO nanocrystals was discussed. Spherical, ellipsoidal and needle-shaped CuO nanocrystals can be obtained simply by varying the reaction temperature and controlling the addition of NaOH. [Copyright &y& Elsevier]

ZnS:Cu nanocrystals are prepared by solution synthesis technique, and the optimum range of synthesis temperature and the particle size/shape for the high photoluminescence (PL) properties of ZnS:Cu nanocrystals are investigated in this study. With an increase of synthesis temperature, the crystal structure is not changed. However, the particle size increases slightly. PL intensity is maximum for the sample prepared at 85 °C for the temperature range used in this study (70–95 °C). This is the first observation for the ZnS:Cu nanocrystals prepared by solution synthesis technique. The X-ray photoelectron spectroscopy (Cu2p3/2), performed to explain this phenomenon, demonstrates that with lower synthesis temperature (<85 °C), Cu acts as the normal accepter dopant, leading to the high PL intensity. With higher temperature (>90 °C), however, Cu is transformed into CuO, and CuO acts as the nonradiative recombination center, resulting in the substantial decrease of PL intensity observed in this study. [Copyright &y& Elsevier]

Hierarchically branched ZnO/CuO film was fabricated by a two-step chemical process on Cu foil. CuO nanowires were firstly synthesized on Cu foil by a simple wet chemical method, and then ZnO nanowires were grown on the CuO nanowire scaffold through a hydrothermal process. Comparing with CuO film, the photocurrent response and incident photon to electron conversion efficiency yielded by the hierarchically branched ZnO/CuO film are significantly enhanced under visible light irradiation, which can be attributed to the large contact area with the electrolyte and direct pathways for charge carrier collection. The hierarchical ZnO/CuO thin film could be a promising material for solar energy conversion. [ABSTRACT FROM AUTHOR]

Porous copper oxide nanostructures were synthesized by thermal decomposition of copper hydroxide acetate precursor. The precursor synthesized by a facile solution phase method presents a flower-like configuration, assembled from plate-like structures. CuO with porous features were obtained via thermal decomposition of the precursor, but morphology remains unchanged after the conversion. Under laser light irradiation, copper hydroxide acetate displays a phase transition to CuO as observed by the power dependent Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchical CuO hollow microspheres (2–3μm) have been successfully prepared via a facile hydrothermal process on a large scale by using cupric acetate as a reagent in the presence of polyvinylpyrrolidone. The hollow sphere composed by many nanorods with wall thickness of 400nm. The surface area of the hollow CuO microspheres measured by a BET-nitrogen adsorption method is 25.7m2/g. It is also found that such unique hierarchical architecture shows excellent electrochemical performance for lithium ion batteries. [Copyright &y& Elsevier]

Abstract: Cupric oxide (CuO) nanostructures having different morphologies such as needle-like leaf, nanowire, cluster-like and microbundle of nanorods have been successfully synthesized via an environment-friendly ionothermal method using ionic liquids [BMIM]Br and [OMIM]Br in different temperatures at ambient pressure. The structure and the optical properties of the these CuO particles are investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible absorption spectroscopy. The results indicate that ionic liquids and temperature play an important role in size and morphology of the CuO nanostructures. A possible mechanism was proposed to explain the formation of CuO nanostructures with different morphologies. The band gaps are estimated to be 1.57–1.75eV according to the results of the optical measurements of the CuO nanostructures. [Copyright &y& Elsevier]

[Display omitted] • Facile preparation of mesoporous cauliflower-like CuO/Cu(OH) 2 structures. • CuO/Cu(OH) 2 significantly accelerates the decomposition process of AP. • 3 wt% CuO/Cu(OH) 2 lowers the HTD of AP by 96 °C, enhancing the heat release by 38.6%. • 3 wt% CuO/Cu(OH) 2 decreases the E a of AP decomposition to 65.2 ± 0.6 kJ mol−1. Nanostructured CuO-based materials are promising catalysts in the thermal decomposition of ammonium perchlorate (AP). Here, a facile ammonia-evaporation-induced fabrication of novel mesoporous nanoparticles-aggregated cauliflower-like CuO/Cu(OH) 2 structures is reported. The influence of the as-prepared material on AP decomposition was analyzed by TG and DSC and the results revealed its excellent catalytic performance. Adding 3 wt% CuO/Cu(OH) 2 to AP decreases the decomposition temperature by 96 °C, reduces the activation energy from 86 ± 4 kJ mol−1 to 65.2 ± 0.6 kJ mol−1 and increases the total heat release by 38.6%. Such catalytic activity approaches or exceeds those of the best performing CuO-based catalysts, making CuO/Cu(OH) 2 a strong candidate for use in catalyzed thermal decomposition of AP. [ABSTRACT FROM AUTHOR]

