Supplementary Figure S1 Images of the catalytically active ba-go. (a) Images of the exfoliated-go suspension (~0.6mg ml -1 ). 1: before base-treating

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1 Supplementary Figure S1 Images of the catalytically active ba-go. (a) Images of the exfoliated-go suspension (~0.6mg ml -1 ). 1: before base-treating (GO), 2: control, sample refluxed in water for 1 hour; 3: after base treating (b-go) and 4: after base-acid treating (ba-go). The base treatment resulted in a color change from yellow-brown to the homogeneous black. As a result, a stable suspension of reduced graphene oxide (r-go) is formed. The control experiment without base treatment shows only a slight color change (from yellow-brown to brown). After removing the base solution by centrifugation, b-go was subsequently treated by HCl, producing insoluble ba-go. (b) Images of the catalytically active ba-go powder. (c) SEM image of ba-go powder, scale bar 1μm. (d) same as (c) but magnified 10 scale bar 100 nm. SEM image of the obtained ba-go shows that the sheets are highly folded.

2 O 2 4, u-h X X X Ar ba-go Ar H u H 2O Ar Br Ph O 2 O 2 OMe O 2 Cl O 2 (a), (b) 5a, 24 h, 78% 5b, 24 h, 75% (a) 5c, 24 h, 89% (a) 5d, 36 h, 74% (a) H H OMe H Cl MeO H 5e,36 h, 76% (c) 5f,36 h, 74% (c) 5g,36 h, 67% (c) 5h,36 h, 68% (c) Supplementary Figure S2 ba-go catalyzed CDC coupling of tetrahydroisoquinoline and carbon nucleophiles. (a) The CDC reaction of 3 (0.25 mmol) and MeO 2 (0.2 ml) was carried out with ba-go (40 mg) in the presence of oxygen (1 atm), affording the products 5a-d. (b) Without ba-go catalyst, 8% of the product 5a is obtained and with GO (40 mg), 58% of 5a is obtained. (c) The CDC reaction of 3 (0.25 mmol) and indoles (0.3 mmol) was carried out with ba-go (50 mg) in the presence of oxygen (1 atm), affording the products 5e-h.

3 Supplementary Figure S3 XPS and analysis on itrogen gas sorption isotherm GO materials before and after base-acid treatment. (a) XPS spectra of GO, and ba-go. X-ray photoelectron spectroscopy (XPS) analysis shows that O/C ratio in the as-synthesized GO decreases remarkably after the base-acid treatment (from 1/2 to 1/4). (b) itrogen gas sorption isotherm for GO and ba-go. Brunauer-Emmett-Teller (BET) analysis indicates that surface area of ba-go (365 m 2 /g) has increased by six times from GO (58 m 2 /g). The sorption properties of the ba-go are remarkably improved as compared to GO.

4 Supplementary Figure S4 Transmission infrared differential spectra of GO annealed at different temperature regimes. (a) 80 C-60 C, (b) 100 C-80 C, (c) 125 C-100 C, (d) 150 C-125 C, (e) 175 C-150 C, (f) 200 C-175 C, and (g) 300 C-200 C. Fourier Transform Infrared (FTIR) Absorption Spectroscopy was performed in situ at different annealing temperatures. This allows us to follow the changes in the functional groups during thermal reduction of GO, and to compare with changes during the base reduction. Oxygen-functionalities mainly remain at o C (no significant change is observed). Since thermal reduction at low temperatures has little effect on the removal of oxygen functionalities, the loss of oxygen-functionalities in GO during the base treatment could be attributed mainly to the effect of the base reduction. In a good agreement with TGA studies, loss of oxygen-functionalities was then observed at elevated temperatures of o C.

5 Supplementary Figure S5 A comparison of as-synthesized GO, thermally reduced GO and ba-go* (RT). Transmission infrared absorbance spectra of (a) GO at room temperature (black), (b) GO after annealing at 200 C (blue), and (c) ba-go* at room temperature (red) referenced to the clean bare Si-SiO 2 substrate, normalized to the maximum intense peak at ~1780 cm -1 for comparison. The recovery of the sp 2 -conjugation is highlighted in yellow. In comparison to GO, hydroxyls (~ cm -1 ) are significantly removed in thermally reduced GO and in ba-go*. An increase in the concentration of sp 2 -conjugation indicates that the base treatment does not only remove oxidative debris but also restores the π-network in GO.

