Hierarchical CuO Nanostructures Research Articles

Ionic liquid dopant induced 3D hierarchical CuO nanostructures with doped heteroatoms and highly dispersed Ag for electrochemical upgrading of 5-hydroxymethylfurfural

The electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) has received increasing attention due to its carbon–neutral and value-added chemical properties, and the development of electrocatalyst with highly active and selective is crucial. Highly dispersing metal atoms throughout the catalyst can maximize the catalytic efficiency. Here, we synthesized a 3D hierarchical CuO nanostructure induced by ionic liquid with heteroatoms doping and Ag dispersing (Ag-CuO@IL), and this self-supported catalyst can reach 10 mA cm−2 at only 1.33 V vs RHE and achieved HMF conversion of 98.5 %, FDCA yield of 97.1 % and Faraday efficiency of 92.2 %. The excellent catalytic performance of Ag-CuO@IL for HMFOR is attributed to the doped heteroatoms derived from ILs to promote electron redistribution and the generated oxygen vacancies induced by IL anions to highly disperse Ag. Also, the catalyst was the nanosheet-assembled spherical clusters with 3D nanostructure, which exposed a large number of active sites. Density functional theory calculations showed that Ag-CuO@IL possessed moderate adsorption strengths of HMF and OH–, thus facilitating the desorption of the products in the reaction process. The design that induced by ionic liquid dopant not only provides an effective and green mean for HMFOR, but also has the large potential to guide the synthesis of other catalysts with improved performances in various applications.

Leaf-like copper oxide mesocrystals by collagen-assisted biomineralization show attractive biofunctional and electrochemical properties

A robust one-pot strategy based on collagen-templated biomineralization has been developed to create hierarchical CuO nanostructures with a good electrochemical performance.

A novel route for the preparation of self-assembled CuO hierarchical nanostructures by hydrothermal processing at high pressure

Self-assembled CuO hierarchical nanostructures were synthesized via the hydrothermal reaction of Cu9S5 microcrystals with NH3 in presence of O2 at high-pressure (3.5 MPa). It is shown that small molecules such as NH3 may serve as templates for the development of different sphere-like hierarchical nanostructures, such as self-assembled nanosheets (at 3 h of reaction) and self-assembled nanofibers (at 12 h of reaction). Confinement effects in the hierarchical nanofibers were confirmed by Raman and UV–vis spectroscopy. Additionally, we show that the hierarchical nanofibers exhibited higher solar photocatalytic activity for the degradation of methylene blue.

Facile preparation of hierarchical CuO nanostructures as a integrate binder-free anode for high-performance lithium-ion batteries

Novel CuO hybrid nanostructures composed of one-dimensional (ID) porous carbon nanofibers and two-dimensional (2D) graphene nanosheets have been fabricated with the help of electrospinning technique, which is denoted as CuO@PCNF/GN. The microstructure and morphology of the CuO@PCNF/GN were investigated by X-ray diffraction and transmission electron microscopy. The electrochemical performances of the as-prepared materials as a novel bind-free anode for lithium ion battery (LIB) were investigated. The CuO@PCNF/GN electrode exhibited high discharge capacity of 665 mAh g−1 after 60 cycles at the current density of 100 mA g−1. Even at 800 mA g−1, the discharge capacity of the anode could still maintained at 443 mAh g−1. The excellent electrochemical properties of CuO are greatly related to the unique 3D interconnected structure of continuous PCNF and GN, which enables efficient electron/ion transport and migrate the volume change of active CuO materials.

Hierarchical copper oxide as efficient enzymeless amperometric biosensor and promising photocatalyst

Thin films of hierarchical CuO nanostructures have been prepared. The synthesized material was thoroughly characterized with the help of advanced instrumentation techniques. The CuO modified FTO electrode, i.e. FTO/CuO was taken for amperometric glucose sensing as enzymatic mimic that came out with excellent result with a notably low detection limit of 0.0084 mM. The notably high optical absorption in visible region also makes the material a good candidate to capture visible photons and facilitate photocatalysis of some non-biodegradable organic chemicals like Rhodamine B, Methylene Blue and Congo Red with a faster and better kinetics than many previous reports. The hierarchical structure allows good interaction between the greatly exposed surfaces and facilitates the amperometric sensing and photochemical performances. The estimation of total organic carbon (TOC) content also strengthens the photocatalytic attributes of the synthesized material.

