Swati Das - Academia.edu (original) (raw)

Papers by Swati Das

Journal of Materials Chemistry C, 2014

ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surfa... more ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surface of flexible carbon fabric by a facile chemical route with the assistance of nonionic surfactant PEG-6000. The carbon fabric substrate preserves its high flexibility even after the growth of the entire nanostructure. Moreover, it can be rolled-up and twisted to a large degree without affecting the electrical characteristics. The phase purity and degree of crystallinity of the developed nanostructures were systemically supported by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. A proposed growth mechanism has been offered by thoroughly analyzing the field emission scanning electron microscopic images of the nanostructures grown at different concentrations of PEG. Among the as grown nanostructures, copper oxide nanoknives have exhibited remarkable field emission properties and high stability with a lower turn-on field of 0.9 V μm−1 (10 μA cm−2) at room temperature, which is sufficient for electron emission based devices like field emission displays and vacuum nano-electronic devices.

Journal of Nanoscience and Nanotechnology, Apr 1, 2013

Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template... more Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template free chemical route at different temperatures. Thermal aging followed by higher temperature (350 C, 6 hours) annealing on these architects transformed them into hollow mesospheres consisting of sharp needle like structures with high aspect ratio (∼ 10 3. A detailed analysis of field emission scanning electron microscopy confirmed a uniform registry of the prepared nanostructures. High resolution transmission electron microscopy showed that the as-grown mesospheres have hollow inner cavity with a thin outer shell. X-ray photoelectron spectroscopic analysis showed no obvious changes in the chemical composition of the nanostructures after annealing, confirming that the elements in the final products were in the proper oxidation states. Electron emission under electric field was investigated from these interesting structures. It was found that both of these nanostructures showed electron emission, but emission performance of the hollow mesospheres consisting of nanoneedles exhibited excellent performance with turn-on field as low as 2.8 V/ m and high enhancement factor ∼ 5537.

Journal of Materials Science: Materials in Electronics, 2022

Rare earth-doped phosphor materials have always remained in focus for excellent luminescence prop... more Rare earth-doped phosphor materials have always remained in focus for excellent luminescence properties. Herein we have synthesized Yb3+ and Er3+-doped BaWO4 nanophosphor via facile hydrothermal method with red and green region emissions by 980 nm excitation. Red and green region emissions were observed due to 4F9/2 → 4I15/2 and 2H11/2/4S3/2 → 4I15/2 transitions, respectively, of Er3+, where Yb3+ acts as a sensitizer. The sample characterization was done using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) techniques. The consequences of different concentrations of activator ion (Er3+) in BaWO4: Yb3+, Er3+ were studied from luminescence perspective in detail. The intensity of overall emission varied with altering the power of excitation that influences the photon transfer pathways. It was found that two-photon processes control both red and green emissions in the upconversion process. Decay behavior for both the emission was investigated. Thus, the tunable photoluminescence property suggests its potential in optoelectronic applications.

Carbon, 2018

Amalgamation of excellent properties of semiconductor nanostructure and carbon nanotubes (CNT) cr... more Amalgamation of excellent properties of semiconductor nanostructure and carbon nanotubes (CNT) creates advanced material with superior properties which are otherwise unachievable. Here we report cupric oxide (CuO) nanostructure decorated amorphous carbon nanotubes (aCNT) with improved field emission properties. Sharp wedge shaped CuO nanostructure attached aCNT is prepared by a simple cost effective large scale synthesis procedure. Pristine aCNT and CuO-aCNT hetero structure are characterised by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Field emission properties of CuO-aCNT hybrid structure is compared with bare aCNT sample. The turn-on field of CuO-aCNT in comparison with pristine aCNT is downshifted from 8.07 V/µm to 3.73 V/µm. Density functional theory calculation of aCNT and CuO-aCNT hybrid model has been employed to calculate the work function and hence to estimate the field enhancement factor. This theoretical study has supported our experimental result. Furthermore, the origin of local field enhancement of the hybrid nanostructure is examined by finite element modelling method.