6 Supplementary Figure S6 Transmission infrared differential spectra of b-go annealed at different temperature regimes. (a) 80 C-60 C, (b) 100 C-80 C, (c) 125 C-100 C, (d) 150 C-125 C, (e) 175 C-150 C, (f) 200 C-175 C, and (g) 300 C-200 C. Thermal annealing of b-go indicates that CO 2 (~2340 cm -1 ) is produced at C, which was further removed during thermal treatment of b-go at o C. This CO 2 production supports that the process of base treatment at 120 C can create or enlarge defects by desorption of CO 2 species from defective sites. This key phenomenon was not observed in thermally reduced as-synthesized GO (Supplementary Figure S4).

7 Supplementary Figure S7 AFM topography images of debris and b-go. (a) Aggregated debris isolated from the synthesis process of GO (scale bar, 200 nm). These small debris fragments aggregated via strong hydrogen-bonding and can be seen clearly. Before isolation, they are dispersed as nanosized fragments which coat the surface of GO. (b) based washed GO (b-go) (scale bar, 600 nm). (c) magnified view of b-go (scale bar, 200 nm). (d) AFM Height analysis on the surface of b-go and debris (isolated using ammonia). The AFM topography of the surface shows that base-washed GO is relatively smoother on regions not covered by holes.

8 Supplementary Figure S8 Transmittance spectra (KBr pallet) of GO (red) and Debris (Blue) which was isolated by using ammonia. The IR spectra of the debris also indicate contributions from various oxygen functional groups, which includes contributions from hydroxyls (O-H at ~ cm -1 and ~1380 cm -1, C-OH at ~ ) and carboxyls (COOH at ~ cm -1, ~ cm -1 and ~ cm -1 ). FTIR characterization of the debris is consistent with the previous reports 26,27 and shows that these are highly acidic and oxygenated.

9 Supplementary Figure S9 Chemical stability of ba-go. (a) XPS C1s spectra of GO and ba-go (b). (c) FTIR spectra (KBr pallet) of ba-go powder (blue) and recovered ba-go powder (black). XPS and FTIR studies were carried out on the recovered ba-go (after catalysis reaction) to check if it is totally transformed into graphene and the answer is negative. As shown in the XPS and FTIR spectra, although some groups are reduced after the reaction, we can see clearly that oxygen functionalities still remain in the recovered ba-go. Since epoxy groups in ba-go can be easily modified through ring-opening reactions with amine 12, these new peaks that appear in the recovered ba-go spectra are assigned to υ -H ( cm -1 ), and δ -H (690 cm -1 ).

10 Supplementary Figure S10 Quantification the formation of H 2 O 2 during the reaction. (a) Absorption spectra of the DPD/POD reagent after the reaction with different concentration of H 2 O 2. (b) Standard curve of H 2 O 2 concentration based on its absorbance at 551 nm. (c) The UV-visible absorption spectra of test sample with or without catalyst after adding DPD and POD. (d) The UV-visible absorption spectra of reaction system and 10μM H 2 O 2 solution. Formation of H 2 O 2 during the reaction can be quantified by the spectrophotometric DPD method. This method is based on the POD catalyzed oxidation of DPD by H 2 O 2, which gives the radical cation, DPD +. The radical cation is stabilized by resonance and has two absorption peaks centered at ca. 510 and 551 nm. The absorption at 551 nm is used for the subsequent measurements. The standard curve of absorbance versus the concentration of H 2 O 2 concentration at 551 nm was measured. As shown in this figure, the standard curve is linear when H 2 O 2 concentration ranges from 0-25μM, but above 25 μm it starts to deviate. The concentration of H 2 O 2 in the test sample (400 ml aqueous solution) can be determined by comparing its absorbance at 551 nm with the standard curves. The calculated concentration of H 2 O 2 in the reaction system (10 ml CH 3 C) was 400 μm.

