Nitrogen Enriched Carbon Coated Chemically Modified Graphene Scaffold

For Capacitive Energy Storage    

By: Abubakar Sadique Sunil Kanamarlapudi Pooja Sahare Soundarya K.

OUTLINEGrapheneSuper CapacitorGraphene OxideObjectivesExperimental ProcedureCharacterization and ResultsConclusions

GrapheneGraphene is a single tightly packed layer of

carbon atoms that are bonded together in a hexagonal honeycomb lattice.

Layers of Graphene stacked on top of each other form graphite , with an inter planar spacing of 0.335 nano metres.

The lightest material known (with 1 square meter coming in at around 0.77 milligrams),

The strongest compound discovered (between 100-300 times stronger than steel)

The best conductor of electricity known

Properties of GraphenePROPERTY RANGE

Theoretical specific surface area 2630 m2 g-1

Young’s modulus 1 T pa

Fracture strength 120 M pa

Carrier mobility at room temperature

10,000 cm2 V-1 S-1

Optical transmittance 97.7%

Electrical conductivity 5000 W m-1 K-1

Specific capacity 80 mF cm-2

Specific capacitance 550 F g-1

Charge Storage

Graphene as Super capacitorGraphene has substantially more

relative surface area.Thus, as a super capacitor material

it will be better at storing electrostatic charge.

Material made up of one single atomic layer, it is lighter.

Ecologically friendly, unlike most other forms of energy storage.

Graphene Oxide (GO):Structurally, GO can be visualized as a graphene sheet with its

basal plane decorated by oxygen-containing groups. Due to high affinity to water molecules by these groups, GO is

hydrophilic and can be dissolved in water. The solubility in water makes the deposition of the thin films

of the GO straightforward. GO is a poor conductor but its chemical treatment by light,

heat, or chemical reduction can restore most properties of the famed pristine graphene.

OBJECTIVES: The modified Hummer’s hydrothermal method was

employed to prepare reduced Graphene oxide using the exfoliated graphite.

Chemically modify reduced Graphene oxide by enriching with nitrogen and coating with carbon sources.

Characterize the different types of samples for different properties such as morphology, conductance, electrochemical properties, absorbance, and zeta potential.

EXPERIMENTAL PROCEDURE

Exfoliated Graphite(EG): Carbon content=99%,

Apparent Density=0.0025g/cc Graphite Nano Pellets(GNP): Carbon content=99%,

Apparent Density=0.06g/cc H2SO4: As a medium for oxidizer

KMnO4: As an oxidizer

H2O2: To remove excess KMnO4

HCl: To remove the manganese salts DI water: For dilution and neutralizing

MATERIALS AND THEIR PROPERTIES:

PREPARATION OF GRAPHITE NANO PLATELETS (GNPs):

Exfoliated Graphite + Acetone•Mechanical Stirring

Resulting Solution•Dried

Dried Solid Weighed•GNP’s Formed

SYNTHESIS OF GRAPHENE OXIDE:

KMnO4+ 3H2SO4K+ +MnO3

+ + H3O+ + 3HSO4

-

MnO3+ + MnO4

- Mn2O7

SYNTHESIS OF GRAPHENE OXIDE:

SYNTHESIS OF RGOD-Reduced Graphene oxide C coated with D-Glucose:

SYNTHESIS OF RGODE-Reduced Graphene oxide ‘N’ enriched with (EDA) and ‘C’ coated with D-Glucose

FESEMFE-SEM images of (a) GO (b) RGOD8(c) RGODE8 (d) RGOD20 (e) RGODE20

CHARACTERIZATION

Results of FESEM1) GO Sample was gold sputtered as it was least conductive,

and overall image showed that it has a layered structure.

2) RGOD sample had carbon spheres due to D-glucose which

was used as carbon source for coating.

3) RGODE samples had less carbon spheres and more porous

structure due to addition of nitrogen source EDA.

4) Time of reduction of GO is directly proportional to porous

morphology and inversely proportional to the amount of

carbon spheres.

SEM ELEMENTAL MAPPINGElemental SEM Mapping was done for primary elemental analysis and data

obtained is not accurate for Nitrogen content in the samples.

•GO:

•RGOD8:

•RGODE8:

•RGOD20:

•RGODE20:

Results of SEMGO mapping showed less carbon content due to

impurities during synthesis.

Mapping confirmed that RGODE had less oxygen

content as compared to RGOD and more carbon

content.

With increase in time of reduction, the carbon

content increases in case of RGODE whereas in

RGOD oxygen content was more.

UV SPECTROSCOPY All the UV-Vis absorption spectra were conducted on a

Perkin-Elmer Lambda 950 UV-Vis-NIR spectrophotometer.

200 400 600 800 1000

0.050.100.150.200.250.300.350.400.450.500.550.600.650.700.750.800.850.900.951.00

Ab

sorb

an

ce(A

)

Wavelength(nm)

RGODE20 RGOD20 RGODE8 RGOD8 GO

RESULTS of UV:

1. The quality of results depends on the dispersion of particles and

viscous nature of the solution.

2. The noise in the graph is directly proportional to the

concentration of the solute in the solution.

3. The peak of RGO shifted to higher values with increase in time

of reduction.

4. The absorbance of RGO was increased with respect to base

material on addition of ‘C’ and ‘N’.

CYCLIC VOLTAMETRY:

Cyclic Voltammetry is used to determine the electrochemical properties of electrodes using three electrode system.RGO is used as working electrode, Pt is used as the counter electrode and Ag/AgCl is the reference electrode.1M of H2SO4 is used as the electrolyte in aqueous system.

-1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

Cu

rre

nt (

A)

Potential (V)

0.01 0.1 0.05

Scan Rate(V/s)

CYCLIC VOLTAMETRY:

RESULTS OF CV

1) Current variation was studied at different scan rates, from

which capacitance and specific capacitance was calculated.

2) As scan rate increases the specific capacitance was found to

decrease because the ion migration from the electrode

reduces.

3) The RGOED20 sample was observed to have higher value of

specific capacitance than other conventional electrodes.

• Modified hummer’s method was employed to generate highly oxidized Graphene

oxide. Reduced Graphene oxide (RGO) was prepared by hydrothermal method .GO is

enriched with nitrogen which is found to improve the capacitive property.

• The content of oxygen was significantly reduced as the reduction duration was

increased. The comparison was done with two samples having reduction time 8 Hrs.

and 20 Hrs. respectively. It was found that the oxygen content for the latter was 50%

lesser than the former.

CONCLUSIONS:

• The SEM mapping results showed the distribution of elements mainly carbon, oxygen and

nitrogen in the respective samples. The concentration of oxygen was less in the samples

containing Nitrogen.

• Characterization techniques showed that nitrogen enriched carbon coated RGO had higher

porosity and lower density which is a prerequisite for electrode material.

• Quality of RGO improves and Nitrogen enrichment decreases with increase in time of reduction.

• N’ enriched RGO was found to have higher value of specific

capacitance

CONCLUSIONS:

The Carbon Spheres observed in the FESEM Analysis showed that this

technique of Carbon coating with D-Glucose can result in formation of such

compounds.

The RGO with ‘N’ and ‘C’ content can be effectively used as electrode

material for capacitive energy storage.

The Automobile and Telecom industry needs a new source for battery, i.e.

the Super capacitors which can be interpreted from this type of materials to

give high efficiency and longer life as compared to conventional materials.

FUTURE WORKS

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