Template Free Synthesis of Mesoporous CuO Nano Architects for Field Emission Applications (original) (raw)
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Journal of Solid State Chemistry, 2010
We report a simple method for growing photoluminescent mesoporous CuO nanoparticles by a chemical route, using the single precursor technique. The final products were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), N 2 adsorptiondesorption isotherm, UV-vis absorption spectroscopy, photoluminescence (PL) spectroscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and Hall measurements. Structural analysis reveals that the average pore diameter of the as-prepared CuO is about 38.8Å and it comes with an average surface area of 66.63 m 2 /g. N 2-sorption analysis shows that the resulting isotherm as type IV; which is the characteristic of mesoporous materials. The average crystal diameter, as derived from the XRD data analysis is found to be about 20 nm. FESEM measurement reveals that the material is composed of cubic nanoparticles. The UV-vis spectrum of the material shows significant amount of blue-shift in the band gap energy (E g), due to the quantum confinement effect exerted by the nanocrystals. The Raman study of the CuO nanostructures also indicates the high crystalline nature of the material. From the positive sign of Hall coefficient, the p-type conduction nature of the deposited film is established. The film was found to show high magnetoresistance, which is in the order of 10 5 O.
Room temperature growth and field emission characteristics of CuO nanostructures
Vacuum, 2017
A variety of CuO nanostructures have been synthesized directly on copper foils by room temperature oxidation of copper through wet chemical method. Alkaline condition necessary for the growth process was maintained by the application of NaOH and NH 3 precursors. pH of the solution and reaction time were selected as the process variables. Formation of CuO was confirmed by X-ray diffraction pattern analysis. Evolution of morphologies of the phases formed was characterized by field emission scanning electron microscopy, leading to elucidation of the growth mechanism. Different types of CuO nanostructures were observed to be formed at different process parameters, selected for the present study. Field emission characteristics of CuO nanorods and CuO nanoflakes were also investigated. Emission current density of CuO nanorods and CuO nanoflakes were determined to be 0.90 mA/cm 2 and 0.48 mA/ cm 2 , respectively. Huge difference in the emission current density indicates that field emission properties of CuO nanostructures are strongly affected by their morphology.
Chemically activated growth of CuO nanostructures for flexible cold cathode emission
A generalized protocol for solution-based seeding and self-assembly of a wide range of cupric oxide (CuO) nanostructures is developed. Parameters of KMnO 4 activation are found to play a crucial role in chemical seeding and vis-à-vis in evolution of various morphologies. To demonstrate the devised two-stage seeding and self-assembly protocol, various types of CuO nanostructure films are fabricated on flexible carbon fabric. Such systems are found to retain the native substrate's innate flexibility and the structural integrity of the grown nanostructures showed no deterioration upon rolling up or even twisting to a large degree. Among the various CuO morphologies, the nanoneedles exhibited excellent field-emitting traits such as a lower turn-on field of 0.9 V μm −1 and an appreciably good current density of 1.65 mA cm −2 at an applied macroscopic field of 1.25 V μm −1 as well as high stability under large applied fields. Theoretical estimation of the local electric field distribution supported the experimental outcomes and indicated that the field emission enhancement stems from the emitters' geometry as well as the spatial separation. The devised growth protocol is efficient, economic and high-throughput, thus it lays a promising path for exploiting CuO (and possibly other) nanostructures for flexible field emission electronics/displays as well as in vacuum nano-electronic devices.
AIP Conference Proceedings, 2019
Cupric Oxide (CuO), is an inexpensive and non-toxic p-type semiconductor material with a monoclinic crystal structure having indirect band gap (Eg) 1.2 eV-1.9 eV. In this study, co-precipitation method has been employed to synthesize CuO nanoparticles. The samples were calcinated at 200 0 C or 400 0 C for decomposition of hydroxides to oxide. The XRD pattern of the CuO nanoparticles annealed at 400°C exhibited well defined peaks and are consistent with the standard values showing monoclinic structure of CuO with particle size in the range around 10 nm-12 nm and 14 nm-17 nm for slighty different precursor materials both samples annealed at 200°C. The nanoparticles size got aggregated when they are annealed at 400°C. This may be attributed to the agglomeration of the particles at high temperature. Hereby we are emphasizing the fact that the interest on old semiconductor like copper oxide still remains at a time when many new semiconductors such as the perovskites and organic semiconductors are being studied for PV applications is mainly due to sustainability. Both copper and oxygen are abundant elements like silicon and thus there can be no supply concern in the long run.