11 Supplementary Figure S11 Electron paramagnetic response spectra of ba-go catalytic reaction system and several control experiments. The EPR signals show the characteristic fingerprint of spin adducts due to superoxide radical ( O 2 ) (DMPO OOH). Control studies show that either in the presence of 2 bubbling (to deoxygenated the solution) or in the absence of GO catalyst, spin signals due to oxygen radical appear to be very low in intensity. Trace amount of O 2 still exists and cannot be completely eliminated because the EPR studies were carried out in the ambient (only with 2 bubbling) and not in glove box due to the configuration of the EPR machine, this is the reason why low signal of spin adduct can be observed. Despite this, it is definitely clear that in the presence of O 2, the signal is stronger compared to when it is absent. In the absence of ba-go catalysts, the signal also decays to a low level. The data supports our mechanism proposed: porous-go help to activate molecular O 2 to produce superoxide radical ( O 2 ) which plays the role as the active oxidant. 1-Pyrenecarboxylic acid, used as a control because it shows very strong catalytic activity similar to ba-go (line b) in this study, also exhibits sharp splitting characteristic of the peroxy radical spin adduct.

12 Supplementary Table S1 ICP-MS (Inductively Coupled Plasma-Mass Spectroscopy) Analysis of GO, Graphite and ba-go. a Element Graphite GO ba-go Mn ppm b ppm < 1.0 ppm Fe ppm ppm ppm Zn ppm ppm ppm Au ppm ppm. D. Ru. D.. D.. D. a 20 mg sample was dissolved by 2 ml of mixture acid (HCl : HO 3 = 3 : 1) and diluted to 10 ml by 5% DI water. b Metal/Sample = 1μg/g.

13 Supplementary Table S2 Oxidative coupling of benzylamine promoted by carbon materials. a 1a H 2 Catalyst, T Solvent 2a Entry Catalyst T ( o C) Solvent Time (h) Yield (%) b, 1 GO 25 CH 3 C GO 50 CH 3 C GO 70 CH 3 C GO 80 CH 3 C GO 80 CH 3 C GO (40 mg) 80 CH 3 C ba-go 80 CH 3 C 8 83 c 8 ba-go 80 CH 3 C CH 3 C 5 <2 10 Impurities/aCl d 80 CH 3 C 5 <2 11 Graphite 80 CH 3 C 5 <2 12 DO e 80 CH 3 C 5 <2 13 Carbon black 80 CH 3 C f ba-go (20 wt. %) 90 (O 2 ) CH 3 C f ba-go (20 wt. %) 90 (Air) CH 3 C f ba-go (20 wt. %) 90 (Ar) CH 3 C g ba-go (5 wt. %) 90 (Air) R-baGO h 80 CH 3 C R*-baGO i 80 CH 3 C b-go 80 CH 3 C bago-phcooh 80 CH 3 C 5 30 a Unless otherwise specified, the reaction was carried out with benzylamine (0.5 mmol), catalyst (25 mg) and CH 3 C (10 ml) in the presence of oxygen (1atm). b GC yield with anisole as the internal standard. c 100 % conversion and trace benzylaldehyde was observed. d Isolated from as-synthesized GO. e ano-diamond oxide obtained by heating nano-diamond (5 nm) at 425 o C. f The reaction was carried out with benzyl amine (1.0 g), ba-go (20 wt. %) and CH 3 C (50 ml) at 90 o C. g The reaction was carried out with benzyl amine (1.0 g), ba-go (5 wt. %) at 90 o C under solvent-free and open-air conditions. h Reducing ba-go with abh 4 at RT. i Treating R-baGO with HCl at RT.

