Gotowa bibliografia na temat „Copper hydroxide nanostructures”

Abstract This study displays the facile and fluent electrochemical determination of uric acid (UA) through exceptional copper oxide nanostructures (CuO), as an effective sensing probe. The copper oxide nanostructures were fabricated via an aqueous chemical growth method using sodium hydroxide as a reducing agent, which massively hold hydroxide source. Copper oxide nanostructures showed astonishing electrocatalytic behavior in the detection of UA. Different characterization techniques such as XRD, FESEM, and EDS were exploited to determine crystalline nature, morphologies, and elemental composition of synthesized nanostructures. The cyclic voltammetry (CV) was subjected to investigate the electrochemical performance of UA using copper oxide nanostructures modified glassy carbon electrode CuO/GCE. The CV parameters were optimized at a scan rate of 50 mV/s with −0.7 to 0.9 potential range, and the UA response was investigated at 0.4 mV. PBS buffer of pH 7.4 was exploited as a supporting electrolyte. The linear dynamic range for UA was 0.001–351 mM with a very low limit of detection observed as 0.6 µM. The proposed sensor was successfully applied in urine samples for the detection of UA with improved sensitivity and selectivity.

A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make highly mesoporous metal oxide nanostructures of manganese and copper, and hydroxide nanostructures of magnesium.

Cupric oxide (CuO), having a narrow bandgap of 1.2 eV and a variety of chemophysical properties, is recently attractive in many fields such as energy conversion, optoelectronic devices, and catalyst. Compared with bulk material, the advanced properties of CuO nanostructures have been demonstrated; however, the fact that these materials cannot yet be produced in large scale is an obstacle to realize the potential applications of this material. In this respect, chemical methods seem to be efficient synthesis processes which yield not only large quantities but also high quality and advanced material properties. In this paper, the effect of some general factors on the morphology and properties of CuO nanomaterials prepared by solution methods will be overviewed. In terms of advanced nanostructure synthesis, microwave method in which copper hydroxide nanostructures are produced in the precursor solution and sequentially transformed by microwave into CuO may be considered as a promising method to explore in the near future. This method produces not only large quantities of nanoproducts in a short reaction time of several minutes, but also high quality materials with advanced properties. A brief review on some unique properties and applications of CuO nanostructures will be also presented.

Electric field enhanced approach has been used to synthesize different copper hydroxide morphologies as high-performance supercapacitors electrode materials. Employing this efficient, simple and low cost method, various shapes such as rod, flower and cube with an average grain size of 30[Formula: see text]nm to 1[Formula: see text][Formula: see text]m were obtained on the copper substrate. The results revealed that applied electric field considerably accelerates the formation time of nanostructures from several days to close to 1[Formula: see text]min, where some of the desired nanostructures were obtained even in 1[Formula: see text]s. The electrochemical properties of different morphologies were compared using cyclic voltammograms and charge/discharge tests and electrochemical impedance spectroscopy. The obtained results demonstrated that the two types of fabricated structures showed high maximum areal and specific capacitance of 42[Formula: see text]mF/cm2 and 178[Formula: see text]F/g at scan rate of 20[Formula: see text]mVs[Formula: see text], respectively, which make them excellent and promising electrode materials for supercapacitors.

CuO nanoparticles were synthesized in two different ways, firstly by precipitation method using copper acetate monohydrate Cu(CO2CH13)2·H2O, glacial acetic acid (CH3COOH) and sodium hydroxide(NaOH), and secondly by sol-gel method using copper chloride(CuCl2), sodium hydroxide (NaOH) and ethanol (C2H6O). Results of scanning electron microscopy (SEM) showed that different CuO nanostructures (spherical and Reef) can be formed using precipitation and sol- gel process, respectively, at which the particle size was found to be less than 2 µm. X-ray diffraction (XRD)manifested that the pure synthesized powder has no inclusions that may exist during preparations. XRD results showed the particles size of highest peak at 38.9°, was equal to (15.93nm). In addition, Fourier transform infrared spectroscopy (FT-IR) were used to describe the prepared CuO nanostructures absorption peak at 610 cm-1 which confirms that the synthesized product is a pure CuO and may be attributed to Cu2O infrared active mode.

Flower-like CuO nanostructures have been prepared via cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. Here, CuCl2•2H2O was used as copper raw material, and sodium hydroxide was used as precipitate. The resulting CuO powders were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). X-ray diffraction (XRD) pattern exhibited the nanocrystalline nature with monoclinic structure for the as-synthesized nanostructures. FESEM images indicated that the flower-like CuO nanostructures are composed of many interconnected nanosheets in size of several micrometers in length and width and 60-80 nm in thickness. The possible formation mechanism of flower-like CuO nanostructures was discussed.

