producing less oxidized graphene electrochemical flakes...
TRANSCRIPT
-
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 [email protected]@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