2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), 2016

Well-dispersed exfoliated white graphene (h-BN) nanosheet in transformer oil was prepared at vari... more Well-dispersed exfoliated white graphene (h-BN) nanosheet in transformer oil was prepared at various weight percentages. The nanofluid transformer oil showed excellent stability over long time duration and significant improvement of thermal conductivity (>45% for 0.05 wt.%)due to large surface area and high thermal conductivity of h-BN nanosheets.

New Journal of Chemistry, 2015

We have demonstrated a simplified reduction technique of Eu3+ to Eu2+ in complexation with an azo... more We have demonstrated a simplified reduction technique of Eu3+ to Eu2+ in complexation with an azo-pyridine graphene oxide composite and its effect on photoluminescence.

Journal of Materials Chemistry C, 2014

ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surfa... more ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surface of flexible carbon fabric by a facile chemical route with the assistance of nonionic surfactant PEG-6000. The carbon fabric substrate preserves its high flexibility even after the growth of the entire nanostructure. Moreover, it can be rolled-up and twisted to a large degree without affecting the electrical characteristics. The phase purity and degree of crystallinity of the developed nanostructures were systemically supported by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. A proposed growth mechanism has been offered by thoroughly analyzing the field emission scanning electron microscopic images of the nanostructures grown at different concentrations of PEG. Among the as grown nanostructures, copper oxide nanoknives have exhibited remarkable field emission properties and high stability with a lower turn-on field of 0.9 V μm−1 (10 μA cm−2) at room temperature, which is sufficient for electron emission based devices like field emission displays and vacuum nano-electronic devices.

Journal of Applied Polymer Science, 2013

Conducting polymer polypyrrole is reported to have a poor adhesion to substrate which limits its ... more Conducting polymer polypyrrole is reported to have a poor adhesion to substrate which limits its applicability as thin films. In this article, we report synthesis of well-formed and continuous film of polypyrrole through treatment of hydrophobic substrates. However, in place of the widely used organosilanes, the substrates were simply treated with surfactant cetyl trimethylammonium bromide (CTAB) prior to vapor phase polymerization under controlled environment. Polypyrrole films formed on CTAB pretreated substrates were found to have improved adhesion and continuity compared to the films formed on untreated substrates. The improved adhesion results in better electronic properties as seen during Electron field emission studies. Based on contact angle analysis, we propose that CTAB molecules act as anchoring agents for the oxidant layer on the substrate and hence assist in the deposition of a more continuous polypyrrole film.

Applied Physics A, 2008

Effects of temperature and the aspect ratio on the electron field emission properties of vertical... more Effects of temperature and the aspect ratio on the electron field emission properties of vertically aligned carbon nanofibers in thin-film form were studied in detail. Vertically aligned carbon nanofibers have been synthesized on silicon substrates via a direct current plasma enhanced chemical vapor deposition technique. Surface morphologies of the films were studied by an atomic force microscope. It was found that the length of the nanofibers increased and the diameter decreased as the thickness of the Ni catalyst film decreased. The threshold field for the electron field emission was found to be in the range from 4.3 to 5.4 V/µm for carbon nanofibers having different aspect ratios. The threshold field for carbon nanofibers having diameter ∼ 200 nm and aspect ratio ∼ 7.5 was found to decrease from 4.8 to 2.1 V/µm when the temperature was raised from 27 to 350 • C. This dependence was due to the change in work function of the nanofibers with temperature. The field enhancement factor, the current density and the effective work function were calculated and used to explain the emission mechanism.

Journal of Electronic Materials

ACS Omega, 2017

Developing portable, lightweight, and flexible energy storage systems has become a necessity with... more Developing portable, lightweight, and flexible energy storage systems has become a necessity with the advent of wearable electronic devices in our modern society. This work focuses on the fabrication of Co 3 O 4 nanowires on a flexible carbon fabric (CoNW/CF) substrate by a simple cost-effective hydrothermal route. The merits of the high surface area of the prepared Co 3 O 4 nanostructures result in an exceptionally high specific capacitance of 3290 F/g at a scan rate of 5 mV/s, which is close to their theoretical specific capacitance. Furthermore, a solid-state symmetric supercapacitor (SSC) based on CoNW/CF (CoNW/CF//CoNW/CF) was fabricated successfully. The device attains high energy and power densities of 6.7 Wh/kg and 5000 W/kg. It also demonstrates excellent rate capability and retains 95.3% of its initial capacitance after 5000 cycles. Further, the SSC holds its excellent performance at severe bending conditions. When a series assembly of four such devices is charged, it can store sufficient energy to power a series combination of five light-emitting diodes. Thus, this SSC device based on a threedimensional coaxial architecture opens up new strategies for the design of next-generation flexible supercapacitors.