Green synthesis of CuO nanostructures with bactericidal activities using Simarouba glauca leaf extract

For the first time, copper oxide (CuO) nanostructures were synthesized through a new green route using the leaf extract of S. glauca and characterized. The XRD pattern of CuO disclosed diffraction peaks correspond to monoclinic crystal structured CuO. The SEM and HR-TEM images demonstrated the presence of CuO nanostructures. The detected Cu and O elements through the EDAX analysis reveal the pristine nature of the hierarchical CuO nanostructures. Hence, this work complete that the potential bactericidal activity exhibited by CuO nanostructures against Gram negative E. coli (MTCC 1698) bacterial strain with zone of inhibition of 28 mm.

Enhanced lithium storage performance of hierarchical CuO nanomaterials with surface fractal characteristics

Self-assembled hierarchical CuO nanostructures with fractal structures were prepared by a mild method and exhibited excellent lithium storage properties, certain of which even demonstrated a high reversible capacity of 827 mAh g−1 at a rate of 0.1 C. An interesting phenomenon was observed that the electrochemical performance varies along with the structure complexity, and the products with higher surface factal dimensions exhibited larger capability and better cyclability. Structural and electrochemical analysis methods were used to explore the lithiation kinetics of the samples and the reasons for the outstanding electrochemical performances related to the complexities of hierarchical nanostructures and the irregularities of surface and mass distribution.

HEPES-mediated controllable synthesis of hierarchical CuO nanostructures and their analogous photo-Fenton and antibacterial performance

Owing to the strongly morphology and size-dependent properties of nanomaterials, developing a simple and eco-friendly approach for controlling synthesis and assembly of hierarchical CuO nanostructures plays a critical role. In this work, we successfully developed an eco-friendly and facile hydrothermal route for controllable synthesis of various morphologies CuO nanostructures, where traditional and toxic additives were replaced by biocompatible 4-(2-hydroxyethyl)-1-piperazineethane-sulfonic acid (HEPES). The growth rate and orientation of CuO nanoparticles were tuned through adjusting the concentration and pH value of HEPES. The XRD pattern, SEM, UV-DRS, and BET indicated CuO nanostructures maintained high purity and excellent crystalline nature and showed more regular morphology and size with enhanced visible light absorption. The analogous photo-Fenton assay demonstrated that the as-prepared CuO nanostructures present enhanced dye removal capability when compared with CuO synthesized in pure water. Furthermore, the antibacterial assay on S. aureus was also investigated, and CuO nanoparticles with smallest size displayed the best antibacterial performance. These results reveal that HEPES shows a remarkable influence on the possible application of as-prepared CuO nanostructures which having great potential in pollutant removal.

Design and construction of three-dimensional flower-like CuO hierarchical nanostructures on copper foam for high performance supercapacitor

We have developed a simple and cost-effective one-step surface oxidation method to synthesize three-dimensional (3D) flower-like, similar to that of a blooming chrysanthemum, CuO hierarchical nanostructures directly on a copper foam, which is acting as the Cu source and the current collector. The as-prepared sample can be directly used as a binder-free electrode for supercapacitors. Benefiting from the novel synthesis strategy and the 3D connect/quasi-connect structures, the as-prepared CuO/copper foam electrode can provide massive active sites for redox reactions, high electronic conductivity, short diffusion pathway for ions and effectively electrolyte penetrating. These characteristics together with the synergy effect between CuO and copper foam substrate lead to a high capacitance of 1641.4mFcm−2, good rate capability (77.2% retention upon increasing the current density by 10 times) and good cyclability (79% retention after 10000 cycles). These results suggest that the CuO electrode demonstrates a good potential for high performance energy storage devices.

Carnation‐like CuO Hierarchical Nanostructures Assembled by Porous Nanosheets for Nonenzymatic Glucose Sensing

AbstractCarnation‐like CuO hierarchical nanostructures assembled by ultrathin porous nanosheets were successfully fabricated via a facile solvothermal route followed with heat treatment. As‐prepared CuO nanostructures exhibited excellent catalytic activity toward glucose oxidation in the absence of any enzymes. Under the optimized conditions, the CuO‐based enzymeless glucose sensor showed high sensitivity of 3.15 mA mM−1 cm−2, low limit of detection (98 nM, S/N=3), good reproducibility, excellent selectivity and long‐time stability. The superb nonenzymatic glucose sensing performance of the CuO hierarchical nanostructures was attributed to the highly catalytically active sites at the edges and basal planes of the CuO nanosheets, facile transportation of analytes through the abundant mesopores and macropores, robust and stable hierarchical structure. Moreover, the CuO‐based enzymeless glucose sensor showed high accuracy and reliability in comparison with clinical glucometer for quantitative determination of glucose in human blood serum samples.