Abstract Glucose electrochemical sensors based on nanostructures of CuO/Cu(OH)2 onto graphene paper were prepared by thermal (solid) and nanosecond pulsed laser (molten phase) dewetting of a CuO layer 6 nm thin deposited by sputtering. Dewetted systems, obtained without the use of any binder, act as array of nanoelectrodes. Solid state and molten phase dewetting produce nanostructures of copper oxide-hydroxide with different average size, shape and surface composition. Molten phase dewetting originates particles with size below 100 nm, while solid state dewetting produces particles with average size of about 200 nm. Moreover, molten phase dewetting produce drop-shaped nanostructures, conversely nanostructures derived from solid state dewetting are multifaceted. X-ray photoelectron spectroscopy (XPS) characterization revealed that the surface of nanostructures is formed by a copper(II) species CuO and Cu(OH)2. Shape of anodic branch of the cyclic voltammograms of glucose in alkali solution evidenced a convergent diffusion mechanism. Analytical performances in amperometric mode are as good as or better than other sensors based on copper oxide. Amperometric detection of glucose was done at potential as low as 0.4 V versus saturated calomel electrode by both types of electrodes. Linear range from 50 μM to 10 mM, sensitivity ranging from 7 to 43 μA cm−2 mM−1 and detection limit of 7 μM was obtained. Good analytical performances were obtained by laser dewetted electrodes with a low copper content up to 1.2 by atoms percentage of the surface. Analytical performance of the proposed electrodes is compliant for the determination of glucose both in blood serum, saliva or tear.

The necessity of providing clean water sources increases the demand to develop catalytic systems for water treatment. Good pollutants adsorbers are a key ingredient, and CuO is one of the candidate materials for this task. Among the different approaches for CuO synthesis, precipitation out of aqueous solutions is a leading candidate due to the facile synthesis, high yield, sustainability, and the reported shape control by adjustment of the counter anions. We harness this effect to investigate the formation of copper oxide-based 3D structures. Specifically, the counter anion (chloride, nitrate, and acetate) affects the formation of copper-based hydroxides and the final structure following their conversion into copper oxide nanostructures over porous templates. The formation of a 3D structure is obtained when copper chloride or nitrate reacts with a Sorites scaffold (marine-based calcium carbonate template) without external hydroxide addition. The transformation into copper oxides occurs after calcination or reduction of the obtained Cu2(OH)3X (X = Cl− or NO3−) while preserving the porous morphology. Finally, the formed Sorites@CuO structure is examined for water treatment to remove heavy metal cations and degrade organic contaminant molecules.