ACS Applied Materials & Interfaces, 2016

The Journal of Physical Chemistry C, 2015

ABSTRACT

J. Mater. Chem. C, 2015

Ultra-high red luminescence is demonstrated from rare-earth free as well as nontoxic cuprous iodi... more Ultra-high red luminescence is demonstrated from rare-earth free as well as nontoxic cuprous iodide nanophosphors through controlled defect level engineering.

Physica B: Condensed Matter, 2005

P-type transparent-conducting CuAlO 2+x thin films were deposited on silicon and glass substrates... more P-type transparent-conducting CuAlO 2+x thin films were deposited on silicon and glass substrates by reactive direct current sputtering of a prefabricated metal powder target having 1:1 atomic ratio of Cu and Al in oxygen-diluted argon atmosphere. XRD spectrum confirmed the proper phase formation of the material. UV-Vis-NIR spectrophotometric measurements showed high transparency of the films in the visible region with direct and indirect band gap values around 3.90 and 1.89 eV, respectively. The room temperature conductivity of the film was of the order of 0.22 S cm À1 and the activation energy was 0.25eV.Seebeckcoefficientatroomtemperatureshowedavalueof+115mV/Kconfirmingthep−typenatureofthefilm.RoomtemperatureHalleffectmeasurementalsoindicatedpositivevalueofHallcoefficientwithacarrierconcentration0.25 eV. Seebeck coefficient at room temperature showed a value of +115 mV/K confirming the p-type nature of the film. Room temperature Hall effect measurement also indicated positive value of Hall coefficient with a carrier concentration 0.25eV.Seebeckcoefficientatroomtemperatureshowedavalueof+115mV/Kconfirmingthep−typenatureofthefilm.RoomtemperatureHalleffectmeasurementalsoindicatedpositivevalueofHallcoefficientwithacarrierconcentration4.4 Â 10 17 cm À3. We have also observed the low macroscopic field emission, from the wide band gap p-CuAlO 2+x thin film deposited on glass substrate. The emission properties have been studied for different anode-sample spacing. The threshold field was found to be as low as around 0.5-1.1 V/mm. This low threshold is attributed primarily to the internal nanostructure of the thin film, which causes considerable geometrical field enhancement inside the film as well as at the film/vacuum interface.

Journal of Nanoscience and Nanotechnology, 2013

Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template... more Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template free chemical route at different temperatures. Thermal aging followed by higher temperature (350 C, 6 hours) annealing on these architects transformed them into hollow mesospheres consisting of sharp needle like structures with high aspect ratio (∼ 10 3. A detailed analysis of field emission scanning electron microscopy confirmed a uniform registry of the prepared nanostructures. High resolution transmission electron microscopy showed that the as-grown mesospheres have hollow inner cavity with a thin outer shell. X-ray photoelectron spectroscopic analysis showed no obvious changes in the chemical composition of the nanostructures after annealing, confirming that the elements in the final products were in the proper oxidation states. Electron emission under electric field was investigated from these interesting structures. It was found that both of these nanostructures showed electron emission, but emission performance of the hollow mesospheres consisting of nanoneedles exhibited excellent performance with turn-on field as low as 2.8 V/ m and high enhancement factor ∼ 5537.

Dalton Transactions, 2014

Experimentally observed excellent cold cathode emission characteristics of chemically synthesized... more Experimentally observed excellent cold cathode emission characteristics of chemically synthesized CuPc nanotubes and theoretical justifications via finite element method simulation.