• ZnO, Cu doped ZnO, and CuO particles with 2D morphology was successfully synthetized by solvothermal method. • The doping process was successfully for 2 wt% Cu content. • For dopants from 6 to 50 wt%, there is CuO with rods shape. • For all Cu quantity incorporation presents a systematic widening in UV–Vis-NIR band absorption. ZnO, Cu doped ZnO, and CuO were synthesized by solvothermal method. Pure ZnO and CuO show two-dimensional (2D) particles with flake-like shape morphology and well-defined crystalline phases. The Cu incorporation slightly modifies the ZnO particle shape and size for low dopant. However, ZnO/CuO composite presents the co-existing morphologies with flake-like and small-rods shapes. The visible‐light absorption increases, directly proportional to the Cu content. However, ZnO/CuO composite shows wide ultraviolet–visible absorption between 200 and 1000 nm. The bandgap energy determined was 3.22 and 1.45 eV for ZnO and CuO, respectively. [ABSTRACT FROM AUTHOR]

• The CuO highly improved the absorption ability in visible light region. • Doping Al into Bi 2 Ga 4 O 9 presented high photo-oxidation activity and low cost. • The BGAO-2.5%Cu exhibited the highest photo-oxidation activity. • The photo-generated hole played a main role for the RhB degradation. Herein, we present a systematic investigation of CuO nanoparticles decorated on Bi 2 Ga 2.8 Al 1.2 O 9 semiconducting photocatalyst for the photo-oxidation rhodamine B (RhB) under visible-light. Under the same condition, all cocatalysts (CuO, Ag, Au, Pt and Co) enhanced the photocatalytic activity than the intrinsic Bi 2 Ga 2.8 Al 1.2 O 9 photocatalyst, where the BGAO-2.5%Cu photocatalyst show the highest photo-oxidation activity. The kinetic constant (k) of the obtained optimal photocatalyst is 3.9 and 5.7 times than those of Bi 2 Ga 2.8 Al 1.2 O 9 and Bi 2 Ga 4 O 9 semiconductors, respectively. The photo-oxidation efficiency of RhB is 99.14% over the optimal photocatalyst in 2 h. The possible photocatalytic mechanism of the function of CuO on the semiconductor is proposed. This work highlight the CuO which was decorated on semiconductor by a simple photodeposition method play an essential role for the environmental cleaning. [ABSTRACT FROM AUTHOR]

Abstract: This study describes that CuO nanowires were synthesized by heating copper powder in air. CuO nanowires can grow on the surface of the spherical CuO/Cu2O. The samples were heated in the air within the temperature range from 300°C to 700°C. The diameter and density of nanowires can be controlled by the heating temperature and time. The products were examined by XRD, SEM and TEM. The morphology, composition, and crystal structure show that the single crystalline CuO nanowires can be synthesized on the surface of the spherical CuO/Cu2O and CuO was the only product when the sample was heated at the temperature of 500°C and higher. [Copyright &y& Elsevier]

Abstract: In this work, the authors present a method for the fabrication of a sensitive and relatively selective YSZ-based NO2 gas sensor utilising a CuO sensing electrode (SE). The SE was fabricated using heat-treated copper hydroxide, which was formed from the combination of an aqueous copper nitrate with a basic solution, via a highly controlled syringe-pump synthesis technique. After calcination, the resulting CuO was observed to be comprised of large adjoining micro-dimensional particles, with highly stepped edges. The developed sensor was sensitive to NO2, and relatively insensitive towards several common automotive exhaust components including CO, CH4, C3H6, C3H8, NO, H2, and NH3 at an operational temperature of 550°C, under humid conditions. [Copyright &y& Elsevier]