O-03 AFM IR -OH C=O C=C C-OH O-H C-O m Wavenumber (cm ) nisina-y@cc.okayama-u.ac.jp Height/ nm 1 0-1 (b) 0.8 nm 0.8 nm XPS (C 1s) 0 1 2 3 4 5 Position/ m AFM 50 nm XPS C-O C=O C-C Height/ nm 1 0-1 (b) m 0.8 nm 0.8 nm 0 1 2 3 4 5 Position/ m Height/ nm m 2 1 0.8 nm 0 0 50 100 150 Position/ m
Graphite (1g) Possible Side Reactions Oxidation of graphite is performed in conc. H 2 SO 4. NaNO 3 (1.5 g), H 2 SO 4 (30-100 ml) KMnO 4 (7.5 g), 5 days H 2 O H 2 O 2 aq. 90, 30 min centrifugation oxidation dehydration rearrangement Graphene Oxide cleavage & oxidation cleavage & oxidation How to Optimize the Oxidation Conditions? Trace the intercalation process Optimization of reaction time GIC Graphite (002) 0.335 nm XANES Analysis of Standard Samples Mn +2 (Mn(OAc) 2 ) in situ XRD analysis 1 h 20 min 0 min Trace the oxidation state of Mn Determine the necessary amount of Characteristic of Mn +7 Mn +3 (Mn(OAc) 3 ) Mn +7 (Mn 2 O 7 ) KMnO 4 Mn(VII) in situ XANES analysis Mn(II)
Mn +2 H 2 O 2 treatment Mn +7 Mn +2 H 2 O 2 treatment No Mn +7 30 min 120 min 240 min, then H 2 O Mainly Mn +3 Higher than Mn +3 30 min 120 min, then H 2 O H 2 O 2 treatment Mn 2+ Mn +3 Water addition Leaching of Mn & homogenization No Mn +7 30 min 60 min 120 min, then H 2 O Mn +7 + 3 Mn +3 4 Mn +4 H 2 O 2 addition reduction of Mn +3 or Mn +4 to Mn +2
Mass Production of GO, Based on Mechanistic Study Mn in liquid (%) H 2 O aded Mn 3+ H 2 O Mn 7+ Mn 3+ Time (min) We confirmed water promotes the leaching of Mn from GIC. Oxidation should be controlled before H 2 O addition. Reaction H 2 SO 4 13 L After reaction (ca. 30 L) Continuous centrifugation 12 L >500 g / batch : Graphite H 2 SO 4 KMnO 4 ( equiv) : fluorescent hydrofobic H 2 O H 2 O 2 aq. Purification by centrifugation metallic ionic Graphene Oxide
KMnO 4 XRD mixture Graphite H 2 SO 4 KMnO 4 (3 equiv.) H 2 O H 2 O 2 aq. Purification by centrifugation Highly oxidized GO Graphene Oxide Hydrazine (x L), 90 C, 2 h Reduced Graphene Oxide
2 (degree) 30 w% Absorbed MB on 1 g of GO / mg 350 300 250 200 150 100 50 0 0 10 20 30 40 50 60 Oxygen content / w%
Specific capacitance/ Fg -1 GO 100 80 60 40 20 0 0 10 20 30 40 50 60 GO + alcohol p-tsoh, R-OH, 80, 12 h GO + carboxylic acid p-tsoh, R -CO 2 H, 80, 12 h
Graphene Oxide Pd(OAc) 2 50% aq. EtOH Pd/Graphene Oxide NaBH 4 Ref: ACS Nano, 2010, 4, 547. Nanoscale, 2014, 6, 6501-6505. 6 nm
XRD d = 2.80 nm (C 16 ) 2 DAB larger intercalation d = 1.19 nm C 16 TAB TBAB TMAB Size of intercalator SDS d = 0.87 nm GO d = 0.338 nm Graphite θ Pdppm EL Water flow Nanoscale, 2014, 6, 6501. Appl. Mater. Today, 2015, 1. 1/2 Li3 0.50 Friciton coefficient 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 Purified Water Water-based emulsified liquid Single layer GO dispersion 0.05 0.00 0 10000 20000 30000 40000 50000 60000 Carbon, 2014, 66, 720. Cycles 37
Supercapacitor electrode GO-Paper rgo-paper Light Green Chem., in press Oxidant Large-scale production Sci. Rep. in press Reaction mixture Continuous centrifuge (30 L) (12 L) Press released in Nikkei Newspaper.