Journal of Materials Chemistry C, 2014

ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surfa... more ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surface of flexible carbon fabric by a facile chemical route with the assistance of nonionic surfactant PEG-6000. The carbon fabric substrate preserves its high flexibility even after the growth of the entire nanostructure. Moreover, it can be rolled-up and twisted to a large degree without affecting the electrical characteristics. The phase purity and degree of crystallinity of the developed nanostructures were systemically supported by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. A proposed growth mechanism has been offered by thoroughly analyzing the field emission scanning electron microscopic images of the nanostructures grown at different concentrations of PEG. Among the as grown nanostructures, copper oxide nanoknives have exhibited remarkable field emission properties and high stability with a lower turn-on field of 0.9 V μm−1 (10 μA cm−2) at room temperature, which is sufficient for electron emission based devices like field emission displays and vacuum nano-electronic devices.

Journal of Nanoscience and Nanotechnology, Apr 1, 2013

Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template... more Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template free chemical route at different temperatures. Thermal aging followed by higher temperature (350 C, 6 hours) annealing on these architects transformed them into hollow mesospheres consisting of sharp needle like structures with high aspect ratio (∼ 10 3. A detailed analysis of field emission scanning electron microscopy confirmed a uniform registry of the prepared nanostructures. High resolution transmission electron microscopy showed that the as-grown mesospheres have hollow inner cavity with a thin outer shell. X-ray photoelectron spectroscopic analysis showed no obvious changes in the chemical composition of the nanostructures after annealing, confirming that the elements in the final products were in the proper oxidation states. Electron emission under electric field was investigated from these interesting structures. It was found that both of these nanostructures showed electron emission, but emission performance of the hollow mesospheres consisting of nanoneedles exhibited excellent performance with turn-on field as low as 2.8 V/ m and high enhancement factor ∼ 5537.

Journal of Materials Science: Materials in Electronics, 2022

Rare earth-doped phosphor materials have always remained in focus for excellent luminescence prop... more Rare earth-doped phosphor materials have always remained in focus for excellent luminescence properties. Herein we have synthesized Yb3+ and Er3+-doped BaWO4 nanophosphor via facile hydrothermal method with red and green region emissions by 980 nm excitation. Red and green region emissions were observed due to 4F9/2 → 4I15/2 and 2H11/2/4S3/2 → 4I15/2 transitions, respectively, of Er3+, where Yb3+ acts as a sensitizer. The sample characterization was done using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) techniques. The consequences of different concentrations of activator ion (Er3+) in BaWO4: Yb3+, Er3+ were studied from luminescence perspective in detail. The intensity of overall emission varied with altering the power of excitation that influences the photon transfer pathways. It was found that two-photon processes control both red and green emissions in the upconversion process. Decay behavior for both the emission was investigated. Thus, the tunable photoluminescence property suggests its potential in optoelectronic applications.

Carbon, 2018

Amalgamation of excellent properties of semiconductor nanostructure and carbon nanotubes (CNT) cr... more Amalgamation of excellent properties of semiconductor nanostructure and carbon nanotubes (CNT) creates advanced material with superior properties which are otherwise unachievable. Here we report cupric oxide (CuO) nanostructure decorated amorphous carbon nanotubes (aCNT) with improved field emission properties. Sharp wedge shaped CuO nanostructure attached aCNT is prepared by a simple cost effective large scale synthesis procedure. Pristine aCNT and CuO-aCNT hetero structure are characterised by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Field emission properties of CuO-aCNT hybrid structure is compared with bare aCNT sample. The turn-on field of CuO-aCNT in comparison with pristine aCNT is downshifted from 8.07 V/µm to 3.73 V/µm. Density functional theory calculation of aCNT and CuO-aCNT hybrid model has been employed to calculate the work function and hence to estimate the field enhancement factor. This theoretical study has supported our experimental result. Furthermore, the origin of local field enhancement of the hybrid nanostructure is examined by finite element modelling method.