Morphological tuning of CuO nanostructures by simple preparative parameters in SILAR method and their consequent effect on supercapacitors

Morphology-controlled synthesis of nanomaterials by tuning simple preparative parameters is an impressive path to develop diverse nanostructured materials. Here, we are exploring a successful example of fabrication of hierarchical CuO nanostructures (nanoflakes, nanopetals and diffused nanorods) by simply controlling temperature of reaction bath (3rd beaker) in SILAR method. These CuO nanostructures are further successfully employed as electrode material in supercapacitors. The correlation between electrochemical supercapacitive properties and nanostructures of CuO is investigated in detail. It is revealed that, the supercapacitive properties strongly depend on CuO nanostructures. The specific capacitance values for nanoflakes, nanopetals and diffused nanorods of CuO are found to be 664 F/g, 790 F/g and 695 F/g, respectively at 5 mV/s scan rate. Ragone plot ascertains that CuO nanostructures obtained by SILAR method are potential candidates for high power and high energy density supercapacitors. In addition, EIS analyses show lower ESR values and excellent frequency response for CuO nanostructures.

Synthesis of flower-like cuo hierarchical nanostructures as an electrochemical platform for glucose sensing

Flower-like CuO hierarchical nanostructures were synthesized on copper foil substrate through a simple wet chemical route in alkaline media at room temperature. SEM images collected at different reaction times revealed the transformation of initially formed Cu(OH)2 nanowires to flower-like CuO nanostructures. The hierarchical structure of the as-prepared CuO showed high electrocatalytic activity towards the oxidation of glucose making it a promising electrode material for the development of non-enzymatic glucose sensor. The amperometric sensor exhibited a wide linear response to glucose ranging from 4.5 × 10−5 to 1.3 × 10−3 mol L−1 (R2 = 0.99317) at fixed potential of 0.3 V. The detection limit was 6.9 × 10−6 mol L−1 (LOD = 3σ/s) with a sensitivity of 1.71 μA μmol−1 cm−2. Moreover, the developed sensor offers a fast amperometric response, good selectivity and stability.

Formation of Hierarchical CuO Nanostructures on Copper Foil by Chemical Bath Deposition for Applications in Superhydrophobic Surfaces

Hierarchical CuO nanostructures (urchin-like and grassy island structure) were successfully synthesized by a simple chemical bath deposition method at low temperature of 70°C in a short reaction time of 1h. XRD analysis revealed the presence of pure crystalline monoclinic CuO. Morphological analysis revealed the formation of spherical structures composed of numerous hair-like structures. The pH of the solution was also investigated to have a great effect on the morphology of the CuO nanostructures. At lower pH, the structures tend to form urchin-like structures; while at higher pH, the structures tend to form grass-like islands. A growth mechanism was also proposed in this paper. Lastly, wettability test proved the stable superhydrophobic property of the CuO nanostructured thin film surface.

Facile synthesis of Zn doped CuO hierarchical nanostructures: Structural, optical and antibacterial properties

ZnxCu1−xO (where x= 0, 0.01, 0.03, 0.05, 0.07 and 0.1 mol%) hierarchical nanostructures have been prepared via soft chemical route. X-ray diffraction (XRD) results of the synthesized samples reveal the monoclinic structure of CuO without any impurity related phases. The micro-structural parameters such as crystallite size and microstrain have been strongly influenced by Zn doping. Scanning electron microscope (SEM) analyses depict the formation of hierarchical nanostructures having average particle size in the range of 26-43 nm. The surface area of CuO nanostructures has been reduced systematically with the increase in Zn content which is linked with the variations in particle size. An obvious decrease in the optical band gap energy of the synthesized CuO hierarchical nanostructures has been observed with Zn doping which is assigned to the formation of shallow levels in the band gap of CuO and combined transition from oxygen 2p states to d sates of Cu and Zn ions. The bactericidal potency of the CuO hierarchical nanostructures have been found to be enhanced remarkably with Zn doping.

Facile fabrication of three-dimensional hierarchical CuO nanostructures with enhanced lithium storage capability

3D hierarchical CuO nanostructures with flower-like and urchin-like morphologies have been prepared by a solvothermal method. They display high discharge capacity, good rate capability and long cycle life as anode materials for lithium-ion battery.

