The electron field emission from metal nanoparticle decorated hydrogen exfoliated graphene (metal/HEG) occurs at low turn on and threshold fields due to its low work function and high field enhancement factor. © 2011 The Royal Society of Chemistry.

Sundara Ramaprabhu

Department Of Physics

Electron field emission

ELECTRON FIELD EMISSION PROPERTIES

Graphene sheets

High field

Low work function

Metal nanoparticles

THRESHOLD FIELDS

field emission

Graphene

Hydrogen

Nanoparticles

Electron emission

Graphite

Lead

metal nanoparticle

Platinum

Silver

article

chemistry

electrode

electron

ultrastructure

Electrodes

Electrons

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Nanoscale

We report a large scale root to assemble hierarchical copper-based nanostructures on nitrogen-doped graphene sheets by a pH followed by a temperature-directed self-assembly process and their electron field emission studies. Starting with a controlled pH directed self-assembly root, we assembled Cu(OH)2 NRs on NGS and further reassembled it to 1D Cu NPAs and CuO NRs by thermal annealing in H2 and Ar atmosphere, respectively. The field emission characteristics are precisely studied, which depicts a significantly lower threshold and turn-on field for 1D Cu NPAs-NGS-based emitter compared to CuO NRs-NGS and Cu(OH)2 NRs-NGS. Also it exhibited about 3 and 27 times higher emission current density than its oxide and hydroxide counterpart under a moderate field of 1 V/μm. The enhanced field emission behavior of 1D Cu NPAs-NGS is attributed to the low work function, the easy electron tunneling from the one-dimensional arrangement of Cu NPs, which increases the emission sites and hence the FE current density. On the basis of easy large-scale synthesis techniques and better FE performances, these hierarchical nanostructures offer prospects for understanding the effect of linear arrangement of nanoparticles on FE, which can be envisioned for design, fabrication, and optimization of cold cathode devices. © 2015 American Chemical Society.

Journal of Physical Chemistry C

Directed self assembly of copper-based hierarchical nanostructures on nitrogen-doped graphene and their field emission studies

In the present letter, field emission property of highly wrinkled hydrogen exfoliated graphene (HEG) was studied using an indigenously fabricated setup under ∼ 10-6 mbar pressure. Graphene was coated on a flexible carbon cloth by spin coating for the field emission study. The turn on voltage obtained for a HEG field emitter is around 1.18 V/μm. Further, the field emission property of HEG was improved by decorating metal oxide over HEG. The stability of the field emitter was tested and field enhancement factor was calculated using Fowler-Nordheim plot. © 2011 American Institute of Physics.

Fulltext

Applied Physics Letters

Cold field emission from hydrogen exfoliated graphene composites

A hybrid nanostructure consisting of 1D carbon nanotubes and 2D graphene was successfully synthesized. Nanofluids were made by dispersing the hybrid nanostructure in deionized (DI) water and ethylene glycol (EG) separately, without any surfactant. Later the thermal conductivity and heat transfer coefficient of the nanofluids were experimentally measured. Meanwhile, multiwalled carbon nanotubes (MWNT) were prepared by catalytic chemical vapor deposition (CCVD), and hydrogen exfoliated graphene (HEG) was synthesized by exfoliating graphite oxide in a hydrogen atmosphere. The hybrid nanostructure (f-MWNT+f-HEG) of functionalized MWNT (f-MWNT) and functionalized HEG (f-HEG) was prepared by a post mixing technique, and the sample was characterized by powder X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. Thermal conductivity of the nanofluids was measured for different volume fractions of f-MWNT+f-HEG at different temperatures. The hybrid nanostructure dispersed in the DI water based nanofluid shows a thermal conductivity enhancement of 20% for a volume fraction of 0.05%. Similarly, for a Reynolds number of 15500, the enhancement of the heat transfer coefficient is about 289% for a 0.01% volume fraction of f-MWNT+f-HEG. © 2011 The Royal Society of Chemistry.

Experimental investigation of the thermal transport properties of a carbon nanohybrid dispersed nanofluid

The present work describes the field emission characteristics of nanocrystalline metal clusters decorated multi walled carbon nanotubes (MWNT) field emitters fabricated over flexible graphitized carbon cloth. MWNT have been synthesized by catalytic chemical vapour decomposition (CCVD) of acetylene over Rare Earth (RE) based AB2 (DyNi2) alloy hydride catalyst. Fine powders of RE based AB2 alloy hydride catalysts have been prepared by hydrogen decrepitation technique. The as-grown carbon nanotubes (CNTs) are purified by acid and heat treatments and characterized using XRD, SEM and TEM. Purified MWNT have been decorated with nanocrystalline Pd, Pt and Pt-Ru metal clusters using a simple chemical reduction method. The characterization of metal decorated CNTs were done by using XRD, SEM, TEM, HRTEM and EDX. Nanocrystalline Pd, Pt and Pt-Ru metal clusters decorated MWNT field emitters have been fabricated over graphitized carbon fabric using spin coating method. The field emission characteristics have been studied using an indigenously fabricated set up and the results are discussed. The samples show excellent emission properties with a fairly stable emission current over a period of 4 h. As the presence of the graphitic layer provides strong adhesion between the nanotubes and carbon cloth, the use of graphitized carbon cloth as substrate opens new possibilities for CNT field emitters. © 2007 Springer Science+Business Media B.V.

Journal of Nanoparticle Research

Electron field emitters based on multiwalled carbon nanotubes decorated with nanoscale metal clusters

Multi-walled carbon nanotubes (MWCNTs) have been directly grown over a flexible graphitized carbon fabric by water assisted chemical vapor deposition. Field emission properties are compared with randomly oriented multi-walled and single walled carbon nanotube field emitters obtained by spin coating on to carbon fabric. The MWCNTs and single walled carbon nanotubes (SWCNTs) used in spin coating were characterized by X-ray diffraction (XRD) and Raman spectroscopy. High resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) were used to characterize the field emitters. The use of graphitized carbon fabric as substrate has brought in flexibility in the fabrication of carbon nanotube field emitters. The samples show good field emission properties with a fairly stable emission current. Analysis of field emission based on the Fowler-Nordheim theory reveals current saturation effects at high applied fields for all the samples. © 2008 Elsevier Ltd. All rights reserved.

Carbon

Field emission from carbon nanotubes on a graphitized carbon fabric

Applied Surface Science

Field emission arrays fabricated utilizing conjugated ZnO quantum dot/carbon nanotube hybrid nanocomposite

Effect of metal nanoparticles decoration on electron field emission property of graphene sheets

Journal	Nanoscale
ISSN	20403364
Open Access	No