Bacterial antibiotic resistance is becoming wide spread due to the excessive and unregulated use of antibiotics in healthcare and agriculture. At the same time the development of new antibiotics has become slow. Adding antibiotics to surfaces result in poor long-term performance in preventing bacterial build-up. This also increases the risk of development of more drug resistant strains. Hence, approaches for realising antibacterial action through physical surface topography have become increasingly important and interesting to the community in recent years. The complex and strain dependent nature of the bacterial cell wall interactions with nanostructured surfaces leads to many challenges while the design of nanostructured antibacterial surfaces is concerned. First part of this work focuses on enhancing the antibacterial activity of the nanostructured surfaces by coating them with different chemistries. Using two different categories of coatings firstly metals (Cu and Ag) and secondly biocompatible polymer chitosan, we demonstrate efficient bactericidal activity against a range of bacteria. The second part of the work focuses on developing processing technology for demonstration of such nanostructured antibacterial surfaces for practical applications. The focus was to demonstrate a low-cost processing technology which can be easily scaled to large area. Finally, we test the bactericidal efficacy of the developed surfaces against the drug resistant strains obtained from a hospital. In nature several insects such as cicada wing, dragonfly wing, dronefly wing possess sharp nanostructures on their wing which kill bacteria by contact killing mechanism. When a bacterium sits on such surfaces, they get stretched and deformed while trying to settle on maximum anchoring points. When the threshold of stretching is reached, cell wall is compromised, and cell lysis takes place. In this work a range of surfaces with distinct surface topography and chemistry has been studied. Initially, inspired from dragonfly wing, high-aspect ratio silicon nanostructured surface (NSS) was fabricated using a single-step deep reactive ion etching (DRIE) technique. The nanostructures were found to be random in both size (300-1100 nm) and spatial distribution (300-500 nm). Post fabrication the surfaces were coated with a thin layer of copper (NSS_Cu) and silver (NSS_Ag). The bactericidal efficacy of the NSS_Cu, NSS_Ag and NSS surfaces were tested and compared against Gram-negative bacterium E. coli. NSS_Cu was found to have the highest bactericidal efficacy killing 97% of the bacteria in just 90 minutes. The results from this study suggests that the addition of a surface chemistry to the physical nanostructures enhances the bactericidal efficacy. However, copper is not stable when exposed to environment and oxidises to form CuO, Cu2O etc. To overcome this problem, we replaced copper with a stable biocompatible polymer “Chitosan (CHI)”. Unlike copper coating where sputtering tool was used, CHI can be coated on any substrate by a simple dip coating technique making the process simpler and cost-effective. CHI was coated on flat silicon (Si_CHI) and NSS surfaces (NSS_CHI). The bactericidal efficacy of the surfaces was tested against Gram-negative E. coli and Gram-positive S. aureus. NSS_CHI surface was found to be the most efficient in killing bacteria as compared to the Si_CHI and NSS surfaces. Also, the antibiofilm characteristics of these surfaces was studied. NSS_CHI surface was found to have the least amount of bacterial bio mass on its surface after a period of 5 days of bacterial incubation in Luria Broth (LB) medium for both E. coli and S. ii aureus. Also, the CHI coating was found to be very stable when exposed to PBS for 7 days showing its durability for a longer period. CHI coating was cost-effective and easy as compared to the sputtering technique. However, fabrication of NSS using DRIE still comes with a cost. To overcome this issue, we fabricated ZnO nanostructured surface using simple chemical synthesis method at near room temperature (~20O C). Neither sophisticated tool like DRIE nor clean room environment was required for this process. Sharp ZnO nanostructured surface was fabricated in an alkaline solution containing zinc nitrate hexahydrate and potassium hydroxide. The synthesis time was set to 12 hours (h). The ZnO nanostructures possess a length of 1.5-2 𝜇m, tip diameter ~20 nm, tip angle ~ 10O. Also, this technique was used to grow the ZnO nanostructures on a variety of substrates such as copper sheet, glass, polydimethylsiloxane (PDMS) showing the versatility of the fabrication technique. The antibacterial performance of the ZnO nanostructured surface was evaluated against Gram-negative E. coli. Flat silicon surface and silicon surface coated with 20 nm of ZnO thin film were taken as controls. Bacterial attachment was seen on the flat silicon and flat ZnO substrates after a 24 h of incubation. In contrary no bacterial colony was observed on the nanostructured ZnO surface showing its bacteriophobic behaviour. The simplicity and cost effectiveness of this process makes it possible for this surface to be used in practical applications. Also, large scale fabrication is possible using this technique. Despite several advances in this area, it is well understood that the micro/nano structures are mechanically fragile. This reduces their reliability and hence increases the cost of use. Moreover, several applications such as aprons, gloves, temporary mats etc. require these surfaces to be flexible. The above requirements call for the development of flexible antibacterial surfaces with mechanical reliability. In addition, the surfaces should be low-cost so that they can be periodically replaced to address the issues with reliability. To achieve this, transferring of copper hydroxide nanostructures onto a curable silicone polymer, polydimethylsiloxane (PDMS), was carried out by a two-step process: (i) copper etching to form nanostructures and (ii) transfer of the copper based nanostructures onto the PDMS surface by mechanical tearing. This PDMS surface decorated with the copper nanostructures (PDMS_Cu) is unique in displaying two functionalities; superhydrophobicity preventing bacterial adhesion and a potent bactericidal effect from the copper nanowires as copper has been regarded as a very good antimicrobial agent from centuries. This process was scaled for large area fabrication for real world applications. Absence of a micro-fabricated template makes this process significantly cheaper and easily scalable as it is not limited by the size of the template. In addition, as the cured polymer strongly holds these nanowires in place, these surfaces showed reliability against abrasion, tape peel and solid weight impact. Also, the surface was superhydrophobic after dry heat, moist heat and UV exposure. The fabricated PDMS_Cu surface was tested against drug resistant E. coli, S. aureus and K. pneumoniae. The surface exhibited excellent antibacterial behaviour against all the drug resistant bacteria. Also, the PDMS_Cu surfaces were kept at several infectious places in the hospital. The flora count on the PDMS_Cu was lesser than the control surfaces showing its superior antibacterial property. The ability of the PDMS_Cu surface to support RAW Macrophage and HeLA cells proliferation was also evaluated using confocal microscopy by staining the cells with DAPI and tubulin. Both the Macrophage and HeLa cells attachment was found to be higher on the coverslip and PDMS substrates as compared to the PDMS_Cu surface which can be attributed to the superhydrophobic property of the PDMS_Cu iii surface. MTT assay method was also used to assess the cell metabolic activity. ~50% RAW macrophage and ~71% HeLa cells were found to be viable after an incubation period of 5 h. Taken together, these data confirm that the PDMS_Cu surface was not cytotoxic to the RAW macrophage and the HeLa cells. To demonstrate its application in healthcare, heartbeat sound recording was carried out via the PDMS_Cu surface. Good quality heart beat sound was recorded showing its plausible use as a thin covering on the stethoscope diaphragm to prevent the transmission of pathogenic flora from one person to another in the hospital. Every surface studied in this work exhibits unique topography and surface chemistry and they can be used in several applications such as photovoltaic, high efficiency photo detector and sensors, water treatment, food packaging, health care etc.