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Production of High-Quality Exfoliated graphene using Two step electrochemical approach Ashutosh K. Singh a , Maria Page-Perez b , Nael Yasri a , Stuart Holmes b and Edward PL Roberts a a Department of Chemical and Petroleum Engineering | Schulich School of Engineering b School of Chemical Engineering and Analytical Science | University of Manchester | UK [email protected] [email protected] References J. 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 10000 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 Cell Potential (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 0.04 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Absorbance Linear Fitting Absorbance (a.u.) Concentration (mg ml -1 ) Slope = 1329 mL mg -1 m -1 R 2 = 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 Intensity (a.u.) Binding Energy (eV) Pyridinic N 164 166 168 170 172 Intensity (a.u.) Binding Energy (eV) C-SO x -C x = 2,3,4 10 μm 0-110 1-210 1.1 nm 1 2 3 4 5 6 7 8 9 0 10 20 30 40 50 Percentage Flakes (%) Number of Layers AFM analysis Chemical Electrochemical Electrochemical Intercalation 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 1x10 4 2x10 4 3x10 4 4x10 4 5x10 4 HI This Method EEG Hydrazine Electrical Conductivity (S m -1 ) Reduction method Thermal Ascorbic Acid