2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), 2016

Well-dispersed exfoliated white graphene (h-BN) nanosheet in transformer oil was prepared at vari... more Well-dispersed exfoliated white graphene (h-BN) nanosheet in transformer oil was prepared at various weight percentages. The nanofluid transformer oil showed excellent stability over long time duration and significant improvement of thermal conductivity (>45% for 0.05 wt.%)due to large surface area and high thermal conductivity of h-BN nanosheets.

New Journal of Chemistry, 2015

We have demonstrated a simplified reduction technique of Eu3+ to Eu2+ in complexation with an azo... more We have demonstrated a simplified reduction technique of Eu3+ to Eu2+ in complexation with an azo-pyridine graphene oxide composite and its effect on photoluminescence.

Journal of Materials Chemistry C, 2014

ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surfa... more ABSTRACT Sharp knife edged copper oxide (CuO) nano architectures were directly grown on the surface of flexible carbon fabric by a facile chemical route with the assistance of nonionic surfactant PEG-6000. The carbon fabric substrate preserves its high flexibility even after the growth of the entire nanostructure. Moreover, it can be rolled-up and twisted to a large degree without affecting the electrical characteristics. The phase purity and degree of crystallinity of the developed nanostructures were systemically supported by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. A proposed growth mechanism has been offered by thoroughly analyzing the field emission scanning electron microscopic images of the nanostructures grown at different concentrations of PEG. Among the as grown nanostructures, copper oxide nanoknives have exhibited remarkable field emission properties and high stability with a lower turn-on field of 0.9 V μm−1 (10 μA cm−2) at room temperature, which is sufficient for electron emission based devices like field emission displays and vacuum nano-electronic devices.

Journal of Applied Polymer Science, 2013

Conducting polymer polypyrrole is reported to have a poor adhesion to substrate which limits its ... more Conducting polymer polypyrrole is reported to have a poor adhesion to substrate which limits its applicability as thin films. In this article, we report synthesis of well-formed and continuous film of polypyrrole through treatment of hydrophobic substrates. However, in place of the widely used organosilanes, the substrates were simply treated with surfactant cetyl trimethylammonium bromide (CTAB) prior to vapor phase polymerization under controlled environment. Polypyrrole films formed on CTAB pretreated substrates were found to have improved adhesion and continuity compared to the films formed on untreated substrates. The improved adhesion results in better electronic properties as seen during Electron field emission studies. Based on contact angle analysis, we propose that CTAB molecules act as anchoring agents for the oxidant layer on the substrate and hence assist in the deposition of a more continuous polypyrrole film.

Applied Physics A, 2008

Effects of temperature and the aspect ratio on the electron field emission properties of vertical... more Effects of temperature and the aspect ratio on the electron field emission properties of vertically aligned carbon nanofibers in thin-film form were studied in detail. Vertically aligned carbon nanofibers have been synthesized on silicon substrates via a direct current plasma enhanced chemical vapor deposition technique. Surface morphologies of the films were studied by an atomic force microscope. It was found that the length of the nanofibers increased and the diameter decreased as the thickness of the Ni catalyst film decreased. The threshold field for the electron field emission was found to be in the range from 4.3 to 5.4 V/µm for carbon nanofibers having different aspect ratios. The threshold field for carbon nanofibers having diameter ∼ 200 nm and aspect ratio ∼ 7.5 was found to decrease from 4.8 to 2.1 V/µm when the temperature was raised from 27 to 350 • C. This dependence was due to the change in work function of the nanofibers with temperature. The field enhancement factor, the current density and the effective work function were calculated and used to explain the emission mechanism.

Journal of Electronic Materials

ACS Omega, 2017

Developing portable, lightweight, and flexible energy storage systems has become a necessity with... more Developing portable, lightweight, and flexible energy storage systems has become a necessity with the advent of wearable electronic devices in our modern society. This work focuses on the fabrication of Co 3 O 4 nanowires on a flexible carbon fabric (CoNW/CF) substrate by a simple cost-effective hydrothermal route. The merits of the high surface area of the prepared Co 3 O 4 nanostructures result in an exceptionally high specific capacitance of 3290 F/g at a scan rate of 5 mV/s, which is close to their theoretical specific capacitance. Furthermore, a solid-state symmetric supercapacitor (SSC) based on CoNW/CF (CoNW/CF//CoNW/CF) was fabricated successfully. The device attains high energy and power densities of 6.7 Wh/kg and 5000 W/kg. It also demonstrates excellent rate capability and retains 95.3% of its initial capacitance after 5000 cycles. Further, the SSC holds its excellent performance at severe bending conditions. When a series assembly of four such devices is charged, it can store sufficient energy to power a series combination of five light-emitting diodes. Thus, this SSC device based on a threedimensional coaxial architecture opens up new strategies for the design of next-generation flexible supercapacitors.