Facile synthesis of hierarchical CuO nanostructures with enhanced photocatalytic activity

Herein we present a simple solution‐based protocol to produce a highly efficient photocatalyst consisting of a 3D assembly of 2D nanostructures via one‐pot synthesis. Such hierarchical assembly allow a very high surface/volume ratio and facing of active photocatalytic surface. Morphological and structural investigations of the as‐grown CuO nanostructures have been performed by FESEM, STEM, HRTEM, SAED and XRD analyses. A detailed study of the photocatalytic activity has been carried out, comparing CuO with reference TiO2 nanoparticles: a very high photocatalytic activity has been measured, higher than that of commercial TiO2 and among the best reported in literature for CuO. This can be reasonably ascribed to the synthetic procedure: on the one hand the hierarchical assembly exhibit a very high surface to volume ratio; on the other, the surfactant‐free approach allows the whole surface of the nanostructure to be exposed to the chemical environment and hence maximize the photo‐degradation of organic pollutants.

Enhancement in supercapacitive properties of CuO thin films due to the surfactant mediated morphological modulation

The complex hierarchical CuO nanostructures (woolen clumps, stacked nanosheets and nanobuds) have been developed through a chemical bath deposition method using surfactant assisted approach. The morphology of CuO nanostructures can be easily tuned using different surfactants as a soft chemical template. Nanobuds clusters deliver a superior 3D conductive framework, which allows well electrolytic accessible surface area and provides a shortest path for ions. The porous and well defined nanostructure renders a high contact surface area for the intercalation/deintercalation of ions into/out of active materials and reduces the path length for electrolyte ion transport. The maximum specific capacitance of 396Fg−1 at 5mVs−1 is calculated for CuO nanobuds structured electrode. Moreover, all the CuO nanostructures reveal better power performance, excellent rate as well as long term cycling stability. Such a study will encourage for the preparation of 3D nanostructures framework of the other materials using surfactant assisted approach.

Sonochemical synthesis and nonlinear optical property of CuO hierarchical superstructures

Carambolla-like CuO hierarchical nanostructures with diameter of about 200nm and length of 600nm have been successfully synthesized through a fast and facile sonochemical method. The morphology, crystallinity and size of the as-prepared products were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The growth mechanism of carambolla-like CuO nanostructures is discussed by monitoring different reaction times. It is shown that the carambolla-like CuO nanostructures are formed through oriented attachment of nanowires. In addition, the nonlinear optical property of carambolla-like CuO nanostructures has also been investigated, indicating that these nanomaterials have potential future application in nonlinear optics.

Growth, characterization and electrochemical properties of hierarchical CuO nanostructures for supercapacitor applications

In this paper, we have investigated the electrochemical properties of hierarchical CuO nanostructures for pseudo-supercapacitor device applications. Moreover, the CuO nanostructures were formed on Cu substrate by in situ crystallization process. The as-grown CuO nanostructures were characterized using X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR), X-ray photoelectron spectroscopy and field emission-scanning electron microscope (FE-SEM) analysis. The XRD and FT-IR analysis confirm the formation of monoclinic CuO nanostructures. FE-SEM analysis shows the formation of leave like hierarchical structures of CuO with high uniformity and controlled density. The electrochemical analysis such as cyclic voltammetry and electrochemical impedance spectroscopy studies confirms the pseudo-capacitive behavior of the CuO nanostructures. Our experimental results suggest that CuO nanostructures will create promising applications of CuO toward pseudo-supercapacitors.

Self-assembled synthesis of 3D CuO flocculus-like nanosheet-based hierarchical nanostructures

A simple, surfactant-free, and environmentally benign method has been developed to synthesize a novel 3D flocculus-like CuO hierarchical nanostructure self-assembled with 2D nanosheet as building blocks. Detailed proofs demonstrate that the overall synthetic process underwent the dehydration and re-crystallization of precursor Cu(OH)2 nanowires, and the subsequent two-step oriented attachment. In addition, 3D butterfly-like and flower-like CuO nanostructures consisted of 2D nanosheets could be obtained by adjusting the concentration of NaOH(cNaOH) in the solution. cNaOH played a key role in tailoring the thickness of the nanosheets and changing the morphology of the product. This report may be helpful to constructing fine-tune hierarchical CuO nanostructures under basic conditions.