14 Supplementary Table S3 ba-go catalyzed oxidative coupling of various primary amines in a small scale. a X ba-go, O 2 H 2 CH 3 C, 80 o C X X 1 2 Entry Substrates (1) Products (2) Time (h) Yield (%) b 1 X = H (1a) X = H (2a) 5 89 c 2 X= p-cl (1b) X= p-cl (2b) Cl Cl Cl 6 87 H 2 Cl (1c) Cl Cl (2c) 4 X = p-me (1d) X = p-me (2d) X = m-me (1e) X = m-me (2e) X = o-me (1f) X = o-me (2f) S S S 7 87 H 2 (1g) (2g) a The reaction was carried out with amines (0.5 mmol), ba-go (25 mg) and CH 3 C (10 ml) at 80 o C in the presence of oxygen (1atm). b isolated yield. c GC yield with anisole as the internal standard.

15 Supplementary Table S4 Control experiments by using different acids as the catalysts. Acids H 2 CH 3 C, reflux 1a, 1.0 g O 2 (1atm) 2a Entry Acids (20 wt. %) GC-yield 1 ba-go 98% 2 1-Pyrenecarboxylic acid 95% 3 Pyrene <2% 4 Benzoic acid <2% 5 6-Hydroxy-2-naphthoic acid <2% 6 7 D-COOH b TsOH <2% <2% a The reactions were carried out using 20 wt% Acids and 1.0 g benzylamine in CH 3 C (50 ml). b D-COOH (nano-diamond oxide) obtained by heating nano-diamond (5 nm) at 425 o C.

16 Supplementary Methods Gas chromatography (GC) yield standard curve. The response peak area ratios of product -benzylidene benzylaminee and internal standard anisole (A p /A a ) were obtained from Hewlett- Packard Series 6890 GC (Santa Clara, CA, USA) coupled to a Hewlett Packard 5973 Mass Spectrometer detector. The after calibration with anisole as the internal standard. GC-yields were obtained A p /A a Yield

17 In-situ infrared transmission spectroscopy measurements. Prior to the GO sample deposition, a Float Zone Si/SiO 2 (FZ-100), double-side polished substrate was mechanically cleaned by rubbing with a Q-tip soaked with ethyl acetate, ethanol and distilled water. This washing step was then followed by immersing the pre-cleaned substrates in a piranha solution [2 : 1 (v/v) H 2 SO 4 : H 2 O 2 ] at 90 C for 15 minutes. Each of the GO sample (~0.5 μl) was further transferred onto these clean SiO 2 -Si substrates by drop casting with a pasteur pipette followed by an air drying overnight. Thermal annealing of GO film on a SiO 2 coated Si substrate was achieved by a direct resistive heating of the substrate. The annealing chamber (a closed system) was placed in the main compartment of a 2 purged spectrometer (a Thermo Scientific icolet 6700 FT-IR spectrometer with a KBr beam splitter equipped with a deuterated triglycine sulfate (DTGS) detector at a constant nitrogen flow generated by a slight overpressure). The chamber was continuously evacuated ( Torr) during annealing studies in-situ to minimize the environmental effects. Each sample was held by two tantalum clips to permit the resistive heating provided by a 6010A DC power supply (0-200V/0-17A, 1000 W, Hewlett Packard) during experiments. Once the sample was placed into the annealing chamber, the measurements were performed in situ (no sample transfer needed). All temperature readings were monitored by a Eurotherm unit using type K thermocouples spot-welded to a tantalum clip attached to the sample edge. Calibration with a pyrometer indicated that the thermocouple readings were systematically lowered by C in the C range. However, this was a systematic error so that the relative measurements were reproducible. FTIR measurements were performed at room temperature in a continuous vacuum environment with data collected typically 500 scans per loop in the transmission mode. A deuterated triglycine sulfate (DTGS) detector having a mirror optical velocity of cm s -1 was used at a 4 cm -1 resolution. The samples were placed in an annealing chamber and positioned at an infrared incident angle close to the Brewster s angle (70 ). For annealing studies, data collection per loop was performed at 60 C. The annealing time was 5 minutes at each temperature for a stepwise reduction and the total annealing time for the overall experiment per sample

18 was approximately 8 hrs. Each absorbance spectrum was referenced to the clean SiO 2 -Si substrate spectrum collected at 60 C, which was used as a reference room temperature. In addition, differential spectra were referenced to the spectrum collected at 60 C or to the spectrum of the previous annealing temperatures.