ACS Applied Materials & Interfaces, 2016

The Journal of Physical Chemistry C, 2015

ABSTRACT

J. Mater. Chem. C, 2015

Ultra-high red luminescence is demonstrated from rare-earth free as well as nontoxic cuprous iodi... more Ultra-high red luminescence is demonstrated from rare-earth free as well as nontoxic cuprous iodide nanophosphors through controlled defect level engineering.

Physica B: Condensed Matter, 2005

P-type transparent-conducting CuAlO 2+x thin films were deposited on silicon and glass substrates... more P-type transparent-conducting CuAlO 2+x thin films were deposited on silicon and glass substrates by reactive direct current sputtering of a prefabricated metal powder target having 1:1 atomic ratio of Cu and Al in oxygen-diluted argon atmosphere. XRD spectrum confirmed the proper phase formation of the material. UV-Vis-NIR spectrophotometric measurements showed high transparency of the films in the visible region with direct and indirect band gap values around 3.90 and 1.89 eV, respectively. The room temperature conductivity of the film was of the order of 0.22 S cm À1 and the activation energy was 0.25eV.Seebeckcoefficientatroomtemperatureshowedavalueof+115mV/Kconfirmingthep−typenatureofthefilm.RoomtemperatureHalleffectmeasurementalsoindicatedpositivevalueofHallcoefficientwithacarrierconcentration0.25 eV. Seebeck coefficient at room temperature showed a value of +115 mV/K confirming the p-type nature of the film. Room temperature Hall effect measurement also indicated positive value of Hall coefficient with a carrier concentration 0.25eV.Seebeckcoefficientatroomtemperatureshowedavalueof+115mV/Kconfirmingthep−typenatureofthefilm.RoomtemperatureHalleffectmeasurementalsoindicatedpositivevalueofHallcoefficientwithacarrierconcentration4.4 Â 10 17 cm À3. We have also observed the low macroscopic field emission, from the wide band gap p-CuAlO 2+x thin film deposited on glass substrate. The emission properties have been studied for different anode-sample spacing. The threshold field was found to be as low as around 0.5-1.1 V/mm. This low threshold is attributed primarily to the internal nanostructure of the thin film, which causes considerable geometrical field enhancement inside the film as well as at the film/vacuum interface.

Journal of Nanoscience and Nanotechnology, 2013

Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template... more Cupric oxide mesospheres composed of its nanoparticles have been synthesized by a simple template free chemical route at different temperatures. Thermal aging followed by higher temperature (350 C, 6 hours) annealing on these architects transformed them into hollow mesospheres consisting of sharp needle like structures with high aspect ratio (∼ 10 3. A detailed analysis of field emission scanning electron microscopy confirmed a uniform registry of the prepared nanostructures. High resolution transmission electron microscopy showed that the as-grown mesospheres have hollow inner cavity with a thin outer shell. X-ray photoelectron spectroscopic analysis showed no obvious changes in the chemical composition of the nanostructures after annealing, confirming that the elements in the final products were in the proper oxidation states. Electron emission under electric field was investigated from these interesting structures. It was found that both of these nanostructures showed electron emission, but emission performance of the hollow mesospheres consisting of nanoneedles exhibited excellent performance with turn-on field as low as 2.8 V/ m and high enhancement factor ∼ 5537.

Dalton Transactions, 2014

Experimentally observed excellent cold cathode emission characteristics of chemically synthesized... more Experimentally observed excellent cold cathode emission characteristics of chemically synthesized CuPc nanotubes and theoretical justifications via finite element method simulation.