Field emission properties of CuAlO 2 nanoparticles are reported for the first time, with a low turn-on field of approximately 2 V μm −1 and field enhancement factor around 230. The field emission process follows the standard Fowler-Nordheim tunnelling of cold electron emission. The emission mechanism is found to be a combination of low electron affinity, internal nanostructure and large field enhancement at the low-dimensional emitter tips of the nanoparticles. The field emission properties are comparable to the conventional carbon-based field emitters, and thus can become alternative candidate for field emission devices for low-power panel applications.
Journal of the Chinese …, 2011
Cupric oxide is a p-type semiconductor with a narrow band-gap which is suitable for catalysis, electrochemical cells, field emission devices and gas sensor applications. Despite considerable efforts devoted to the preparation of the nanosized CuO, there is a lack of information about ultrasonic-assisted (US) preparation methods. Nanosized cupric oxide was successfully prepared through different ultrasonic-assisted (US) preparation methods. Furthermore, the influence of preparation method on the structure, morphology and optical properties of nanosized CuO has been reported. XRD patterns were identical to the single-phase pure CuO with a monoclinic structure. The enhancement of the crystallinity and crystallite size was observed for the sample prepared through the US thermal decomposition. The absorption band of CuO nanocrystals prepared through the US liquid hydrolysis shows a clear red shift of about 40 nm compared to those obtained with other preparation methods. Our results indicated that almost spherical CuO nanoparticles with an average size of 65 nm were prepared during the US thermal decomposition, while CuO rod-like nanostructures with an average diameter of about 16 nm were obtained via the US liquid hydrolysis method. The band gap values of nanosized CuO samples were larger than the reported value for the bulk CuO. Synthesized CuO samples by US methods with adjustable and controllable properties make the applicability of cupric oxide even more versatile.
Growth of Flower-like Copper Oxide Nanostructures by Glow Discharge in Water
In this work, synthesis of flower-like copper oxide nanostructures via a plasma-assisted technique based on glow discharge in liquids has been reported for the first time. The preparation process was carried out in a reactor containing a glass discharge chamber with two copper electrodes immersed in distilled water. The effect of distance between electrodes on the rate of nanopowder production and the structural and morphological properties was investigated by XRD and FESEM. From the XRD patterns of as-grown samples, besides the CuO monoclinic structure, reflection peaks corresponding to Cu2O phase were also observed. It was found that Cu2O phase could be easily eliminated by annealing at 400 °C. FESEM images showed that the flower-like copper oxide nanostructures were composed of nanorods in size of a few hundreds of nanometers in length and 50-80 nm in diameter. In addition, the possible formation mechanism of flower-like copper oxide nanostructures was discussed.
Room Temperature Synthesis of Cu2O Nanospheres: Optical Properties and Thermal Behavior
Microscopy and Microanalysis, 2014
The present work reports a simple and easy wet chemistry synthesis of cuprous oxide (Cu2O) nanospheres at room temperature without surfactants and using different precursors. Structural characterization was carried out by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with focused ion beam and energy-dispersive X-ray spectroscopy. The optical band gaps were determined from diffuse reflectance spectroscopy. The photoluminescence behavior of the as-synthesized nanospheres showed significant differences depending on the precursors used. The Cu2O nanospheres were constituted by aggregates of nanocrystals, in which an on/off emission behavior of each individual nanocrystal was identified during transmission electron microscopy observations. The thermal behavior of the Cu2O nanospheres was investigated with in situ X-ray diffraction and differential scanning calorimetry experiments. Remarkable structural differences were observed for the nano...
One Step Synthesis and Optical Evaluation of Copper Oxide (CuO) Nanoparticles
2010
One-dimensional nanostructural materials are currently the focus of considerable interest. Many methods have been used for the preparation of nanoparticles. However, to our knowledge, complex process control, high reaction temperatures or long synthesis time may be required for these approaches. Here we report a novel and simple one-step for synthesis of highly stable and freestanding cupric oxide (CuO) nanoparticles of approximately 10 and 12 nm in size which have been successfully synthesized via electrochemical method. Ultraviolet-visible spectroscopy (UV-VIS), X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) were introduced to characterize the samples. The results indicate that growth conditions are responsible for different sizes.