Producing less oxidized graphene Electrochemical flakes...

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  • Production of High-Quality Exfoliated graphene using Two step electrochemical approach

    Ashutosh K. Singha, Maria Page-Perezb, Nael Yasria, Stuart Holmesb and Edward PL Robertsa

    aDepartment of Chemical and Petroleum Engineering | Schul ich School of Engineering bSchool of Chemical Engineering and Analyt ical Science | University of Manchester | UK

    ashutosh.s ingh@ucalgary.caedward.roberts@ucalgary.ca

    ReferencesJ. Am. Chem. Soc. 2017, 139, 48, 17446-17456

    Singh et. al. (coming soon)

    Chemical vs Electrochemical Approach

    Material Characterization

    Electrochemical Preparation Process details

    Power

    supply

    Graphite (Anode)Stainless steel

    (Cathode)

    High Cell voltage ~ 10 V

    Longer duration ( 5 – 6 days)

    Toxic and corrosive chemicals

    Major Pains

    Environmentally friendly chemicals

    Shorter duration (< 1 day)

    Solution

    0 2000 4000 6000 8000 100001.25

    1.50

    1.75

    2.00

    2.25

    2.50

    2.75

    3.00

    Cell

    Po

    tential (V

    )

    Time (s)

    5 mA cm-2

    10 mA cm-2

    15 mA cm-2

    25 mA cm-2

    30 mA cm-2

    0.00 0.01 0.02 0.03 0.040.0

    0.1

    0.2

    0.3

    0.4

    0.5

    0.6

    Absorbance

    Linear Fitting

    Absorb

    ance (

    a.u

    .)

    Concentration (mg ml-1)

    Slope = 1329 mL mg-1 m

    -1

    R2 = 0.99

    Graphene

    materials

    Characteristic

    absorbance

    peak

    Graphene Oxide 230 nm

    EEG (our

    method)

    267 nm

    Graphene

    materials

    Slope factor

    (mL mg-1 m-1)

    Graphene Oxide

    (Hummer’s

    Method)

    49*

    EEG (This

    method)

    1329

    Elements detected(XPS)

    Atomic Conc. (%)

    Carbon 93.19

    Nitrogen 0.53

    Oxygen 6.28

    C/O (EEG Our method) 14.8 (~15)

    C/O (Graphene Oxide) 2 – 4*

    C/O (reduced Graphene Oxide)

    ~ 30 *

    396 398 400 402 404

    Pyridinic

    N oxides

    Quaternary N

    Inte

    nsity (

    a.u

    .)

    Binding Energy (eV)

    Pyridinic N

    164 166 168 170 172

    Inte

    nsity (

    a.u

    .)

    Binding Energy (eV)

    C-SOx-C

    x = 2,3,4

    10 μm

    0-110

    1-210

    1.1 nm

    1 2 3 4 5 6 7 8 90

    10

    20

    30

    40

    50

    Pe

    rce

    nta

    ge

    Fla

    ke

    s (

    %)

    Number of Layers

    AFM analysis

    Chemical

    Electrochemical

    ElectrochemicalIntercalation

    Exfoliation

    Exfoliated Graphene Flakes

    GIC studies

    OH− ion

    Objective:

    • Producing less oxidized graphene flakes

    • Potentially replace reduction process

    • Scalable process

    • How about Alkaline medium ?

    Other Benefits:

    • Tunable Graphene properties

    Conclusion

    • More reduced graphene produced

    • N and S doping

    • Less disrupted π structure

    • 92% flakes – less than 4 layers

    0

    1x104

    2x104

    3x104

    4x104

    5x104

    HIThis Method

    EEG

    Hydrazine

    Ele

    ctr

    ical C

    onductivity (

    S m

    -1)

    Reduction method

    Thermal

    Ascorbic

    Acid

    https://pubs.acs.org/action/showCitFormats?doi=10.1021%2Fjacs.7b08515https://pubs.acs.org/action/showCitFormats?doi=10.1021%2Fjacs.7b08515